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Nannini, Andrea. "La metafisica di Giovanni da Ripa. Le distinctiones 2, 3 e 8 del Commento Sentenziario: edizione del testo e studio dottrinale." Doctoral thesis, Universita degli studi di Salerno, 2014. http://hdl.handle.net/10556/1447.
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2012 - 2013<br>The aim of this Doctoral work is double: (a) to offer the complete edition of three important distinctiones – the second, the third and the eighth – coming from the Sentence Commentary of the Franciscan John of Ripa, who lectured in Paris in the period 1354-1358. These three distinctiones constitute a homogeneous group of questions dealing with the metaphysical issues of the existence and nature of God (immensitas) in its distinction from the nature of created beings (infinitas/finitas), together with the original mechanism called replicatio unitatis divinae which regulates the generation of all created beings [Distinctio 2], the analogy between God and creatures, with the lucid restriction – consciously elaborated after Duns Scotus – of the univocity in the sole created domain [Distinctio 3], and the formal distinction between all the perfectiones originally contained in the divine essence, which do not introduce any form of multiplicity in the Unity of the supersimplex (immensa) divine essence [Distinctio 8]; (b) to offer an elaborated study of the themes present in these distinctiones, not only regarding to Ripa’s thought, but also through the analysis of related philosophical perspectives (Hugolinus of Orvieto, Pierre Ceffons, John of Mirecourt, Francis de Mayronis, Francis of Appignano, Gregory of Rimini and William of Ockham). This duplex intent is reflected in the two volumes which compose this thesis, which aims to discover the thought of a long-time underestimated philosopher. [edited by author]<br>XII n.s.
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León, Federico. "Adjustment of Peruvian family violence to the psychobiogeographic theory of mental health." Pontificia Universidad Católica del Perú, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/101513.
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The psychobiogeographic theory, considering the extent of exposure to ultraviolet radiation, predicts a latitudinal variation of mental health. An analysis of questionnaire responses from 12,604 women in the Peru 2000 Demographic and Family Health Survey was undertaken to test the hypothesis that physical and psychological violence exerted by husbands and parents against women increases with distance from the Equator. The observed effects of latitude were consistent with the theory in the Pacific desert, Sierra steppe, Puna, and Yunga sites, but not in the Amazon eco-region, which could be due to an excess of vitamin D produced north of 5º 50’ S. The theory’s hypotheses concerning urbanization and the Humboldt Current were supported, but the one on altitude was not<br>Considerando el grado de exposición a radiación ultravioleta, la teoría psicobíogeográfica predice una variación latitudinal de la salud mental. Respuestas de 12 604 mujeres en la Encuesta Demográfica y de Salud Familiar Perú 2000 fueron analizadas para determinarsi la violencia física y psicológica ejercida por esposos y padres aumenta con la distancia al ecuador. Los efectos de la latitud fueron consistentes con la teoría en el desierto del Pacífico, la estepa serrana, la puna, y la eco-región Yunga, no así en la Amazonía, tal vez por la producción excesiva de vitamina D al norte de 5º 50’ S. No se halló efectos de la altura, pero los de la urbanización y la corriente de Humboldt fueron los predichos.
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Дядечко, Алла Миколаївна, Алла Николаевна Дядечко, Alla Mykolaivna Diadechko, and A. S. Ponomarenko. "Google latitude." Thesis, Видавництво СумДУ, 2010. http://essuir.sumdu.edu.ua/handle/123456789/18297.
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Oliver, Kevin Ian Colmcille. "Elements of the thermohaline circulation : high latitude buoyancy forcing and low latitude mixing." Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396699.
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León, Federico R. "The latitudinal tilts of wealth and education in Peru: Testing them, explaining them, and reflecting on them." Economía, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/117649.
