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1
Salzmann, Marc, Ribu Cherian, and Hagen Weser. "Robust response of Asian summer monsoon to anthropogenic aerosols in CMIP5 models." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-197058.
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The representation of aerosol processes and the skill in simulating the Asian summer monsoon vary widely across climate models. Yet, for the second half of the twentieth century, the models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) show a robust decrease of average precipitation in the South and Southeast Asian (SSEA) continental region due to the increase of anthropogenic aerosols. When taking into account anthropogenic aerosols as well as greenhouse gases (GHGs), the 15 CMIP5 models considered in this study yield an average June–September precipitation least squares linear trend of −0.20 ± 0.20mm d−1 (50 years)−1, or −2.9%, for all land points in the SSEA region (taken from 75 to
120◦E and 5 to 30◦N) in the years from 1950 to 1999 (multimodel average ± one standard deviation) in spite of an increase in the water vapor path of +0.99 ± 0.65 kg m−2 (50 years)−1 (+2.5%). This negative precipitation trend differs markedly from the positive precipitation trend of +0.29 ± 0.14mm d−1 (50 years)−1, or +4.1%, which is computed for GHG forcing only. Taking into account aerosols both
decreases the water vapor path and slows down the monsoon circulation as suggested by several previous studies. At smaller scales, however, internal variability makes attributing observed precipitation changes to anthropogenic aerosols more difficult. Over Northern Central India (NCI), the spread between precipitation trends from individual model realizations is generally comparable in magnitude to simulated changes due to aerosols, and the model results suggest that the observed drying in NCI might in part be explained by internal variability.
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Salzmann, Marc, Ribu Cherian, and Hagen Weser. "Robust response of Asian summer monsoon to anthropogenic aerosols in CMIP5 models." American Geophysical Union (AGU), 2014. https://ul.qucosa.de/id/qucosa%3A14474.
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The representation of aerosol processes and the skill in simulating the Asian summer monsoon vary widely across climate models. Yet, for the second half of the twentieth century, the models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) show a robust decrease of average precipitation in the South and Southeast Asian (SSEA) continental region due to the increase of anthropogenic aerosols. When taking into account anthropogenic aerosols as well as greenhouse gases (GHGs), the 15 CMIP5 models considered in this study yield an average June–September precipitation least squares linear trend of −0.20 ± 0.20mm d−1 (50 years)−1, or −2.9%, for all land points in the SSEA region (taken from 75 to
120◦E and 5 to 30◦N) in the years from 1950 to 1999 (multimodel average ± one standard deviation) in spite of an increase in the water vapor path of +0.99 ± 0.65 kg m−2 (50 years)−1 (+2.5%). This negative precipitation trend differs markedly from the positive precipitation trend of +0.29 ± 0.14mm d−1 (50 years)−1, or +4.1%, which is computed for GHG forcing only. Taking into account aerosols both
decreases the water vapor path and slows down the monsoon circulation as suggested by several previous studies. At smaller scales, however, internal variability makes attributing observed precipitation changes to anthropogenic aerosols more difficult. Over Northern Central India (NCI), the spread between precipitation trends from individual model realizations is generally comparable in magnitude to simulated changes due to aerosols, and the model results suggest that the observed drying in NCI might in part be explained by internal variability.
3
AlSamra, Jana. "Der Einfluss des Monsuns als bedeutender Klimafaktor auf dem Indischen Subkontinent und seine Beziehung zur geomorphologischen Exposition der Flüsse insbesondere im Bereich des Brahmaputra." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-154638.
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Geprägt wird das Klima auf dem Indischen Subkontinent ganz erheblich durch den Einfluss des Monsuns, der ein Teilelement des gesamten asiatischen Monsunsystems ist. Der Monsun hat als wesentlicher Klimafaktor einen wichtigen Einfluss auf die geomorphologische Entwicklung der Flüsse und Flusstäler des Indischen Subkontinents in Verbindung mit den Überschwemmungen, die durch die Niederschläge des Monsuns verursacht werden.
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Salzmann, Marc, and Ribu Cherian. "On the enhancement of the Indian summer monsoon drying by Pacific multidecadal variability during the latter half of the twentieth century." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-211254.
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The observed summertime drying over Northern Central India (NCI) during the latter half of the twentieth century is not reproduced by the Coupled Model Intercomparison Project Phase 5 (CMIP5) model ensemble average. At the same time, the spread between precipitation trends from individual model realizations is large, indicating that internal variability potentially plays an important role in explaining the observed trend. Here we show that the drying is indeed related to the observed 1950–1999 positive trend of the Pacific Decadal Oscillation (PDO) index and that the relationship is even stronger for a simpler index (S1). Adjusting the CMIP5-simulated precipitation trends to account for the difference between the observed and simulated S1 trend increases the original multimodel average NCI drying trend from −0.09 ± 0.31 mm d−1 (50 years)−1 to −0.54 ± 0.40 mm d−1 (50 years)−1. Thus, our estimate of the 1950–1999 NCI drying associated with Pacific decadal variability is of similar magnitude as our previous CMIP5-based estimate of the drying due to anthropogenic aerosol. The drying (moistening) associated with increasing (decreasing) S1 can partially be attributed to a southeastward (northwestward) shift of the boundary between ascent and descent affecting NCI. This shift of the ascent region strongly affects NCI but not Southeast Asia and south China. The average spread between individual model realizations is only slightly reduced when adjusting for S1 as smaller-scale variability also plays an important role.
5
Salzmann, Marc, and Ribu Cherian. "On the enhancement of the Indian summer monsoon drying by Pacific multidecadal variability during the latter half of the twentieth century." American Geophysical Union, 2015. https://ul.qucosa.de/id/qucosa%3A14975.
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The observed summertime drying over Northern Central India (NCI) during the latter half of the twentieth century is not reproduced by the Coupled Model Intercomparison Project Phase 5 (CMIP5) model ensemble average. At the same time, the spread between precipitation trends from individual model realizations is large, indicating that internal variability potentially plays an important role in explaining the observed trend. Here we show that the drying is indeed related to the observed 1950–1999 positive trend of the Pacific Decadal Oscillation (PDO) index and that the relationship is even stronger for a simpler index (S1). Adjusting the CMIP5-simulated precipitation trends to account for the difference between the observed and simulated S1 trend increases the original multimodel average NCI drying trend from −0.09 ± 0.31 mm d−1 (50 years)−1 to −0.54 ± 0.40 mm d−1 (50 years)−1. Thus, our estimate of the 1950–1999 NCI drying associated with Pacific decadal variability is of similar magnitude as our previous CMIP5-based estimate of the drying due to anthropogenic aerosol. The drying (moistening) associated with increasing (decreasing) S1 can partially be attributed to a southeastward (northwestward) shift of the boundary between ascent and descent affecting NCI. This shift of the ascent region strongly affects NCI but not Southeast Asia and south China. The average spread between individual model realizations is only slightly reduced when adjusting for S1 as smaller-scale variability also plays an important role.
6
Knopf, Brigitte. "On intrinsic uncertainties in earth system modelling." Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2006/1094/.
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Lendt, Ralf. "Reaktionen des oberflächennahen marinen Karbonatsystems im nordwestlichen Arabischen Meer auf den Südwest-Monsun." [S.l. : s.n.], 2000. http://www.sub.uni-hamburg.de/disse/243/Disse.pdf.
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Meyer, Benjamin [Verfasser], Erik [Akademischer Betreuer] Maehle, and Horst [Gutachter] Hellbrück. "Der schwarmfähige Unterwasserroboter Monsun / Benjamin Meyer ; Gutachter: Horst Hellbrück ; Akademischer Betreuer: Erik Maehle." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2020. http://d-nb.info/1207954411/34.
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Wulf, Hendrik. "Seasonal precipitation, river discharge, and sediment flux in the western Himalaya." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5790/.
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Rainfall, snow-, and glacial melt throughout the Himalaya control river discharge, which is vital for maintaining agriculture, drinking water and hydropower generation. However, the spatiotemporal contribution of these discharge components to Himalayan rivers is not well understood, mainly because of the scarcity of ground-based observations. Consequently, there is also little known about the triggers and sources of peak sediment flux events, which account for extensive hydropower reservoir filling and turbine abrasion. We therefore lack basic information on the distribution of water resources and controls of erosion processes.
In this thesis, I employ various methods to assess and quantify general characteristics of and links between precipitation, river discharge, and sediment flux in the Sutlej Valley. First, I analyze daily precipitation data (1998-2007) from 80 weather stations in the western Himalaya, to decipher the distribution of rain- and snowfall. Rainfall magnitude frequency analyses indicate that 40% of the summer rainfall budget is attributed to monsoonal rainstorms, which show higher variability in the orogenic interior than in frontal regions. Combined analysis of rainstorms and sediment flux data of a major Sutlej River tributary indicate that monsoonal rainfall has a first order control on erosion processes in the orogenic interior, despite the dominance of snowfall in this region.
Second, I examine the contribution of rainfall, snow and glacial melt to river discharge in the Sutlej Valley (s55,000 km2), based on a distributed hydrological model, which covers the period 2000-2008. To achieve high spatial and daily resolution despite limited ground-based observations the hydrological model is forced by daily remote sensing data, which I adjusted and calibrated with ground station data. The calibration shows that the Tropical Rainfall Measuring Mission (TRMM) 3B42 rainfall product systematically overestimates rainfall in semi-arid and arid regions, increasing with aridity. The model results indicate that snowmelt-derived discharge (74%) is most important during the pre-monsoon season (April to June) whereas rainfall (56%) and glacial melt (17%) dominate the monsoon season (July-September). Therefore, climate change most likely causes a reduction in river discharge during the pre-monsoon season, which especially affects the orogenic interior.
Third, I investigate the controls on suspended sediment flux in different parts of the Sutlej catchments, based on daily gauging data from the past decade. In conjunction with meteorological data, earthquake records, and rock strength measurements I find that rainstorms are the most frequent trigger of high-discharge events with peaks in suspended sediment concentrations (SSC) that account for the bulk of the suspended sediment flux. The suspended sediment flux increases downstream, mainly due to increases in runoff. Pronounced erosion along the Himalayan Front occurs throughout the monsoon season, whereas efficient erosion of the orogenic interior is confined to single extreme events.
The results of this thesis highlight the importance of snow and glacially derived melt waters in the western Himalaya, where extensive regions receive only limited amounts of monsoonal rainfall. These regions are therefore particularly susceptible to global warming with major implications on the hydrological cycle. However, the sediment discharge data show that infrequent monsoonal rainstorms that pass the orographic barrier of the Higher Himalaya are still the primary trigger of the highest-impact erosion events, despite being subordinate to snow and glacially–derived discharge. These findings may help to predict peak sediment flux events and could underpin the strategic development of preventative measures for hydropower infrastructures.Regen, Schnee- und Gletscherschmelze speisen die Flüsse des Himalajas, die eine große Bedeutung für die Landwirtschaft, Trinkwasserversorgung und Wasserkraftnutzung in Südasien aufweisen. Welchen Anteil die einzelnen Abflusskomponenten am Gesamtabfluss in Raum und Zeit besitzen, ist jedoch kaum quantifiziert, da es in der entlegenen Region an Bodenmessstationen mangelt. Aus diesem Grund ist auch wenig über die Auslöser und Herkunftsgebiete von hohen Sedimentaustragsereignissen bekannt, die im erheblichen Maße dazu beitragen, dass die Kapazität vonWasserkraftreservoiren abnimmt undWasserkraftturbinen abradieren. Daher fehlen bisher grundlegende Informationen zur räumlichen Verteilung von Wasserressourcen und zu den Ursachen von Erosionsprozessen. In dieser Arbeit benutze ich verschiedene Methoden um die Eigenschaften von und die Beziehungen zwischen Niederschlag, Abflussmenge und Sedimentaustrag im Sutlej-Tal zu untersuchen. In einer ersten Studie analysiere ich Tagesniederschläge (1998-2007) von 80 Wetterstationen aus dem westlichen Himalaja, um die räumliche Verteilung von Regen- und Schneeniederschlägen zu charakterisieren. Die weitere Analyse der Magnituden-Häufigkeitsverteilung von Regenfällen zeigt, dass 40% der sommerlichen Niederschläge auf monsunale Starkregenereignisse zurückgehen, die eine höhere Variabilität im Gebirgsinneren aufweisen als an der Gebirgsfront. Die Kombination von Niederschlagsdaten mit Sedimentaustragsdaten für einen der größten Zuflüsse des Sutlejs zeigt, dass monsunaler Niederschlag der primäre Auslöser von Erosionsprozessen im Gebirgsinneren ist, ungeachtet größerer Abflussmengen durch Schnee- und Gletscherschmelze. In einer zweiten Studie untersuche ich den Beitrag von Regen, Schnee- und Gletscherschmelze zur Abflussmenge im Sutlej-Tal (s55.000 km2) mit Hilfe eines hydrologischen Modells für den Jahreszeitraum 2000-2008. Um trotz der begrenzten Bodenmessungen eine hohe räumliche und zeitliche Auflösung zu erzielen, basiert das Modell auf täglichen Fernerkundungsdaten, die ich mit allen verfügbaren Bodenstationsdaten kalibriert und an diese angepasst habe. Die Kalibrierung zeigt, dass das Regenniederschlagsprodukt 3B42 der „Tropical Rainfall Measuring Mission“ (TRMM) den Bodenniederschlag in den semi-ariden bis ariden Gebirgsregionen mit zunehmender Trockenheit systematisch überschätzt. Die Modellierungsergebnisse verdeutlichen, dass die Schneeschmelze den bedeutendsten Beitrag zur Abflussmenge (74 %) zwischen April und Juni aufbringt, während Regen (56%) und Gletscherschmelze (17%) die Monsunsaison (Juli-September) prägen. Daher ist anzunehmen, dass der Klimawandel zu einer Verringerung der Abflussmenge zwischen April und Juni führen wird, was sich besonders auf das Gebirgsinnere auswirkt. In einer dritten Studie untersuche ich mit Hilfe von täglichen Messdaten der letzten Dekade die Ursachen und Eigenschaften des Sedimentaustrags in verschiedenen Bereichen des Sutlej-Einzugsgebietes. Auf der Grundlage von meteorologischen Daten, Erdbebenaufzeichnungen und Gesteinsfestigkeitsmessungen identifiziere ich Starkregenereignisse als häufigste Ursache für extreme Erosionsereignisse, die einen Großteil des gesamten Sedimentaustrags ausmachen. Großräumig betrachtet nimmt der Sedimentaustrag flussabwärts zu, was hauptsächlich auf den Anstieg der Abflussmenge zurückzuführen ist. Zur Monsunzeit treten Erosionsprozesse entlang der Himalajafront besonders häufig auf, während im Gebirgsinneren die Erosion auf einzelne Extremereignisse beschränkt ist. Die Ergebnisse dieser Arbeit untersteichen die Bedeutung von Schnee- und Gletscherschmelze im westlichen Himalaja, in dem große Gebiete nur vereinzelt von monsunalen Niederschlägen erreicht werden. Diese Gebiete sind daher besonders anfällig für den Klimawandel mit weitreichenden Konsequenzen für den Wasserhaushalt in der Region. Die Analyse von Sedimentaustragsdaten zeigt jedoch, dass vereinzelte monsunale Regenstürme, welche die topographische Barriere des Himalaja überqueren, die primäre Ursache von extremen Erosionsereignissen sind, trotz der größeren Abflussmengen von Schnee- und Gletscherschmelze im Gebirgsinneren. Diese Ergebnisse können dazu beitragen, große Erosionsereignisse vorherzusagen und vorbeugende Maßnahmen zum Schutz von Wasserkraftanlagen zu entwickeln.
10
Wolff, Christian. "East African monsoon variability since the last glacial." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5807/.
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The impact of global warming on human water resources is attracting increasing attention. No other region in this world is so strongly affected by changes in water supply than the tropics. Especially in Africa, the availability and access to water is more crucial to existence (basic livelihoods and economic growth) than anywhere else on Earth. In East Africa, rainfall is mainly influenced by the migration of the Inter-Tropical Convergence Zone (ITCZ) and by the El Niño Southern Oscillation (ENSO) with more rain and floods during El Niño and severe droughts during La Niña. The forecasting of East African rainfall in a warming world requires a better understanding of the response of ENSO-driven variability to mean climate.
Unfortunately, existing meteorological data sets are too short or incomplete to establish a precise evaluation of future climate. From Lake Challa near Mount Kilimanjaro, we report records from a laminated lake sediment core spanning the last 25,000 years. Analyzing a monthly cleared sediment trap confirms the annual origin of the laminations and demonstrates that the varve-thicknesses are strongly linked to the duration and strength of the windy season. Given the modern control of seasonal ITCZ location on wind and rain in this region and the inverse relation between the two, thicker varves represent windier and thus drier years. El Niño (La Niña) events are associated with wetter (drier) conditions in east Africa and decreased (increased) surface wind speeds.
Based on this fact, the thickness of the varves can be used as a tool to reconstruct a) annual rainfall b) wind season strength, and c) ENSO variability. Within this thesis, I found evidence for centennialscale changes in ENSO-related rainfall variability during the last three millennia, abrupt changes in variability during the Medieval Climate Anomaly and the Little Ice Age, and an overall reduction in East African rainfall and its variability during the Last Glacial period. Climate model simulations support forward extrapolation from these lake-sediment data, indicating that a future Indian Ocean warming will enhance East Africa’s hydrological cycle and its interannual variability in rainfall. Furthermore, I compared geochemical analyses from the sediment trap samples with a broad range of limnological, meteorological, and geological parameters to characterize the impact of sedimentation processes from the in-situ rocks to the deposited sediments. As a result an excellent calibration for existing μXRF data from Lake Challa over the entire 25,000 year long profile was provided.
The climate development during the last 25,000 years as reconstructed from the Lake Challa sediments is in good agreement with other studies and highlights the complex interactions between long-term orbital forcing, atmosphere, ocean and land surface conditions. My findings help to understand how abrupt climate changes occur and how these changes correlate with climate changes elsewhere on Earth.Änderungen des Klimas in einer sich erwärmenden Erde haben große Auswirkungen auf den globalen und lokalen Wasserhaushalt und rücken anhand starker Extremereignisse immer häufiger in den Fokus der Öffentlichkeit. Besonders die Regionen der Tropen sind von derartigen Einschnitten stark gefährdet. Der jährliche Niederschlag in Ostafrika ist stark mit der saisonalen Wanderung der ITCZ (Innertropischen Konvergenzzone) sowie mit dem El Niño/Southern Oscillation (ENSO) Phänomen verbunden. Extreme Regenfälle und Überschwemmungen während El Niño Jahren stehen Trockenheit und Dürren in La Niña Jahren gegenüber. Prognosen über zukünftige Veränderungen der ostafrikanischen Niederschläge erfordern ein verbessertes Verständnis der ENSO antreibenden Faktoren. Unglücklicherweise sind die vorhandenen meteorologischen Datenreihen nicht lang genug oder besitzen nicht die benötigte Homogenität. Einen hilfreichen Beitrag können jährlich geschichtete Seesedimente des am Fuße des Kilimandscharo gelegenen Lake Challa leisten. Anhand einer monatlich aufgelösten Sedimentfalle konnte ich nachweisen, dass die rund 25.000 Jahre zurückreichenden Sedimente eine jährliche Struktur besitzen sowie die Dicke dieser jährlichen Schichtung (Warve) stark mit der Dauer und Intensität der saisonal windreichen/trockenen Jahreszeit verbunden ist. Dickere Warven repräsentieren windige/trockene Jahre, wohingegen dünnere Warven für windschwache und feuchte Jahre stehen. Stärkere Winde und kaum Niederschläge treten oft im Zusammenhang mit einem La Niña Ereignis in Ostafrika auf, wohingegen während eines El Niño Ereignisses häufig extreme Niederschläge mit wenig Wind zu beobachten sind. Anhand der Vermessung der Warven kann man verschiedene Klimaparameter rekonstruieren: a) den jährlichen Niederschlag b) jährliche Windgeschwindigkeiten und ihre Intensitäten sowie c) ENSO Variabilitäten. Die in meiner Arbeit gewonnenen klimatischen Informationen zeigen starke Änderungen der ENSO Variabilität innerhalb der letzten 3.000 Jahre mit starken Unterschieden während der Kleinen Eiszeit und während der Mittelalterlichen Warmzeit sowie deutlich trockene und windige Bedingungen mit sehr geringen ENSO Aktivitäten im glazialem Zeitraum (18.500 und 21.000 Jahren). Modellberechnungen unterstützen diese Ergebnisse einer Zunahme von Extremereignissen und feuchteren Bedingungen im Zuge einer Erwärmung des Indischen Ozeans. Mittels geochemischer Analysen der Sedimentfallenproben sowie die daraus resultierende Verknüpfung mit limnologischen und meteorologischen Parametern, konnte ich einen entscheidenden Beitrag zur erfolgreichen Interpretation der existierenden 25.000 Jahre langen μXRF Datensätze leisten. Der Anteil an allochthonem und autochthonem Eintrag kann so genau klassifiziert werden. Das dadurch gewonnene Bild der Klimaentwicklung der letzten 25.000 Jahre deckt sich hervorragend mit anderen Studien und ermöglicht Einblicke in das komplexe Zusammenspiel zwischen Ozean-Atmosphäre und Umwelt auf dem afrikanischen Kontinent. Besonders die für die Ostafrikaforschung extrem hohe Auflösung der Daten wird helfen, die abrupten Klimawechsel und Interaktionen besser verstehen zu können.
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Bookhagen, Bodo. "Late quaternary climate changes and landscape evolution in the Northwest Himalaya geomorphologic processes in the Indian summer monsoon domain /." Phd thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974115487.
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Sönnert, Eric. "Afrikas klimat : med fokus på Västafrika." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-218822.
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Då de flesta människor i Västafrika, framför allt de som bor innanför kustzonen, livnär sig på jordbruk så är pålitliga väderprognoser och säsongsförutsägelser ett viktigt hjälpmedel i det dagliga arbetet och planeringen. I den här rapporten har en litteraturstudie gjorts för att öka kunskapen om de komplexa, både lokala och storskaliga, väderfenomen som ger upphov till nederbörd i området. Klimatet i Västafrika, ett område som mestadels täcks av regnskog eller savann, präglas av den västafrikanska monsunen som ger regnperiod under norra halvklotets sommar och torrperiod på vintern. Denna monsun visar på stor årlig variation när det gäller dess inledande faser, och prognoser som kan förutsäga dess början är nödvändigt när en jordbrukare ska planera säsongens verksamhet. Av många bidragande faktorer framgår det tydligt att ytvattentemperaturen i Guineabukten är en av de viktigaste parametrarna för monsunens startskede. Den intertropiska konvergenszonen, ITCZ, betraktas som monsunens nordligaste del och denna konvergenszon gör en plötsligt och relativt snabb förflyttning norrut, i fortsättningen benämnd som språnget, över ca 5 breddgrader, vilket av många ses som starten på regnperioden. En tillfällig tryckgradient som uppstår på grund av en tillfällig men skarp temperaturgradient är den bakomliggande orsaken till detta språng. Den i särklass viktigaste processen som ger upphov till regn i Västafrika är konvektion och även om mycket konvektiv nederbörd faller i samband med monsunen så uppstår det även många lokala och mesoskaliga konvektiva system inom monsunen, framförallt kopplat till ostliga vågor.Since most people in West Africa, particularly those who live away from the shore, work within agriculture, reliable weather forecasts are important in the daily work. In this report, a literature study has been conducted to increase the knowledge about the complex and local weather phenomenon that causes rain. West Africa is dominated by rainforest and savannah, and the climate is characterized by the West African monsoon which gives rise to a wet season in the northern hemisphere summer and a dry season during the winter. The monsoon shows wide annual variability in its initial stages and forecasts that can predict its beginning is necessary to the farmers who have to decide when and what to plant. Out of many contributing factors, the sea surface temperature seems to be one of the main parameters that have an impact on the starting stage of the monsoon. The inter tropical convergence zone, ITCZ, is regarded as the northernmost part of the monsoon and it makes a sudden and relatively quick jump over about 5 degrees latitude, which is widely regarded as the start of the rainy season. A temporary pressure gradient caused by differences in temperature adjacent to the ITCZ is the reason for this jump. The dominant process that causes rainfall in West Africa is convection. Although a lot of convective precipitation falls in connection with the northern part of the monsoon, convective systems can appear inside the monsoon flow, often linked to African easterly waves.
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Ambili, Anoop. "Lake sediments as climate and tectonic archives in the Indian summer monsoon domain." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6479/.
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The Indian summer monsoon (ISM) is one of the largest climate systems on earth and impacts the livelihood of nearly 40% of the world’s population. Despite dedicated efforts, a comprehensive picture of monsoon variability has proved elusive largely due to the absence of long term high resolution records, spatial inhomogeneity of the monsoon precipitation, and the complex forcing mechanisms (solar insolation, internal teleconnections for e.g., El Niño-Southern Oscillation, tropical-midlatitude interactions). My work aims to improve the understanding of monsoon variability through generation of long term high resolution palaeoclimate data from climatically sensitive regions in the ISM and westerlies domain. To achieve this aim I have (i) identified proxies (sedimentological, geochemical, isotopic, and mineralogical) that are sensitive to environmental changes; (ii) used the identified proxies to generate long term palaeoclimate data from two climatically sensitive regions, one in NW Himalayas (transitional westerlies and ISM domain in the Spiti valley and one in the core monsoon zone (Lonar lake) in central India); (iii) undertaken a regional overview to generate “snapshots” of selected time slices; and (iv) interpreted the spatial precipitation anomalies in terms of those caused by modern teleconnections. This approach must be considered only as the first step towards identifying the past teleconnections as the boundary conditions in the past were significantly different from today and would have impacted the precipitation anomalies.
As the Spiti valley is located in the in the active tectonic orogen of Himalayas, it was essential to understand the role of regional tectonics to make valid interpretations of catchment erosion and detrital influx into the lake. My approach of using integrated structural/morphometric and geomorphic signatures provided clear evidence for active tectonics in this area and demonstrated the suitability of these lacustrine sediments as palaleoseismic archives. The investigations on the lacustrine outcrops in Spiti valley also provided information on changes in seasonality of precipitation and occurrence of frequent and intense periods (ca. 6.8-6.1 cal ka BP) of detrital influx indicating extreme hydrological events in the past. Regional comparison for this time slice indicates a possible extended “break-monsoon like” mode for the monsoon that favors enhanced precipitation over the Tibetan plateau, Himalayas and their foothills.