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Comparisons between countries around the globe reported since 1999 reveal that nations’ wealth consistently increases with distance from the Equator. Is Peru’s territory exempt from this trend? This study used GPS coordinates, questionnaire data, climate files, and census information from the 2000 Peru Demographic and Health Survey, Climate Wizard, and G-Econ data sets toreconcile the contradictory national evidence and understand the role of certain geophysical and social variables. Household assets increase from north to south in the Brack ecological regionswith latitudinal orientation which were studied (Desert, Puna, Yunga, Amazon), especially in rural settings, and as does women’s education, except in the Amazon. Neither temperature nor fourteen other geophysical and social variables account for such effects, though women’s domestic power explains them in the Yunga ecoregion. The findings can be understood through two theoretical perspectives: one, according to the evolutionary theses of Lynn, Rushton, and Kanazawa, suggests the genetic fixation of differential intellectual levels caused by an ancestral adaptation of Peruvian to various conditions of climate and altitude. The other, combining what is known about ultraviolet radiation, vitamin D, and production of sexual hormones with Zajon’sconfluence theory, is defined by fertility rate and the consequent intellectual home environment for the child. Both predict the increment of IQ and educational PISA scores from north to south Peru, but one points toward education and the other to family planning as human development strategies.<br>Resultados de comparaciones reportadas entre países alrededor del globo desde 1999 indican quela riqueza de las naciones crece consistentemente con la distancia a la línea ecuatorial. ¿Está el territorio peruano exento de esta tendencia? Para reconciliar la contradictoria evidencia nacional y entender el rol de ciertos factores geofísicos y sociales, este estudio utilizó coordenadas GPS, datos de cuestionarios, archivos de clima, e información censal existentes en varias bases de datos(Encuesta Demográfica y de Salud Perú 2000, Climate Wizard, G-Econ). Los activos del hogar crecen de norte a sur en las regiones ecológicas de Brack de orientación latitudinal estudiadas (desierto, puna, yunga, Amazonía), especialmente en ámbitos rurales, y la educación de la mujer lo hace en las tres primeras. Ni la temperatura ni otras 14 variables geofísicas y sociales dan cuenta de los efectos, aunque el poder doméstico de la mujer los explica en la ecoregión Yunga. Los resultados pueden entenderse en dos perspectivas teóricas. Una, acorde con las tesis evolucionistas de Lynn, Rushton y Kanazawa, sugiere la fijación genética de niveles intelectuales diferenciales producidos por una adaptación ancestral de los peruanos a distintas condicionesde clima y altura. La otra, combinando lo que se conoce sobre radiación ultravioleta, vitamina D, y producción de hormonas sexuales con la teoría de la confluencia de Zajonc, se define por la tasa de fertilidad y consecuente ambiente intelectual hogareño para el niño. Ambas predicen el incremento del cociente intelectual y los puntajes educativos PISA del norte al sur peruanos, pero de una se desprende la educación y de la otra la planificación familiar como estrategias promotoras de desarrollo humano.
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Jiao, Yu. "High Latitude Ionospheric Scintillation Characterization." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1376909513.
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Fernandez, Marina de Oliveira. "Estrutura latitudinal e temporal de assembleias de cnidários bentônicos em placas de recrutamento em dois portos da costa brasileira." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-01052013-160255/.
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Diferentes escalas espaciais, nas quais diferentes fatores variam, podem ser importantes em estudos da biodiversidade. Estrutura e dinâmica de comunidades marinhas epifaunais variam com a latitude, mas como essa variação muda ao longo do tempo é pouco estudada. Investigamos como a estrutura de assembleias de cnidários bentônicos em portos varia temporalmente em uma latitude tropical e uma subtropical e devido a fatores locais. No Brasil, estudamos recrutamento ao longo de quatro trimestres em duas áreas portuárias (Pecém a 3°32′S e Ilhabela a 23°46′S), e ao longo de dois anos em Ilhabela. Verificamos que (1) a riqueza de espécies segue o gradiente latitudinal, com assembleias de cnidários bentônicos mais ricas no Pecém, o local mais tropical; (2) a composição das assembleias varia muito ao longo do tempo, mas é mais constante na latitude tropical e parece ser uma consequência de maior variação sazonal da temperatura na latitude subtropical; (3) as abundâncias dos membros das assembleias de Ilhabela não são sazonalmente definidas; (4) cada local possui diferentes táxons que são mais importantes na estrutura da assembleia; (5) as assembleias em Ilhabela estão estruturadas conforme o microhabitat, interações bióticas e tempo de submersão. Este estudo destaca a importância da perspectiva temporal no entendimento da dinâmica de comunidades, contribui com o entendimento da importância da escala na determinação de padrões em comunidades marinhas e de como impactos humanos no ambiente dificultam a interpretação e previsão de padrões em comunidades<br>A variety of spatial scales, in which different factors vary, can be important in studies of biodiversity. Structure and dynamics of marine epifaunal communities are known to vary latitudinally, but how that variation changes over time is relatively unstudied. Here we investigate how the structure of fouling assemblages of cnidarians in harbors varies temporally at a tropical and a subtropical latitude and due to local factors. In Brazil, we studied recruitment during four 3 month periods in two harbors (tropical Pecém at 3°32′S and subtropical Ilhabela at 23°46′S) and over two years at Ilhabela. We found that (1) species richness follows a latitudinal gradient with more speciose benthic cnidarian assemblages at tropical Pecém; (2) composition of the assemblages varies widely over time, while being more constant at the tropical latitude and seems to be a consequence of greater seasonal variation in temperature at the subtropical latitude; (3) abundance of members of the assemblages at Ilhabela are not seasonally defined; (4) each site has different taxa that are more important in assemblage structure; (5) assemblages at Ilhabela are structured by microhabitat, biotic interactions and time of submersion. This study highlights the importance of a temporal perspective in understanding community dynamics, contributes to the understanding of the importance of scale in determining patterns of marine communities and how human impacts difficult interpretation and prediction of community patterns
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Robert, Loïc. "Dynamique de variabilité des courants-jets des moyennes latitudes." Electronic Thesis or Diss., Paris 6, 2017. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2017PA066220.pdf.