My studies on surface sediments from Lonar lake helped to identify environmentally sensitive proxies which could also be used to interpret palaeodata obtained from a ca. 10m long core raised from the lake in 2008. The core encompasses the entire Holocene and is the first well dated (by 14C) archive from the core monsoon zone of central India. My identification of authigenic evaporite gaylussite crystals within the core sediments provided evidence of exceptionally drier conditions during 4.7-3.9 and 2.0-0.5 cal ka BP. Additionally, isotopic investigations on these crystals provided information on eutrophication, stratification, and carbon cycling processes in the lake.Der Indische Sommer Monsun (ISM) ist eines der bedeutendsten Klimaphänomene auf der Erde und hat großen Einfluss auf die Lebensbedingungen und -grundlagen von nahezu 40% der Weltbevölkerung. Trotz großer Bemühungen ist es bisher nicht gelungen ein genaues und umfassendes Verständnis der Monsun-Variabilität zu gewinnen. Hauptgründe dafür sind das Fehlen von langjährigen und hochaufgelösten Klimazeitreihen, räumlichen Inhomogenitäten in den Niederschlagsverteilungen und die Komplexität der treibenden klimatischen Mechanismen (Sonneneinstrahlung, interne Wechselwirkungen des Klimasystems, wie z.B. zwischen Tropen und mittleren Breiten oder die Auswirkungen der El Niño Oszillation). Die Zielsetzung der hier vorgestellten Arbeit ist ein verbessertes Verständnis der Monsun-Variabilität zu entwickeln, auf Basis von hochaufgelösten und weit reichenden Paläoklimazeitreihen aus klimasensitiven Regionen des ISM und der Westwindzone. Um die Zielsetzung umzusetzen habe ich: (i) Proxys identifiziert (sedimentologische, geochemische, isotopische, und mineralogische), die empfindlich auf Umweltveränderungen reagieren; (ii) die identifizierten Proxys zur Erzeugung von langjährigen Paläoklima-Daten für zwei klimasensible Regionen verwendet, eine im NW des Himalaja (Übergangs-Westwindzone und ISM Gebiet von Spity Valley) und eine in der Kernzone des Monsun (Lonar-See) in Zentralindien; (iii) Übersichts-"Momentaufnahmen" der regionalen klimatischen Bedingungen für ausgewählte Zeitpunkte der Vergangenheit erzeugt; und (iv) räumliche Niederschlagsanomalien in Hinblick auf heutige Wechselbeziehungen im Klimasystem interpretiert. Dieser Ansatz stellt allerdings nur einen ersten Schritt zur Identifizierung von paläoklimatischen Wechselbeziehungen im Monsunsystem dar, da sich die Randbedingungen in der Vergangenheit deutlich von den heutigen unterscheiden und diese einen signifikanten Einfluss auf die Niederschlagsanomalien haben. Da das Spity Valley im tektonisch aktiven Himalaja-Orogen lokalisiert ist, ist es von entscheidender Bedeutung die regionalen tektonischen Prozesse zu verstehen, um Erosionsvorgänge des Einzugsgebiets und die Einfuhr von Detritus in den See korrekt interpretieren zu können. Mein Ansatz der Nutzung kombinierter strukturell/morphometrischer und geomorphologischer Charakteristiken lieferte klare Beweise für aktive Tektonik im untersuchten Gebiet und demonstrierte damit die Eignung dieser lakustrinen Sedimente als paläoseismisches Archiv. Die Untersuchung lakustriner Aufschlüsse in Spity Valley lieferte auch Informationen saisonale Änderung der Niederschlagsverteilung sowie das Auftreten von häufigen und intensiven Perioden (ca. 6,8-6,1 cal ka BP) detritischer Einfuhr, welche auf extreme hydrologische Ereignisse in der Vergangenheit schließen lässt. Ein regionaler Vergleich dieser Periode deutet auf einen möglicherweise erweiterten „break-monsoon-like“ Modus für den Monsun hin, welcher hohe Niederschläge über dem Tibetischen Plateau, dem Himalaja und seinen Gebirgsausläufern begünstigt. Meine Studien an den Oberflächensedimenten des Lonar-Sees haben dazu beigetragen umweltsensitive Proxys zu identifizieren, die auch zur Interpretation von Paläodaten von einem ca. 10 m langen Sedimentkern genutzt wurden, der 2008 erbohrt wurde. Der Kern umfasst das gesamte Holozän und stellt das erste gut 14C-datierte Archiv aus der Kernmonsunzone Zentralindiens dar. Die Identifizierung von authigenen Evaporit-Kristallen (Gaylussite) innerhalb der Sedimente liefert einen Beweis für ungewöhnlich trockene Bedingungen in den Perioden zwischen 4,7-3,9 und 2,0-0,5 cal ka BP. Darüber hinaus lieferten Isotopen-Untersuchungen dieser Kristalle Informationen zur Eutrophierung, Stratifikation und zum Kohlenstoff-Kreislauf des Sees.
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Malik, Nishant. "Extremes in events and dynamics : a nonlinear data analysis perspective on the past and present dynamics of the Indian summer monsoon." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2012/5801/.
Full textAbstract:
To identify extreme changes in the dynamics of the Indian Summer Monsoon (ISM) in the past, I propose a new approach based on the quantification of fluctuations of a nonlinear similarity measure, to identify regimes of distinct dynamical complexity in short time series. I provide an analytical derivation for the relationship of the new measure with the dynamical invariants such as dimension and Lyapunov exponents of the underlying system. A statistical test is also developed to estimate the significance of the identified transitions. Our method is justified by uncovering bifurcation structures in several paradigmatic models, providing more complex transitions compared with traditional Lyapunov exponents. In a real world situation, we apply the method to identify millennial-scale dynamical transitions in Pleistocene proxy records of the south Asian summer monsoon system. We infer that many of these transitions are induced by the external forcing of solar insolation and are also affected by internal forcing on Monsoonal dynamics, i.e., the glaciation cycles of the Northern Hemisphere and the onset of the tropical Walker circulation. Although this new method has general applicability, it is particularly useful in analysing short palaeo-climate records.
Rainfall during the ISM over the Indian subcontinent occurs in form of enormously complex spatiotemporal patterns due to the underlying dynamics of atmospheric circulation and varying topography. I present a detailed analysis of summer monsoon rainfall over the Indian peninsular using Event Synchronization (ES), a measure of nonlinear correlation for point processes such as rainfall. First, using hierarchical clustering I identify principle regions where the dynamics of monsoonal rainfall is more coherent or homogenous. I also provide a method to reconstruct the time delay patterns of rain events. Moreover, further analysis is carried out employing the tools of complex network theory. This study provides valuable insights into the spatial organization, scales, and structure of the 90th and 94th percentile rainfall events during the ISM (June to September). I furthermore analyse the influence of different critical synoptic atmospheric systems and the impact of the steep Himalayan topography on rainfall patterns. The presented method not only helps in visualising the structure of the extremeevent rainfall fields, but also identifies the water vapor pathways and decadal-scale moisture sinks over the region. Furthermore a simple scheme based on complex networks is presented to decipher the spatial intricacies and temporal evolution of monsoonal rainfall patterns over the last six decades. Some supplementary results on the evolution of monsoonal rainfall extremes over the last sixty years are also presented.Um Extremereignisse in der Dynamik des indischen Sommermonsuns (ISM) in der geologischen Vergangenheit zu identifizieren, schlage ich einen neuartigen Ansatz basierend auf der Quantifikation von Fluktuationen in einem nichtlinearen Ähnlichkeitsmaß vor. Dieser reagiert empfindlich auf Zeitabschnitte mit deutlichen Veränderungen in der dynamischen Komplexität kurzer Zeitreihen. Ein mathematischer Zusammenhang zwischen dem neuen Maß und dynamischen Invarianten des zugrundeliegenden Systems wie fraktalen Dimensionen und Lyapunovexponenten wird analytisch hergeleitet. Weiterhin entwickle ich einen statistischen Test zur Schätzung der Signifikanz der so identifizierten dynamischen Übergänge. Die Stärken der Methode werden durch die Aufdeckung von Bifurkationsstrukturen in paradigmatischen Modellsystemen nachgewiesen, wobei im Vergleich zu den traditionellen Lyapunovexponenten eine Identifikation komplexerer dynamischer Übergänge möglich ist. Wir wenden die neu entwickelte Methode zur Analyse realer Messdaten an, um ausgeprägte dynamische Veränderungen auf Zeitskalen von Jahrtausenden in Klimaproxydaten des südasiatischen Sommermonsunsystems während des Pleistozäns aufzuspüren. Dabei zeigt sich, dass viele dieser Übergänge durch den externen Einfluss der veränderlichen Sonneneinstrahlung, sowie durch dem Klimasystem interne Einflussfaktoren auf das Monsunsystem (Eiszeitzyklen der nördlichen Hemisphäre und Einsatz der tropischenWalkerzirkulation) induziert werden. Trotz seiner Anwendbarkeit auf allgemeine Zeitreihen ist der diskutierte Ansatz besonders zur Untersuchung von kurzen Paläoklimazeitreihen geeignet. Die während des ISM über dem indischen Subkontinent fallenden Niederschläge treten, bedingt durch die zugrundeliegende Dynamik der atmosphärischen Zirkulation und topographische Einflüsse, in äußerst komplexen, raumzeitlichen Mustern auf. Ich stelle eine detaillierte Analyse der Sommermonsunniederschläge über der indischen Halbinsel vor, die auf Ereignissynchronisation (ES) beruht, einem Maß für die nichtlineare Korrelation von Punktprozessen wie Niederschlagsereignissen. Mit hierarchischen Clusteringalgorithmen identifiziere ich zunächst Regionen mit besonders kohärenten oder homogenen Monsunniederschlägen. Dabei können auch die Zeitverzögerungsmuster von Regenereignissen rekonstruiert werden. Darüber hinaus führe ich weitere Analysen auf Basis der Theorie komplexer Netzwerke durch. Diese Studien ermöglichen wertvolle Einsichten in räumliche Organisation, Skalen und Strukturen von starken Niederschlagsereignissen oberhalb der 90% und 94% Perzentilen während des ISM (Juni bis September). Weiterhin untersuche ich den Einfluss von verschiedenen, kritischen synoptischen Systemen der Atmosphäre sowie der steilen Topographie des Himalayas auf diese Niederschlagsmuster. Die vorgestellte Methode ist nicht nur geeignet, die Struktur extremer Niederschlagsereignisse zu visualisieren, sondern kann darüber hinaus über der Region atmosphärische Transportwege von Wasserdampf und Feuchtigkeitssenken auf dekadischen Skalen identifizieren.Weiterhin wird ein einfaches, auf komplexen Netzwerken basierendes Verfahren zur Entschlüsselung der räumlichen Feinstruktur und Zeitentwicklung von Monsunniederschlagsextremen während der vergangenen 60 Jahre vorgestellt.
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Zickfeld, Kirsten. "Modeling large-scale singular climate events for integrated assessment." Phd thesis, Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2005/153/.
Full textAbstract:
Erkenntnisse aus paläoklimatologischen Studien, theoretischen Betrachtungen und Modellsimulationen deuten darauf hin, dass anthropogene Emissionen von Treibhausgasen und Aerosolen zu großskaligen, singulären Klimaereignissen führen könnten. Diese bezeichnen stark nichtlineare, abrupte Klimaänderungen, mit regionalen bis hin zu globalen Auswirkungen. Ziel dieser Arbeit ist die Entwicklung von Modellen zweier maßgeblicher Komponenten des Klimasystems, die singuläres Verhalten aufweisen könnten: die atlantische thermohaline Zirkulation (THC) und der indische Monsun. Diese Modelle sind so konzipiert, dass sie den Anforderungen der "Integrated Assessment"-Modellierung genügen, d.h., sie sind realistisch, recheneffizient, transparent und flexibel. Das THC-Modell ist ein einfaches, interhemisphärisches Boxmodell, das anhand von Daten kalibriert wird, die mit einem gekoppelten Klimamodell mittlerer Komplexität erzeugt wurden. Das Modell wird durch die globale Mitteltemperatur angetrieben, die mit Hilfe eines linearen Downscaling-Verfahrens in regionale Wärme- und Süßwasserflüsse übersetzt wird. Die Ergebnisse einer Vielzahl von zeitabhängigen Simulationen zeigen, dass das Modell in der Lage ist, maßgebliche Eigenschaften des Verhaltens komplexer Klimamodelle wiederzugeben, wie die Sensitivität bezüglich des Ausmaßes, der regionalen Verteilung und der Rate der Klimaänderung.
Der indische Monsun wird anhand eines neuartigen eindimensionalen Boxmodells der tropischen Atmosphäre beschrieben. Dieses enthält Parmetrisierungen der Oberflächen- und Strahlungsflüsse, des hydrologischen Kreislaufs und derHydrologie der Landoberfläche. Trotz des hohen Idealisierungsgrades ist das Modell in der Lage, relevante Aspekte der beobachteten Monsundynamik, wie z.B. den Jahresgang des Niederschlags und das Eintritts- sowie Rückzugsdatum des Sommermonsuns, zufrieden stellend zu simulieren. Außerdem erfasst das Modell die Sensitivitätdes Monsuns bezüglich Änderungen der Treibhausgas- und Aerosolkonzentrationen, die aus komplexeren Modellen bekannt sind.
Eine vereinfachte Version des Monsunmodells wird für die Untersuchung des qualitativen Systemverhaltens in Abhängigkeit von Änderungen der Randbedingungen eingesetzt. Das bemerkenswerteste Ergebnis ist das Auftreten einer Sattelknotenbifurkation des Sommermonsuns für kritische Werte der Albedo oder der Sonneneinstrahlung. Darüber hinaus weist das Modell zwei stabile Zustände auf: neben dem niederschlagsreichen Sommermonsun besteht ein Zustand, der sich durch einen schwachen hydrologischen Kreislauf auszeichnet. Das Beachtliche an diesen Ergebnissen ist, dass anthropogene Störungen der plantetaren Albedo, wie Schwefelemissionen und/oder Landnutzungsänderungen, zu einer Destabilisierung des indischen Monsuns führen könnten.
Das THC-Boxmodell findet exemplarische Anwendung in einem "Integrated Assessment" von Klimaschutzstrategien. Basierend auf dem konzeptionellen und methodischen Gerüst des Leitplankenansatzes werden Emissionskorridore (d.h. zulässige Spannen an CO2-Emissionen) berechnet, die das Risiko eines THC-Zusammenbruchs begrenzen sowie sozioökonomische Randbedingungen berücksichtigen. Die Ergebnisse zeigen u.a. eine starke Abhängigkeit der Breite der Emissionskorridore von der Klima- und hydrologischen Sensitivität. Für kleine Werte einer oder beider Sensitivitäten liegt der obere Korridorrand bei weit höheren Emissionswerten als jene, die von plausiblen Emissionsszenarien für das 21. Jahrhundert erreicht werden. Für große Werte der Sensitivitäten hingegen, verlassen schon niedrige Emissionsszenarien den Korridor in den frühen Jahrzehnten des 21. Jahrhunderts. Dies impliziert eine Abkehr von den gegenwärtigen Emissionstrends innherhalb der kommenden Jahrzehnte, wenn das Risko eines THC Zusammenbruchs gering gehalten werden soll.
Anhand einer Vielzahl von Anwendungen - von Sensitivitäts- über Bifurkationsanalysen hin zu integrierter Modellierung - zeigt diese Arbeit den Wert reduzierter Modelle auf. Die Ergebnisse und die daraus zu ziehenden Schlussfolgerungen liefern einen wertvollen Beitrag zu der wissenschaftlichen und politischen Diskussion bezüglich der Folgen des anthropogenen Klimawandels und der langfristigen Klimaschutzziele.
Concerns have been raised that anthropogenic climate change could lead to large-scale singular climate events, i.e., abrupt nonlinear climate changes with repercussions on regional to global scales. One central goal of this thesis is the development of models of two representative components of the climate system that could exhibit singular behavior: the Atlantic thermohaline circulation (THC) and the Indian monsoon. These models are conceived so as to fulfill the main requirements of integrated assessment modeling, i.e., reliability, computational efficiency, transparency and flexibility.
The model of the THC is an interhemispheric four-box model calibrated against data generated with a coupled climate model of intermediate complexity. It is designed to be driven by global mean temperature change which is translated into regional fluxes of heat and freshwater through a linear down-scaling procedure. Results of a large number of transient climate change simulations indicate that the reduced-form THC model is able to emulate key features of the behavior of comprehensive climate models such as the sensitivity of the THC to the amount, regional distribution and rate of change in the heat and freshwater fluxes.
The Indian monsoon is described by a novel one-dimensional box model of the tropical atmosphere. It includes representations of the radiative and surface fluxes, the hydrological cycle and surface hydrology. Despite its high degree of idealization, the model satisfactorily captures relevant aspects of the observed monsoon dynamics, such as the annual course of precipitation and the onset and withdrawal of the summer monsoon. Also, the model exhibits the sensitivity to changes in greenhouse gas and sulfate aerosol concentrations that are known from comprehensive models.
A simplified version of the monsoon model is employed for the identification of changes in the qualitative system behavior against changes in boundary conditions. The most notable result is that under summer conditions a saddle-node bifurcation occurs at critical values of the planetary albedo or insolation. Furthermore, the system exhibits two stable equilibria: besides the wet summer monsoon, a stable state exists which is characterized by a weak hydrological cycle. These results are remarkable insofar, as they indicate that anthropogenic perturbations of the planetary albedo such as sulfur emissions and/or land-use changes could destabilize the Indian summer monsoon.
The reduced-form THC model is employed in an exemplary integrated assessment application. Drawing on the conceptual and methodological framework of the tolerable windows approach, emissions corridors (i.e., admissible ranges of CO2- emissions) are derived that limit the risk of a THC collapse while considering expectations about the socio-economically acceptable pace of emissions reductions. Results indicate, for example, a large dependency of the width of the emissions corridor on climate and hydrological sensitivity: for low values of climate and/or hydrological sensitivity, the corridor boundaries are far from being transgressed by any plausible emissions scenario for the 21st century. In contrast, for high values of both quantities low non-intervention scenarios leave the corridor already in the early decades of the 21st century. This implies that if the risk of a THC collapse is to be kept low, business-as-usual paths would need to be abandoned within the next two decades.
All in all, this thesis highlights the value of reduced-form modeling by presenting a number of applications of this class of models, ranging from sensitivity and bifurcation analysis to integrated assessment. The results achieved and conclusions drawn provide a useful contribution to the scientific and policy debate about the consequences of anthropogenic climate change and the long-term goals of climate protection.
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Anmerkung:
Die Autorin ist Trägerin des von der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam vergebenen Michelson-Preises für die beste Promotion des Jahres 2003/2004.
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Stolbova, Veronika. "Indian Summer Monsoon." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17492.
Full textAbstract:
Das Ziel dieser Arbeit ist es Geheimnisse des Indischen Monsuns aufzudecken-ein groß-skaliges Klimaphänomen,das mehr als 1,7 Milliarden Menschen stark beeinflußt.Folglich ist das Verständnis der Mechanismen des Indischen Monsuns und seine erfolgreiche Prognose nicht nur eine Frage von größtem Interesse,sondern auch eine bedeutende wissenschaftliche Herausforderung.Der erste Teil dieser Arbeit ist den extremen Niederschlagsereignissen über dem Indischen Subkontinent gewidmet.In dieser Arbeit wurde gezeigt,dass eine Synchronizität zwischen extremen Niederschlagsereignissen in den Eastern Ghats und Nord Pakistan Regionen durch das Zusammenspiel zwischen dem indischen Monsun und einem nicht-Monsun-Niederschlagsmuster verursacht wird.Dieses Ergebnis unterstreicht die Bedeutung der Region Nord-Pakistan zur Ableitung der Wechselwirkung zwischen dem indischen Monsun-System und den West-Störungen,und verbessert daher das Verständnis der Kopplung des indischen Monsuns mit den Extratropen.Der zweite Teil der Arbeit befasst sich mit dem Problem der räumlichen und zeitlichen Organisation des abrupten Übergangs auf den indischen Monsun.Hier wird ein neuartiger Mechanismus des räumlich-zeitlichen Übergangs zur Regenperiode vorgeschlagen.Er hat mehrere Vorteile gegenüber bestehenden Erklärungen der Natur des indischen Monsuns:Es beschreibt den abrupten Übergang in einer gewählten Region des indischen Subkontinents sowie die räumliche Ausbreitung und Variabilität des indischen Monsuns beim Einsetzen entlang der Achse des Monsuns.Der dritte Teil dieser Arbeit konzentriert sich auf das Problem der Vorhersagbarkeit des indischen Monsuns.Das vorgeschlagene Verfahren ermöglicht die Vorhersage des Einsetzens und Endens über einen mehr als zwei Wochen bzw.einen Monat früheren Zeitraum im Vergleich zu bisher bekannten Methoden.Schließlich kann die vorgeschlagene Instrumentarium direkt in das bestehende lang-reichweitige Vorhersagesystem für den Monsuns implementiert werden.The aim of this thesis is to uncover some of the mysteries surrounding the Indian Monsoon - a large-scale climatic phenomenon affecting more than 1.7 billion people. Consequently, understanding the mechanisms of the Indian monsoon and its successful forecasting is not only a question of great interest, but also a significant scientific challenge. The first part of this thesis is devoted to extreme rainfall events over the Indian subcontinent. In this thesis, I have shown that a synchronicity between extreme rainfall events in the Eastern Ghats and North Pakistan regions is caused by the interplay between the Indian Monsoon and a non-monsoonal precipitation pattern driven by the Westerlies - Western Disturbances. This result highlights the importance of the North Pakistan region for inferring the interaction between the Indian Monsoon system and Western Disturbances, and, therefore, improves the understanding of the Indian Monsoon coupling with the extratropics. The second part of this dissertation is concerned with the problem of the spatial and temporal organization of the abrupt transition to the Indian monsoon. Here, I have proposed a novel mechanism of a spatio-temporal transition to monsoon. It has several advantages in comparison to existing explanations of the Indian Monsoon nature: it describes the abrupt transition to monsoon in a chosen region of the Indian subcontinent, as well as the spatial propagation and variability of the Indian Monsoon onset along the axis of advance of monsoon. The third part of this thesis focuses on the problem of predictability of the Indian Monsoon. I have developed a novel method that predicts the onset and withdrawal dates more than two weeks and a month earlier than existing methods, respectively. Finally, the proposed scheme can be directly implemented into the existing long-range forecasting system of the monsoon''s timing.
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Kristen, Iris. "Investigations on rainfall variability during the late Quaternary based on geochemical analyses of lake sediments from tropical and subtropical southern Africa." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3254/.
Full textAbstract:
This thesis presents investigations on sediments from two African lakes which have been recording changes in their surrounding environmental and climate conditions since more than 200,000 years. Focus of this work is the time of the last Glacial and the Holocene (the last ~100,000 years before present [in the following 100 kyr BP]). One important precondition for this kind of research is a good understanding of the present ecosystems in and around the lakes and of the sediment formation under modern climate conditions. Both studies therefore include investigations on the modern environment (including organisms, soils, rocks, lake water and sediments).
A 90 m long sediment sequence was investigated from Lake Tswaing (north-eastern South Africa) using geochemical analyses. These investigations document alternating periods of high detrital input and low (especially autochthonous) organic matter content and periods of low detrital input, carbonatic or evaporitic sedimentation and high autochthonous organic matter content. These alternations are interpreted as changes between relatively humid and arid conditions, respectively. Before c. 75 kyr BP, they seem to follow changes in local insolation whereas afterwards they appear to be acyclic and are probably caused by changes in ocean circulation and/or in the mean position of the Inter-Tropical Convergence Zone (ITCZ). Today, these factors have main influence on precipitation in this area where rainfall occurs almost exclusively during austral summer. All modern organisms were analysed for their biomarker and bulk organic and compound-specific stable carbon isotope composition. The same investigations on sediments from the modern lake floor document the mixed input of the investigated individual organisms and reveal additional influences by methanotrophic bacteria. A comparison of modern sediment characteristics with those of sediments covering the time 14 to 2 kyr BP shows changes in the productivity of the lake and the surrounding vegetation which are best explained by changes in hydrology. More humid conditions are indicated for times older than 10 kyr BP and younger than 7.5 kyr BP, whereas arid conditions prevailed in between. These observations agree with the results from sediment composition and indications from other climate archives nearby.
The second lake study deals with Lake Challa, a small, deep crater lake on the foot of Mount Kilimanjaro. In this lake form mm-scale laminated sediments which were analyses with micro-XRF scanning for changes in the element composition. By comparing these results with investigations on thin sections, results from ongoing sediment trap studies, meteorological data, and investigations on the surrounding rocks and soils, I develop a model for seasonal variability in the limnology and sedimentation of Lake Challa. The lake appears to be stratified during the warm rain seasons (October – December and March – May) during which detrital material is delivered to the lake and carbonates precipitate. On the lake floor forms a dark lamina with high contents of Fe and Ti and high Ca/Al and low Mn/Fe ratios. Diatoms bloom during the cool and windy season (June – September) when mixing down to c. 60 m depth provides easily bio-available nutrients. Contemporaneously, Fe and Mn-oxides are precipitating which cause high Mn/Fe ratios in the light diatom-rich laminae of the sediments. Trends in the Mn/Fe ratio of the sediments are interpreted to reflect changes in the intensity or duration of seasonal mixing in Lake Challa. This interpretation is supported by parallel changes in the organic matter and biogenic silica content observed in the 22 m long profile recovered from Lake Challa. This covers the time of the last 25 kyr BP. It documents a transition around 16 kyr BP from relatively well-mixed conditions with high detrital input during glacial times to stronger stratified conditions which are probably related to increasing lake levels in Challa and generally more humid conditions in East Africa. Intensified mixing is recorded for the time of the Younger Dryas and the period between 11.4 and 10.7 kyr BP. For these periods, reduced intensity of the SW monsoon and intensified NE monsoon are reported from archives of the Indian-Asian Monsoon region, arguing for the latter as a probable source for wind mixing in Lake Challa. This connection is probably also responsible for contemporaneous events in the Mn/Fe ratios of the Lake Challa sediments and in other records of northern hemisphere monsoon intensity during the Holocene and underlines the close interaction of global low latitude atmospheric circulation.In dieser Arbeit werden Ergebnisse von Untersuchungen an den Sedimenten zweier afrikanischer Seen vorgestellt, die ein Archiv für Klimaveränderungen über einen Zeitraum von mehr als 200.000 Jahren darstellen. Der Schwerpunkt liegt in dieser Arbeit auf dem letzten Glazial und dem Holozän (ca. 100.000 Jahre vor heute [nachfolgend als 100 kyr BP bezeichnet] bis heute). Grundlegende Voraussetzung für solche Studien ist ein gutes Verständnis der Ökosysteme in und um den See, sowie des gegenwärtigen Sedimentationsgeschehens. Deswegen beinhalten beide Seestudien Untersuchungen der heutigen Organismen, Böden, Gesteine, Wasserchemie und Sedimentablagerungen. Im Tswaing-See im nordöstlichen Südafrika wurden anhand eines 90 m langen Sedimentprofils Studien zur Sedimentzusammensetzung und Untersuchungen der Zusammensetzung und Qualität des organischen Materials durchgeführt. Sie zeigen einen Wechsel zwischen Phasen hohen detritischen Eintrags, während derer v.a. kaum autochthones organisches Material im See erhalten blieb, mit Phasen geringen Eintrags und dafür karbonatischer oder evaporitischer Sedimentation, die hohe Gehalte v.a. autochthonen organischen Materials aufweisen. Diese Phasen werden als relativ feuchte bzw. trockene Perioden interpretiert und folgen bis vor ca. 75 kyr BP Schwankungen der lokalen solaren Einstrahlung. Dieser Einfluss nimmt nach 75 kyr BP ab und azyklische feuchte Phasen werden beobachtet. Mögliche Ursachen sind Veränderungen in der ozeanischen Zirkulation und Verschiebungen in der Lage der Innertropischen Konvergenzzone (ITCZ); beides sind auch heute Haupteinflussfaktoren auf die Niederschläge in der Region. Die heute lebenden Organismen des Tswaing-Kraters wurden mittels Analysen der Biomarkerzusammensetzung und der Kohlenstoffisotopie charakterisiert und ihr Einfluss auf die heutigen Seeablagerungen untersucht. Dabei konnten zusätzlich Indikatoren für die Aktivität methanotropher Bakterien nachgewiesen werden. Der Vergleich heutiger Sedimente mit denen des Zeitraumes 14 bis 2 kyr BP zeigt deutliche Veränderungen sowohl in der Zusammensetzung, als auch in der Kohlenstoffisotopie der Biomarker, die mit Veränderungen in der Hydrologie erklärt werden können. Die gefundenen Hinweise auf feuchtere Bedingungen im Zeitraum älter als 10 kyr BP, für trockenere Verhältnissen zwischen 10 und 7.5 kyr BP und für die nachfolgende Wiederzunahme an Feuchtigkeit werden durch die sedimentologischen Ergebnisse unterstützt. Objekt der zweiten Seestudie ist der Challa-See am Fuß des Kilimanjaro. Hier werden heute im mm-Maßstab laminierte Sedimente gebildet, die mit Mikro-XRF-scanning auf Veränderungen in der Elementzusammensetzung untersucht wurden. Zusammen mit Untersuchungen der Mikrofazies und im Vergleich mit ersten Ergebnissen noch laufender Sedimentfallenstudien, mit meteorologischen Daten und Analysen des Umgebungsgesteins werden die saisonalen Veränderungen in der Temperaturverteilung, der Durchmischungstiefe, dem detritischen Eintrag und der Bioproduktivität des Sees in den Sedimenten nachvollziehbar. Der See ist in den feucht-warmen Perioden von Oktober bis Dezember und von März bis Mai stratifiziert. Während dieser Zeit erfolgt der Eintrag detritischen Materials und Kalziumkarbonat fällt aus; eine dunkle Lage mit hohen Gehalten an Fe und Ti und mit hohen Ca/Al- und niedrigen Mn/Fe-Verhältnissen bildet sich am Boden des Sees. Diatomeen blühen während der kühlen, windigen Periode von Juni bis September, wenn die Durchmischung bis auf etwa 60 m Tiefe Nährstoffe verfügbar macht. Die Ausfällung von Fe- und Mn-oxiden sorgt für hohe Mn/Fe-Verhältnisse; es bildet sich eine helle Lage auf dem Sediment. Trends im Mn/Fe-Verhältnis werden als Signal für Veränderungen in der Intensität oder Dauer der saisonalen Durchmischung interpretiert. Dies wird unterstützt durch parallele Trends im Gehalt an organischem Material und an biogenem Silizium, wie durch Analysen an einem 22 m langen Bohrkern gezeigt werden kann. Nach gut durchmischten und von erhöhtem Eintrag von außen geprägten Verhältnissen während des letzten Glazials erfolgt gegen 16 kyr BP ein Übergang zu stärker stratifizierten Bedingungen. Diese korrespondieren mit einem steigenden Seespiegel und verbreiteten Hinweisen auf feuchte Bedingungen im tropischen Ostafrika. Stärkere Durchmischung herrschte während der Jüngeren Dryas und von 11.4 bis 10.7 kyr BP. Diese Perioden entsprechen Zeiten verringerter Südwest- und vermutlich verstärkter Nordostmonsunintensität im Bereich des Indisch-Asiatischen Monsuns und spiegeln eine global beobachtete südliche Verschiebung der ITCZ wider. Nach einer kurzen stabilen, feuchten Phase im frühen Holozän nimmt die Durchmischung des Sees im Verlauf des Holozän wieder zu. Abrupte Ereignisse während des Holozän scheinen im Challa-See zeitgleich mit Veränderungen der Monsunintensität der Nordhemisphäre aufzutreten und bezeugen die starke klimatische Kopplung der niederen Breiten in globalem Maßstab.
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Maraun, Douglas. "What can we learn from climate data? : Methods for fluctuation, time/scale and phase analysis." Phd thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981698980.
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Mondin, Ludivine. "Homéostasie calcique et survie des cellules musculaires squelettiques déficientes en dystrophine : effets de la modulation de l'activité et de l'expression des récepteurs à l'inositol trisphosphate." Poitiers, 2009. http://theses.edl.univ-poitiers.fr/theses/2009/Mondin-Ludivine/2009-Mondin-Ludivine-These.pdf.
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La dystrophie musculaire de Duchenne (DMD) est une pathologie musculaire sévère caractérisée par l'absence d'une protéine : la dystrophine, protéine sous-membranaire permettant de faire le lien entre la matrice extracellulaire et le cystosquelette. La déficience en dystrophine entraine une dégénérescence musculaire progressive conduisant à la mort du patient. Le lien entre l'absence de dystrophine et la mort des cellules musculaires reste encore mal établi. De nombreuses études ont mis en évidence une dérégulation calcique des cellules musculaires squelettiques déficientes en dystrophine, ainsi qu'une implication des stocks intracellulaires de calcium contenu dans le réticulum sarcoplasmique. De plus, le calcium libéré par les récepteurs à l'IP3 (IP3Rs) semblent être impliqué dans cette dérégulation calcique. Dans cette étude, nous avons confirmé la présence d'une libération calcique globale, après stimulation, supérieure dans les cellules sans dystrophine comparativement aux cellules exprimant la mini-dystrophine. De même, au repos, les libérations calciques localisées spontanées sont plus abondantes dans les cellules déficientes en dystrophine. Ces résultats ont également été observés dans les myotubes provenant de culture primaire de souris mdx (modèle animal de la DMD), comparativement aux souris Bl10 (souris contrôles). Afin d’étudier la régulation de la libération de calcium, des expérimentations de libération calcique artificielle par la méthode de photolyse de calcium encagé ont été menées à différents stades de maturation des cellules musculaires provenant des souris mdx et contrôles. Nous avons également étudié la régulation à court et à long terme du calcium provenant des IP3Rs à l'aide de la cyclosporine A. Cette étude nous a permis de mettre en évidence une possible implication de la voie calcineurine/NFAT. De plus, la régulation pharmacologique de cette voie a révélé une modulation des libérations calciques globales et spontanées, ainsi qu'une diminution de l’expression de l'IP3R1. A ces deux effets, s'ajoute une protection contre la mort cellulaire naturelle des cellules déficientes en dystrophine par la modulation de la voie IP3. Ces résultats suggèrent l'implication des IP3Rs dans la dérégulation calcique des cellules déficientes en dystrophine entraînant la mort prématurée de ces cellules. Il serait maintenant intéressant de comprendre comment la dystrophine intervient dans la modulation de cette voie de libération du calciumIn Duchenne muscular dystrophy, the lack of dystrophin leads to muscle degeneration and progressive weakness. The link between the lack of dystrophin and the cell death is not well established. However, calcium mishandling was observed in dystrophin-deficient muscle cells, involving sarcoplasmic reticulum (SR) calcium stores depending on IP3Rs. Global calcium releases after depolarization and spontaneous calcium events at rest were greater in dystrophin-deficient cells than in mini-dystrophin transfected cells. Theses results were confirmed in primary cultures of myotubes from mdx mouse (animal model of the DMD) comparatively to Bl10 mouse (control mouse). Moreover, the short term and long term IP3 pathway regulation was investigated. This study showed a possible involvement of the calcineurin/NFAT pathway in the IP3R-1 expression. Furthermore, pharmacological regulation of this pathway revealed calcium releases modulation, decrease of IP3R-1 expression and protecting effect against dystrophin-deficient natural cell death. These data suggest the involvement of the IP3Rs calcium mishandling leading to the death of dystrophin-deficient muscle cells. Now, it will be interesting to examine in a deeper way the role of the dystrophin in the modulation of this calcium release pathway
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Pistonetti, Jillian R. "Monsoon Season." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1271362452.
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Cabral, Carlota Vasconcelos Porto. "Quinta do Paço do Monsul - Uma proposta de classificação." Master's thesis, Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa, 2011. http://hdl.handle.net/10362/7308.
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Trabalho de Projecto
Mestrado em Património, área de especialização em
Património HistóricoNo Alto Douro vinhateiro, Património da Humanidade, desenvolverem-se, ao longo da sua história, unidades próprias de exploração e produção agrícola - as Quintas vinhateiras -, espaços indissociáveis do território e paisagem durienses. As Quintas vinhateiras são um importante património imóvel, espelho das vicissitudes da evolução do Douro, constituindo um insubstituível repositório das vivências e do saber fazer duriense. Neste trabalho de projecto, procura demonstrar-se a conveniência da classificação de uma Quinta, propiciando a sua conservação sem adulterações significativas, e garantindo que as gerações vindouras tenham a possibilidade de conhecerem um dos elementos fundamentais da construção da paisagem do Douro vinhateiro. Nesse sentido, procedeu-se ao estudo da quinta do Paço do Monsul, situada na freguesia de Cambes, no concelho de Lamego. Através da pesquisa realizada sobre fundos documentais existentes na propriedade bem como sobre bibliografia disponível, obtiveram-se os dados justificativos para a elaboração de uma proposta de classificação como imóvel de interesse público, atendendo ao facto de este conjunto poder ser considerado como um significativo exemplo de uma quinta duriense dedicada à produção vitivinícola.
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Coupe, Alexandre Robertson. "Grammar of Mongsen Ao /." New York : W. De Gruyter, 2007. http://catalogue.bnf.fr/ark:/12148/cb410951390.
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Kanani, Jesal Harin. "Monsoon caught in Gulmohars." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2562.
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Thesis (M.F.A.) -- University of Maryland, College Park, 2005.Thesis research directed by: Dept. of English. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Monsour, Christopher G. "The effects of literacy intervention in high school biology." Montana State University, 2011. http://etd.lib.montana.edu/etd/2011/monsour/MonsourC0811.pdf.
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In this investigation, issues of reading comprehension in high schools students were explored. Reading comprehension interventions such as metacognitive reading logs were administered with the goal of improving student literacy. Trade books, newspapers, and others types of media were used to differentiate instruction as part of intervention strategies. The results indicate that when students are given the opportunity to read outside of class, their ability to comprehend scientific information increases.
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Vieira, Agudelo Sara C. "Temporal variations of monsoon systems." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37224.
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It has been proposed that the Asian-Australasian monsoon system is influenced by large-scale sea-surface temperature (SST) variability in the three tropical oceans although how this influence is manifested has remained a largely open question. Closure of this issue is important because it is needed to explain trends in monsoon precipitation and circulation that have occurred in the last 30 years. Using an atmospheric general circulation model, we run a series of experiments with different configurations of global SST relating to various epochs occurring during the last century to evaluate their influence on the monsoon. Comparisons of circulation fields show that a colder SST configuration generates a weaker large-scale monsoonal circulation. On the other hand, warmer SST states generate stronger large scale circulations with more vigorous centers of divergence and convergence. Warmer SST configurations are associated with positive anomalies of precipitation in the eastern Bay of Bengal, Eastern Indian Ocean and South East Asia. Cooler SST configurations are associated with negative anomalies of precipitation in the Arabian Sea and Indian peninsula, especially at the beginning of the summer. Since SST gradients determine, to a large degree, the low level flow, they are also going to influence the transport of atmospheric moisture. Comparison of vertically integrated moisture transport fields between the different experiments show that cold SST configuration favors an increased inter-hemispheric flow of moisture but decreases in the westerly moisture flow in to the Bay of Bengal and India. Warm SST configurations, on the other hand, strengthens westerly flow into the eastern Indian Ocean. An increasing availability of moisture in a region of stronger convergence constitutes a favorable environment for the production of monsoonal precipitation.
African easterly waves (AEW) constitute an important component of the African and tropical Atlantic Ocean climate during the boreal summer. An understanding of this component is essential since AEW are closely related with tropical Atlantic storm activity. We adopt an idealized modeling approach using the WRF model initialized with ERA-40 reanalysis data to study the mechanisms that trigger the formation and maintenance of AEW. The model domain includes the African continent, central and eastern Atlantic Ocean and the western Indian Ocean. Experiments are designed to test the relative importance of the thermal effect of the eastern African topography and the influence of the cross-equatorial pressure gradient, induced by the sea surface temperature (SST) on the origins and maintenance of AEW. Topography and SST variation are selectively added and removed. The control experiment shows that the model reproduces many of the mean features observed during the boreal summer. Westward propagating disturbances of 3-8 day period that originate between 30 and 40E at the surface levels and in the mid troposphere are well depicted. In addition, the model provides a reasonable representation of the AEJ.
When all topographic features are removed, there is a weakening of the AEJ over land and ocean, however, longitude-time sections of meridional velocity still exhibit westward propagating disturbances that reach the western African coast at the surface and at the jet level with the same 3-8 day period. Spectral analysis of meridional velocity show that the variability associated with AEWs is reduced over East Africa and West Africa at 850-hPa and is reduced west of 20E along the southern flank of the jet and over northern Africa at the jet level. Maximum amplitude of the disturbances occurs right at the coast. The spatial distribution of barotropic and baroclinic energy conversions explains the reduction in AEWs over land and the intensification of these features at the coast.
When the zonal SST gradient is removed, a weaker AEJ displaces southward and a weaker monsoon flow ensues. Spectral analysis of meridional velocity displays a variance reduction in the 3-8 day band at the 850-hP a level in western and eastern Africa and at the coast. At the 650-hPa level significant changes are not observed at the latitude of the AEJ (15N), however, a decrease in the variance associated with AEW occurs at the southern flank of the jet. A southward displacement of the jet favors a weakening of the baroclinic energy conversions. Barotropic conversions also appear to be weaker when the SST gradient is removed. The present study suggests that orography plays an important role in determining the variability of meridional wind associated with AEW over Eastern Africa at the lower levels. Further, zonal SST gradients over the Atlantic favor intensification of waves when they reach the coast and the maintenance of disturbances across the Ocean. Also, results could suggest that SST gradients support genesis of AEW just off the coast of Africa.
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Candiotto, Bruno Ferres. "Monstr.: entre monstros e aparelhos." Universidade Presbiteriana Mackenzie, 2014. http://tede.mackenzie.br/jspui/handle/tede/1916.
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MONSTR. BETWEEN MONSTERS AND APPARATUS is a theoretical and practical, literary, essayistic and imagery experiment based on applying an artistic operator: monstr. . Through this operator the text of the thesis was constructed proposing a self-questioning of the principles that govern the form of a dissertation in which images and words interacts without hierarchy. What emerges in the dissertation as "monstr." refers to the mode of appointing the creation process, while this process happens considering the strangeness of the act of creation, when creation is actually an interdiction of the creation itself. A radical investment in interdisciplinary dissertation led to the effect of this methodological application. Important authors of the theoretical scenario were used in the process we call "monstrification". Among them fundamentally i quote from Vilém Flusser. He and others served not as authority, but as partners who enter into a dialogue under the proposed methodology. A glossary was built to explain the terms of the text. This glossary aims at bringing the reader closer of the epistemology "monstr." which was used throughout the dissertation extending the theoretical horizons of the reader. The images produced by the "manipulation" of photographs, aims at not to illustrate the text, but to enable a dialogue with it. It suggests a dive in the deep water; a sensory and abysmal depths. All photographs displayed here are nothing more than self-portraits produced by the artistic operator, which exposes them through an admittedly nonlinear aesthetic, emphasizing hybrid characteristics and unusual "plurality" of himself. Actually these photographs have been manipulated and were set to "manipulate" and to be manipulated, causing reflections not only about the "visual" but also about the "sensory" and the myriad of possibilities that this dialectic allows.
MONSTR. ENTRE MONSTROS E APARELHOS é um experimento teórico e prático, literário, ensaístico e imagético baseado na aplicação de um operador artístico: monstr. . Por meio desse operador construiu-se o texto da dissertação proposto como autoquestionamento dos próprios princípios que regem a forma de uma dissertação em que a imagem e a palavra interagem sem hierarquia. Aquilo que na dissertação surge como monstr. refere-se ao modo de nomear o processo de criação, enquanto esse processo se dá tendo em vista a estranheza do próprio ato de criar quando a criação é, na verdade, interdição da própria criação. Um investimento radical na interdisciplinaridade provocou a dissertação como efeito dessa aplicação metodológica. Autores importantes do cenário teórico foram usados dentro do processo que chamamos aqui de monstrificação . Entre eles cito fundamentalmente Vilém Flusser. Ele e outros servem não como autoridade, mas como parceiros que entram em diálogo nos termos da metodologia proposta. Um glossário foi construído para explicitar os termos do texto, esse glossário visa aproximar o leitor da epistemologia monstr. que foi usada ao longo da dissertação ampliando os horizontes teóricos do leitor. As imagens produzidas por manipulação de imagens, fotografias, visam não a ilustração do texto, mas um diálogo com ele. Sugerem um mergulho em águas profundas; profundeza sensorial e abismal. Todas as fotografias aqui expostas nada mais são do que auto-retratos produzidas pelo operador artístico, que as expõe por meio de um estética assumidamente não linear, enfatizando características híbridas e pluralidade incomum, próprias de si mesmo. Tratam-se na verdade de imagens manipuladas, programadas para manipularem por meio delas mesmas, e que permitem serem manipuladas, provocando reflexões não somente acerca do visual , mas também do sensorial e da miríade de possibilidades que essa dialética permite.
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Fosu, Boniface Opoku. "Bay of Bengal: Coupling of Pre-Monsoon Tropical Cyclones With the Monsoon Onset in Myanmar." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3864.
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Myanmar remained largely closed to the world through political instability for several years, when it continued to suffer terribly at the hands of nature that remained largely unknown. Of note is the period between 2008 and 2013, during which the country suffered at least eight major natural calamities that killed more than 141,000 people and affected 3.2 million. The worst of these was Cyclone Nargis in May 2008 that killed more than 130,000. With an estimated $4 billion in damages, Nargis remains the deadliest and most destructive named cyclone ever to have occurred in the North Indian Ocean. Recent studies have shown that, due to increased greenhouse gases and aerosol loading in the atmosphere, more and stronger tropical cyclones (TCs) in the last three decades are tracking eastwards toward the Indochina peninsula. Unfortunately, the Burmese lack the capacity to deal with the impacts of such storms.
Myanmar was left behind as the world made significant technological and industrial advancement; but agriculture, which employs at least 65% of the active labor force, has remained the backbone of the Myanmar economy – an industry that is heavily reliant on monsoon rainfall. The pre-monsoon TC season in the Bay of Bengal (BoB) precedes the onset of the Myanmar monsoon but sometimes the two (i.e.TC formation and the monsoon onset) occur in unison. This work studied the mechanism by which the Madden Julian Oscillation (MJO) modulates the Myanmar monsoon onset and TC activity collectively (i.e. ISO-Onset-TC connection). Avoiding TC destruction at the beginning of the planting season is crucial, so is the monsoon onset date critical for planning. Additional understanding of the aforementioned ISO-Onset-TC connection could provide further insight into predicting the Myanmar monsoon onset and aid in disaster planning for TC impact.
This research is part of a two-year NASA funded project to study extreme climate and weather events.
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Zahid. "The influence of Asian monsoon variability on precipitation patterns over the Maldives." Thesis, University of Canterbury. Department of Geography, 2011. http://hdl.handle.net/10092/5891.
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Asian climate varies on various spatial and temporal scales and has a wide spectrum of climatic characteristics. Climate variability, especially decadal to inter-annual scale rainfall variability across Asia has gained considerable attention of climatologists over the last century due to the fact that rainfall variability is known to have caused considerable damage to southern Asian nations. Until recent, much of the existing literature on southern Asian climate focused on India and it is only recently that studies have focused on countries other than India. Although the Maldives is a nation within southern Asia (lying in the Indian Ocean southwest of India), literature on precipitation patterns over the Maldives and its connection to the Asian monsoon is lacking.
This thesis examines the variability of precipitation over the Maldives in relation to the Asian monsoon, since proper knowledge of the spatial and temporal variations of precipitation is essential for managing the water resources and agricultural sector of the Maldives. Yearly and monthly rainfall across the Maldives indicates that the rainfall varies temporally and spatially. Despite spatial variability of mean annual rainfall (January-December total) showing rainfall increasing from north to south, it was found that on average the northern and southern parts of the Maldives have received less rainfall during the monsoon season (May-November). This suggests that the mean annual rainfall maximum for the Maldives occurs between central and southern parts of the Maldives during the monsoon season. The Maldives monsoon rainfall is characterised by inter-decadal and inter-annual periodicities with a frequency of 12.9 and 2.5-4 years, and intra-seasonal periodicities (10-20 days and 30-60 day) in daily time series of monsoon rainfall for different regions of Asia. The fact that no objective criteria previously existed to identify monsoon onset and withdrawal dates in the Maldives, the criteria developed here for defining the monsoon season objectively for this region indicates that on average the rainy season or monsoon commences between 4 May and 13 May (mean onset dates based on outward longwave radiation (OLR) index and rain and wind criteria, respectively) and terminates in late November (21 and 23 November: mean withdrawal dates based on rain and wind, and OLR index criteria, respectively) for the Maldives. The mean length of the rainy season (LRS) based on the OLR index is 204 days, the mean LRS based on rain and wind is 11 days shorter (193 days). Results also demonstrate that the earliest monsoon onset for the Asian region occurs in the south of the Maldives in April.
Correlation coefficient maps generated between Maldives monsoon rainfall and meteorological parameters suggest that the most significant parameters that influence the interannual variability of the Maldives monsoon rainfall (MMR) are mean sea level pressure, surface air temperature, OLR, sea surface temperature (SST), and the zonal wind and relative humidity at various levels. Temporal consistency checks carried out for these parameters with the MMR led to the elimination of some of these predictors (which have less influence in the variance of MMR). The predictors which explained a significant amount of variance in the MMR were retained, including surface relative humidity during April (SRHAPR), 850 hPa level relative humidity during May (850RHMAY) and 500 hPa relative humidity for May (500RHMAY). These parameters were then used to formulate a regression model (using backward regression) for the prediction of Maldives monsoon rainfall. The predictors included in the model account for a significant part of the variance (76.6%, with a correlation coefficient, CC = 0.9) in MMR, indicating the usefulness of the model for medium-range prediction of MMR before the core monsoon season commences.
Global scale processes such as the El Niño-Southern Oscillation (ENSO) phenomenon influence the weather and climate around the globe, with ENSO considered to be one of the strongest natural phenomena influencing the climate of Asia on inter-annual time-scales. The association between the Maldives monsoon rainfall and ENSO events demonstrates that deficient/excess monsoon rainfall over the Maldives and India region is linked to the strong/moderate El Niño and La Niña events, respectively. During strong/moderate El Niño events, about 71.4% of the time the Maldives/India region experiences deficiencies in monsoon rainfall, while the Maldives/India region experiences excessive monsoon rainfall about 75% of the time during strong/moderate La Niña events. One of the regional scale processes that influence the climate of Asia is Eurasian snow cover. No previous studies have directly examined possible relationships between Eurasian snow and Maldives monsoon rainfall. The possible relationship between Eurasian snow cover (ESC) and the Maldives monsoon rainfall, explored in this research for the first time, appears to be only very weak. The results also demonstrate that the inverse relationship between the ESC and the Indian monsoon has weakened over recent decades. The correlation coefficient (-0.34) between Indian monsoon rainfall and ESC obtained for the 1973-94 period dropped to -0.18 for the 1979-2007 period. The inter-annual variability of the Indian and Australian monsoon rainfall experiences a remarkable biennial oscillation, which has been referred to as the tropospheric biennial oscillation (TBO). It is believed that the land and ocean surface conditions in March-May (MAM) over the Indo-Pacific region play an important role in monsoon transitions. The Maldives monsoon rainfall transition from relatively strong/weak to relatively weak/strong in consecutive years demonstrates a TBO connection (via a biennial tendency in Maldives monsoon rainfall). In relation to the Maldives monsoon rainfall, TBO strong years occur about 47.1% of the time, while weak TBO years occur about 52.9% of the time. Only some of the El Niño and La Niña onset years correspond to strong TBO years, with El Niño onset years (1982, 1987 and 2002) corresponding to weak TBO years, while La Niña onset years (1988 and 2000) corresponding to strong TBO years. Variability (spatial and temporal) in Maldives precipitation associated with global and regional scale processes results in flood and drought events that have downstream impacts, such as on water resources and the agricultural sector of the Maldives. Excess (wet) or deficient rainfall years identified for the period 1992-2008 indicate that the central region is most vulnerable to flooding (5 years with excess rainfall: 27.8% of the time), while the southern region is least vulnerable to both flooding (2 years with excess rainfall: 11.1% of the time) and drought (2 years with deficit rainfall: 11.1% of the time). The northern and central regions show an equal number of years with deficit rainfall (3 years: 16.7% of the time), indicating that they are equally prone to drought events. Furthermore, field survey results demonstrate that about 23, 31 and 37% households (respondents) from the northern, central and southern regions experienced flood events. About 79, 58 and 77% of the farmers from the northern, central and southern areas also experienced floods on their farms. On the other hand, field survey results also suggest that the 49-63% of the households in outer islands of the Maldives and 48-62% of farmers experience shortage of rainwater.
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Robertson, John R. "Evaluating the efficacy of the Staff Sharing Scheme (Gill & Monson 1995)." Thesis, University of East London, 2009. http://roar.uel.ac.uk/3742/.
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This research was small in scale and used a mixed methodological approach to evaluate the Staff Sharing Scheme (SSS) in two primary schools. As such the researcher took a critical realist approach with the purpose of potentially developing the effectiveness of the SSS by understanding the factors that make it effective. The SSS training was delivered and evaluated, using several quantitative techniques for data collection and Thematic Analysis to analyse interview data. The SSS training focused on developing behaviour management techniques using a problem analysis framework and also on building a self-sustaining teacher support group. This study provided further evidence that working with teachers in schools collaboratively to provide teacher support for managing behaviour in their classes, can be constructive and effective. Participants perceived the main benefits to be: an increase in time to reflect on the behaviour problems and a reduction in feelings of isolation by sharing experiences with colleagues. However, a complex picture emerged with teachers not linking the benefits they described when taking part in the SSS training to the need to continue with and establish an ongoing staff support team in their schools. The lack of time in terms of gathering data as well as organising the meeting itself was identified as a reason for not establishing a SSS support group. The findings of a causal attribution measure support interview data suggesting that teachers' existing values, far from being changed by the SSS training, had become more established with teachers more likely to attribute challenging behaviour to within child factors following the SSS training. The existing research and this study indicate that establishing a support group may well need specific long term external support and therefore needs a more longitudinal approach, combined with a larger sample, when researching its effectiveness. The findings are discussed in relation to future research needs and the possible implications for Educational Psychologists in terms of service delivery.
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Rodwell, Mark John. "Dynamics of the Indian summer monsoon." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333428.
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Sconcia, Brett. "Intraseasonal variability of the Indian Monsoon." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646013.
Full textAbstract:
The Indian Monsoon is an extremely important and large-scale meteorological phenomenon that occurs with monotonous regularity every year in the northern hemisphere summer. India and the surrounding regions depend on the monsoon's rains which, although averaged over a season are relatively constant, can vary on timescales of days to weeks with devastating economic and social impact. This study was performed in an effort to gain a little more insight in to the intraseasonal variability of the Indian Monsoon. This was done with the help of an extensive observational study using ECMWF reanalysis data and also some modelling with a simple atmospheric model. In order to interpret results, degrees of simplification will be introduced by compositing and averaging processes that betray the complexities of the monsoon system. However, it will be shown that this allows well-defined atmospheric structures to be obtained for what are known as active and break states of the monsoon. Some observational aspects of the active and break monsoon states will be shown, highlighting the major differences between the two states. This will be followed by a series of modelling experiments with increasing sophistication, although remaining very simple. The results of these will show enough consistency with observations to allow an investigation in to the effects of ENSO on the intraseasonal variability of the Indian monsoon.
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Kuhlmann, Julian, and Johannes Quaas. "How can aerosols affect the Asian summer monsoon?: assessment during three consecutive pre-monsoon seasons from CALIPSOsatellite data." Copernicus Publications, 2010. https://ul.qucosa.de/id/qucosa%3A13831.
Full textAbstract:
The impact of aerosols above and around the Tibetan Plateau on the Asian Summer Monsoon during premonsoon seasons March-April-May 2007, 2008, and 2009 is investigated by means of remote sensing and radiative transfer modelling. Four source regions are found to be responsible for the high aerosol loading around the Tibetan Plateau: the Taklamakan Desert, the Ganges Plains, the Indus Plains, and the Arabian Sea. CALIPSO lidar satellite data, providing vertically resolved images of aerosols, shows aerosol concentrations to be highest in the lower 5 km of
the atmosphere with only little amounts reaching the Tibetan Plateau altitude. Using a radiative transfer model we find that aerosol plumes reduce shortwave radiation throughout the Monsoon region in the seasonal average by between 20 and 30 W/m2. Peak shortwave heating in the lower troposphere reaches 0.2 K/day. In higher layers this shortwave heating is partly balanced by longwave cooling. Although
high-albedo surfaces, such as deserts or the Tibetan Plateau,
increase the shortwave heating by around 10%, the overall effect is strongest close to the aerosol sources. A strong elevated heating which could influence large-scale monsoonal circulations as suggested by previous studies is not found.
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Chabangborn, Akkaneewut. "The Asian monsoon - 50-7 ka BP." Licentiate thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75974.
Full textAbstract:
The Asian monsoon is one of the largest climatic systems on Earth. It covers an area from the Arabian Sea to the South China Sea and from northern Australia to northern China with the world’s highest population density. Moreover, the Asian monsoon transports heat energy and humidity to higher latitudes. In order to better understand the behaviour of the Asian monsoon and its environmental impact, its variability between 50 and 7 ka BP is analysed using paleo-data compilation, data-model comparisons, and lake sediment analysis. The main results presented here are from the compilation of the Asian monsoon variability during the last glacial maximum (LGM) (23 - 19 ka BP) which is presumed to be under persistence cool and dry climatic conditions. The pattern of reconstructed and simulated precipitation agrees well in most of the region. However, the data-model discrepancies show in some areas, which may come from low resolution of the model or the local topographic effect. The reconstructed SSTs are well correlation with simulated SSTs, except in the Arabian Sea. The LGM Asian monsoon changes around 20 – 19 ka BP. The simulated ITCZ varies between 5°N and 15°N in the west and the east of the Asian monsoon region. However, the reconstructed ITCZ is ~5°N in the Arabian Sea, shifts northward in the Bay of Bengal, reaches ~30°N over central of China and migrates southward in the South China Sea. The ITCZ is likely shift northward after 20 ka BP. The climatic change might have been triggered by several factors, e.g., an increased land-sea thermal contrast and a variation of Pacific water inflow.
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Ferranti, Laura. "Tha Asian summer monsoon and its predictability." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339517.
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Privé, Nikki C. 1977. "Axisymmetric theory and the interactive, asymmetric monsoon." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33726.
Full textAbstract:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2005.Includes bibliographical references (p. 201-204).
The applicability of axisymmetric theory of angular momentum conserving circulations to the large-scale steady monsoon is studied in a general circulation model with idealized representations of continental geometry and simple physics. The axisymmetric theory is expanded to explain the location of the monsoon; assuming quasi-equilibrium, the poleward boundary of the monsoon circulation will be collocated with the maximum in subcloud moist entropy, with the monsoon rains occurring slightly equatorward of this maximum. Starting from an axisymmetric aquaplanet framework, the model complexity is incrementally increased to include first a subtropical continent, then eddies and zonal variation in the flow, and finally asymmetry of the large-scale forcing. It is found that the meridional circulation which develops over a zonally symmetric continent is in good agreement with the axisymmetric theory, but a cross-equatorial meridional circulation does not form over a continent of limited longitudinal width, where the flow is highly asymmetric.
(cont.) The equator proves to be a substantial barrier to boundary layer meridional flow; flow into the summer hemisphere from the winter hemisphere tends to occur in the free troposphere rather than in the boundary layer. The monsoon location is found to be strongly correlated with the maximum subcloud moist entropy, both in the modeled cases and in observed monsoons around the globe. The net effect of eddies is a slight weakening of the monsoon due to redistribution of the moist entropy field. Advection is found to strongly shape the overall distribution of subcloud moist entropy, and to limit the range of the monsoon circulation and precipitation.
by Nikki C. Privé.
Sc.D.
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Griffin, Richard Daniel. "North American Monsoon Paleoclimatology From Tree Rings." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301558.
Full textAbstract:
The North American monsoon is central to Southwestern climate and is a research focus in climatology. Of the various monsoon paleoclimate proxies, precisely dated and seasonally resolved tree-ring records offer unique opportunity for contextualizing modern instrumental observations and climate model projections. Focused on latewood, the dark-colored sub-annual component of conifer tree rings that forms in the late growing season, this dissertation research represents a systematic effort to diagnose the tree-growth response to monsoon climate, to develop a replicated network of monsoon-sensitive chronologies, and to characterize monsoon paleoclimate variability in the southwestern United States. A pilot study using latewood measurements from five locations assessed seasonal climate response sensitivity to various chronology development techniques. Results informed a protocol for chronology development, which was used to produce a unique network of 53 monsoon-sensitive latewood chronologies for the southwestern United States. A chronology subset was used to develop the first monsoon precipitation reconstruction for a large and important region of the southwestern United States and northwestern Mexico. This reconstruction revealed monsoon paleodroughts more persistent and extreme than any during the instrumental era and indicated that the southwestern decadal droughts of the last 470 years were characterized not just by cool-season precipitation deficits, but also by persistently dry monsoon conditions. The previously noted tendency for winter and summer precipitation to be out of phase was found to be unstable through time and anomalously strong during the recent instrumental era. The paleoclimatic significance of the new sub-annual chronology network was characterized in terms of chronology signal strength, climate response seasonality, and dominant spatiotemporal structure. With only a few exceptions, the latewood chronologies were found to contain monsoon-specific climate signal that was not available from previously existing records of annual tree-ring width. Principal components analysis revealed that the chronology network captures both temporal variability and spatial structure inherent to monsoon precipitation. As such, proxy data developed in this dissertation are unique are uniquely suited for studying spatiotemporal variability in monsoon paleoclimate. Outcomes from this dissertation are broadly relevant in environmental research and could potentially inform long-term strategies for adaptive management of natural resources.
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Crimmins, Michael. "Arizona and the North American Monsoon System." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/146919.
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Smith, Walter Prestont. "Tropical squall lines of the Arizona monsoon." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184868.
Full textAbstract:
Squall lines possessing nearly all the characteristics of tropical squall lines occasionally develop during the summer monsoon over southern Arizona and northwestern Mexico. Initial thunderstorm formation is over the mountains along the Continental Divide in the late afternoon. Satellite imagery, cloud-to-ground lightning strike data, and surface observations indicate the squall lines move from east to west or northeast to southwest by discrete propagation faster than all the winds below 20 kPa so that most of the anvil clouds lag behind. The synoptic-scale circulation is anomalous with a strong ridge located over the western United States and a deep trough located over the eastern United States. West to northwest winds are found in the boundary layer over southern Arizona and northwest Mexico while a deep layer of east winds are observed above. As a result, most of the environmental wind shear is confined to the lowest 2.5 km above the ground. The low-level wind shear seems to be required for the westward propagation of thunderstorms and the formation of the squall lines. Extremely dry midtropospheric air develops in the easterly flow through some combination of advection and subsidence and also appears to be an important factor in the development of the squall lines. A two-dimensional, nonhydrostatic, numerical model was able to simulate many of the features observed in these squall lines. Solar heating of the elevated terrain in the model caused the initial thunderstorm to develop over the Continental Divide. Continued development of new thunderstorms to the west of the Divide produced a squall line that travelled westward by translation of cells and discrete propagation, wherein new cells would develop 10-25 km ahead of the old ones, at a speed greater than all the winds below 30 kPa. Upward motion produced by westward propagating gravity waves and by the strong low-level convergence found just ahead of the gust front appeared to cause several episodes of discrete propagation. The creation of horizontal potential temperature gradients and the vertical and horizontal advection of preexisting vorticity gradients combined to produce the vorticity field associated with the rear inflow jet that developed beneath the simulated squall line.
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Gochis, David. "Modeled sensitivities of the North American Monsoon." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/289790.
Full textAbstract:
The North American Monsoon System (NAMS) is an important climatological feature of much of southwestern North America because it is responsible for large portions of the annual rainfall in many otherwise arid and semi-arid environments. This dissertation explores issues related to numerical simulation of the North American Monsoon climate. Simulation studies using both an atmospheric general circulation model (AGCM) and a regional climate model (RCM), forced by model analyzed boundary conditions, are presented. The RCM was run for a single season with three different convective parameterization schemes for a single season to assess the sensitivity to convective representation. The main conclusion from these simulations was that substantial differences in both the time-integrated thermodynamic and circulation structures of the simulated July 1999 NAM atmosphere evolve in the simulations when different convective parameterization schemes (CPSs) are used. All simulations reproduced the maximum of precipitation along the western slope of the Sierra Madre Occidental. However, root mean squared errors and model biases in precipitation and surface climate variables were substantial, and showed strong regional dependencies between each of the simulations. There are large differences in the modeled monthly-total surface runoff between simulations. These differences appear to be more closely related to differences in local, precipitation intensity than to time-average or basin-average intensity. It was found that many features of the North American Monsoon were poorly simulated by the AGCM used in its current configuration when using a yearly repeating cycle of sea-surface temperatures. In particular, the model is unable to simulate the regional patterns of monsoon circulation and rainfall. Modeled rainfall over the southwest U.S. and Mexico is much too low, while tropical precipitation is overestimated. Anomalous sea-surface temperature forcing in the Pacific Ocean also induced model responses that resemble observed responses suggesting that sea-surface temperatures may play a modest role in establishing the monsoon circulation and hence in the generation of monsoon rainfall.
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Hinostroza, Zúñiga Ana Ruth. "Factores de riesgo que influyen para el embarazo en adolescentes Centro de Salud Monzón, distrito de Monzón – Huánuco - 2006." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/14108.
Full textAbstract:
Publicación a texto completo no autorizada por el autorDetermina los factores de riesgo que influyen para el embarazo en adolescentes, identifica factores de riesgo socioeconómicos para el embarazo en adolescentes, identifica factores de riesgo psicológicos para el embarazo en adolescentes e identificar factores de riesgo en salud reproductiva para el embarazo en adolescentes. Se utilizó el método descriptivo de corte transversal. El instrumento utilizado fue un formulario tipo cuestionario conformado por preguntas de opción múltiple y opción binaria y como técnica la entrevista. La población estuvo conformada por 40 adolescentes embarazadas, que asistieron al centro de salud para control de embarazo. Existe un porcentaje significativo del 22.5% de las adolescentes embarazadas con factores de riesgo alto, relacionadas a la frecuencia de discusiones en casa llegando al insulto y a la agresión física, agregado a ello están los problemas económicos, baja resiliencia, inicio precoz de las relaciones amorosas e inicio de las relaciones sexuales. Un porcentaje predominante del 57.5% con factores de riesgo bajo relacionadas a la comunicación con los padres, y la no convivencia de los mismos. Y un porcentaje menor del 20% de adolescentes embarazadas no presentan factor de riesgo.
Trabajo académico
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Johansson, Cecilia. "Begränsningar i Monin-Obukhovs similaritetsteori." Thesis, Uppsala universitet, Meteorologiska institutionen, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-392484.
Full textAbstract:
I den här studien analyseras gränsskiktshöjdens betydelse för hastighetsfältet i ytskiktet, med hjälp av Monin-Obukhovs (MO) similaritetsteori. Studien genomfördes för att verifiera tidigare resultat från en Large-Eddy simulering av Khanna och Brasseur (1995) som tyder på att hastighetsfältet inte bara beror på z/L utan även har ett starkt beroende av gränsskiktshöjden. Genom att använda mastmätningar och sonderingar från Marsta studeras hastighetsfältet och speciellt den dimensionslösa vindgradienten (Φm) och de normaliserade hastighetsvarianserna i horisontalled och vertikalled. Det visar sig att båda parametrarna är beroende av gränsskiktshöjden. Resultatet från studien är att MOs similaritetsteori inte gäller för hastighetsfältet vid instabil skiktning vilket är samma resultat som antyddes i Khanna och Brasseurs (1995) studie. Detta tyder på att de storskaliga rörelserna i gränsskiktet påverkar ytskiktet mer än vad som tidigare varit känt.
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Mota, Ruth Cerezo. "Mechanisms controlling precipitation in the North American monsoon." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510937.
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Pajuelo, Santos Víctor Alejandro. "Estudio de la pequeña central hidroeléctrica de Monzón." Bachelor's thesis, Pontificia Universidad Católica del Perú, 2007. http://tesis.pucp.edu.pe/repositorio/handle/123456789/171.
Full textAbstract:
La presente tesis trata sobre el estudio de la Pequeña Central Hidroeléctrica de Monzón, ubicada en la provincia de Huamalíes, departamento de Huanuco.
Empezamos este trabajo viendo los objetivos del proyecto, los cuales eran de dotar de energía eléctrica a la localidad de Monzón.
Para ello hacemos un análisis del mercado eléctrico y vemos las alternativas para cubrir esta demanda de las cuales seleccionamos la Central Hidroeléctrica.
Analizamos las cuencas cercanas a la población y decidimos por la que ofrecía las mejores condiciones para desarrollar el proyecto.
Como en todo proyecto hidroenergético estudiamos primero la disponibilidad de la fuente principal de todo este mecanismo, que es el agua y por ello hacemos los estudios hidrológicos.
A continuación hacemos los estudios geológicos y topográficos del área seleccionada, También hacemos los análisis de los materiales de construcción que hay en las canteras.
Proseguimos con el diseño de las obras y su respectiva justificación. En una central hidroeléctrica se busca que la obra sea bien diseñada, garantizando su buen funcionamiento y estabilidad de sus componentes. Con la demanda encontrada y ubicándonos en la zona del proyecto se ha calculado que se puede construir una PCH de 360 KW de potencia. Hacia ello va nuestro trabajo.
Adicionalmente presentamos los sistemas de transmisión eléctrica a nivel de estructuras típicas y la subestación de salida.
Por último calculamos el presupuesto total del proyecto y realizamos una evaluación económica del mismo para ver su rentabilidad.
Las tablas se encuentran en un archivo excel denominado tablas – tesis y ayudan a esquematizar datos y cálculos en cada capítulo.Tesis
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Kuhlmann, Julian, and Johannes Quaas. "How can aerosols affect the Asian summer monsoon?" Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185964.
Full textAbstract:
The impact of aerosols above and around the Tibetan Plateau on the Asian Summer Monsoon during premonsoon seasons March-April-May 2007, 2008, and 2009 is investigated by means of remote sensing and radiative transfer modelling. Four source regions are found to be responsible for the high aerosol loading around the Tibetan Plateau: the Taklamakan Desert, the Ganges Plains, the Indus Plains, and the Arabian Sea. CALIPSO lidar satellite data, providing vertically resolved images of aerosols, shows aerosol concentrations to be highest in the lower 5 km of
the atmosphere with only little amounts reaching the Tibetan Plateau altitude. Using a radiative transfer model we find that aerosol plumes reduce shortwave radiation throughout the Monsoon region in the seasonal average by between 20 and 30 W/m2. Peak shortwave heating in the lower troposphere reaches 0.2 K/day. In higher layers this shortwave heating is partly balanced by longwave cooling. Although
high-albedo surfaces, such as deserts or the Tibetan Plateau,
increase the shortwave heating by around 10%, the overall effect is strongest close to the aerosol sources. A strong elevated heating which could influence large-scale monsoonal circulations as suggested by previous studies is not found.
45
Garrigues, Véronique. "Adrien de Monluc, comte de Cramail : 1571-1646." Limoges, 2002. http://www.theses.fr/2002LIMO2009.
Full textAbstract:
Adrien de Monluc (1571-1646), porteur d'un patronyme fameux, est connu de ses contemporains sous le titre de comte de Cramail. Gascon et gentilhomme, il guerroie lors de ses jeunes années aux côtés des ligueurs dans le Midi toulousain. En 1605, il est nommé gouverneur du très sensible comté de Foix. Il devient Maréchal de camp sous Louis XIII et prend part aux campagnes militaires menées contre le duc de Rohan en Languedoc. Mais sa participation à la Journée des Dupes et ses intrigues contre Richelieu conduisent à son embastillement le 23 octobre 1635. Il ne recouvre la liberté qu'après la mort du cardinal. L'historiographie, en se fondant sur quelques évènements comme une rencontre avec le philosophe Vanini, a longtemps brossé d'Adrien de Montluc le portrait d'un homme sulfureux et d'un libertin. Or cette étude aussi exhaustive que le permet une documentation mobilisant des sources diplomatiques, littéraires, économiques, notariales révèlent le comte de Cramail sous un jour sensiblement différent. Ce Gascon peut compter sur un réseau de fidèles et de fidélités enracinées dans la Chalosse, développés dans le Languedoc et jusqu'au lointain Angoumois où il possède la principauté de Chabanais. Grand noble, Le comte de Cramail a satisfait aux exigences culturelles des aristocrates de son rang. Protecteurs des belles lettres, il exerça une activité de mécène à la cour et en province, notamment à Toulouse où au début du XVIIe siècle, il fonda l'académie des Philarètes. De son engagement dans les troupes ligueuses à son adhésion à la Milice chrétienne créée par le duc de Nevers, et à ses prises de position en faveur de la croisade contre le Turc, Adrien de Montluc fut sa vie durant un catholique militant qui ne pouvait qu'éprouver de la sympathie pour une Espagne drapée dans la défense de la catholicité. Le portrait un brin convenu et hâtivement composé du libertin se brise. Il laisse place à une personnalité fidèle à sa foi, à son roi, à ses amis poètes, à un prince qui conserve cependant un brin de mystère en l'absence de toute représentation figurée connue.
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Mapes, Brian. "The Australian monsoon and its mesoscale convective systems /." Thesis, Connect to this title online; UW restricted, 1992. http://hdl.handle.net/1773/10068.
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Ma, Hsi-Yen. "Submonthly variability of the South American Monsoon System." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1906574591&sid=1&Fmt=2&clientId=48051&RQT=309&VName=PQD.
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Adang, Thomas Charles. "Structure and dynamics of the Arizona Monsoon Boundary." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184693.
Full textAbstract:
The Arizona Monsoon Boundary is defined as the boundary separating two distinctly different air masses over Mexico, the southwestern United States, and the adjacent Pacific during the summer. The structure and dynamics of this boundary are examined by cross-sectional analysis using three different data sources: (1) a time-height cross section, constructed using radiosonde observations, at the time the boundary initially passed through Tucson in 1984; (2) a composite cross section through the boundary, constructed from the Fleet Numerical Oceanography Center analysis; and (3) a cross section through the boundary using high-resolution fields of temperature, moisture, and geopotential height obtained from the VISSR Atmospheric Sounder (VAS). All three cross sections showed similar structure. In some respects, the Arizona monsoon boundary resembles a mid-latitude front with a distinct and relatively sharp air mass change across the boundary, forced almost entirely by confluence. A direct ageostrophic circulation is produced by this forcing, giving weak ascent on the warm, moist side of the boundary. The gradients and flow associated with the composite boundary are weaker, by a factor of four, than those associated with strong mid-latitude fronts. However, the VAS cross section suggests that, at times, the strength of the boundary approaches that of middle-latitude fronts. The wind shear suggested by the composite boundary ought to be unstable to baroclinic or barotropic processes. Disturbances developing along the boundary have been observed. One example of such a disturbance is examined using GOES imagery, lightning strike data, cloud track winds, and VAS data. Satellite images show the disturbance resembling a mid-latitude occluded cyclone, with an apparent low pressure center over northern Baja California and front-like cloud features extending eastward and southward from the low. Lightning strike data show convective activity occurring along the front-like features. Wind data indicate the presence of a cyclonic circulation south of San Diego along the Baja California coast. Cross sections using VAS data suggest that barotropic and baroclinic energy sources are present and suggest the front-like nature of the cloud feature extending southward from the low pressure center. Additionally, a second disturbance that eventually interacted with the monsoon boundary is briefly examined using satellite imagery.
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Brandt, Richard Raymond. "The North American Monsoon System in Southern Arizona." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195113.
Full textAbstract:
The North American Monsoon System (NAMS) is a dominant factor in climate in the southwestern United States and northwestern Mexico. Despite the influence of the NAMS and the intense research efforts it receives, its predictability, its variability, and the details of its influence on the environment are not well understood. This dissertation is comprised of three papers, which collectively address these three aspects of this complex climate phenomenon through an examination of various data and analyses at multiple spatial and temporal scales, while focusing on impacts in southern Arizona. In the first paper, a modified definition of the NAMS is established to delineate dates for monsoon onset, bursts, breaks, and retreat. The results are applied to an atmospheric compositing study in the second paper and to an applied study of monsoon-wildland fire relationships in the third paper. In the second paper, geopotential height patterns that affect moisture advection are identified. Onset, retreat, and break timing and duration are impacted by shifts in the latitude of the mid-level anticyclone and by lower-level gradients and contour orientation. Analyses in the third paper reveal the some of the complex effects of monsoon onset, variations in break timing and duration, and monsoon retreat on fire occurrence. This research contributes to the current knowledge of the NAMS in general and to the specific regional impacts of the monsoon. The results can (1) improve meteorological forecasts through the recognition of synoptic and sub-synoptic patterns related to the NAMS and (2) help fire managers by expanding the current understanding of the regional controls of wildland fire.
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Breil, Marcus [Verfasser]. "Einfluss der Boden-Vegetation-Atmosphären Wechselwirkungen auf die dekadische Vorhersagbarkeit des Westafrikanischen Monsuns / Marcus Breil." Karlsruhe : KIT Scientific Publishing, 2015. http://www.ksp.kit.edu.
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