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Cette étude a pour objectif d'analyser le rôle des ondes de Rossby dans la variabilité des courants-jets troposphériques des moyennes latitudes à l'aide d'un modèle numérique idéalisé. Elle s'intéresse aux mécanismes dynamiques responsables de la persistance des principaux modes de variabilité : celui de déplacement méridien et celui de pulsation d'amplitude. Le premier est souvent le principal mode de variabilité du fait de sa grande persistance causée par une rétroaction positive des ondes de Rossby.Deux nouveaux types de rétroactions négatives ont été mis en évidence à une échelle de temps plus courte que cette rétroaction classique et dont le mécanisme dépend de la nature des ondes impliquées. Ces différents mécanismes sont aussi retrouvés et ainsi validés dans le contexte plus réaliste des données de réanalyse.Une réflexion sur les conséquences du changement climatique est aussi proposée via l'étude de sensibilité menée sur trois paramètres clés du modèle : le gradient méridien de température, conduisant à un mode de déplacement plus persistant dans le futur, la position moyenne du jet, conduisant à un mode moins persistant pour des jets plus proches du pôle, et enfin la friction dans les basses couches de l'atmosphère, aussi étudiée car étant un paramètre plutôt difficile à évaluer et présentant une forte disparité entre les modèles.Cette thèse a donc permis de mettre en évidence deux nouveaux mécanismes de rétroaction des ondes sur les courants-jets et de développer des diagnostics théoriques qui pourront être plus amplement testés et appliqués dans d'autres contextes, particulièrement des réanalyses et des simulations de climat réalistes<br>This study investigate the impact of Rossby waves on the tropospheric midlatitude eddy-driven jets using an idealized numerical model. It focuses on the dynamical mechanisms driving the persistence of the main modes of variability: a shifting mode and a pulsing mode. The shifting mode is often found to be the leading mode of variability due to an enhanced persistence caused by a positive feedback of Rossby waves. Two new kinds of negative feedbacks have been found for a shorter time-scale than the more classical feedback which mechanism depends on wave properties. These new mechanisms have also been found in the more realistic set up of reanalysis. The impact of climate change is also investigated using the sensitivity analysis of the model to three key parameters : the meridional gradient of temperature, which leads to longer lasting phases of the shifting mode in the future, the jet mean position, which leads to less persistent shifting mode for poleward shifted jets, and frictional damping, because it is a parameter difficult to tune and which varies between numerical models. In conclusion, two new feedback mechanisms acting on eddy-driven jets variability have been found and theoretical diagnostics have been developed and could be used to probe more realistic data such as future climate simulations and reanalysis
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Lutman, Emma Rachel. "Investigations into high latitude stratospheric chemistry." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338213.
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Wood, R. G. "Rossby waves in mid-latitude oceans." Thesis, University of Essex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379474.
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Goodman, Jason (Jason Curtis) 1973. "Interannual middle-latitude atmosphere-ocean interactions." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16779.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.<br>Includes bibliographical references (p. 144-151).<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>This thesis discusses the interaction of atmosphere and ocean in midlatitudes on interannual and decadal timescales. We investigate the extent to which mutuallycoupled atmosphere-ocean feedback can explain the observed coupled variability on these timescales, and look for preferred modes of atmospheric response to forcing by sea-surface temperature anomalies. First, we formulate and study a very simple analytical model of the mutual interaction of the middle-latitude atmosphere and ocean. The model is found to support coupled modes in which oceanic baroclinic Rossby waves of decadal period grow through positive coupled feedback between the thermal forcing of the atmosphere induced by associated SST anomalies and the resulting windstress forcing of the ocean. Growth only occurs if the atmospheric response to thermal forcing is equivalent barotropic, with a particular phase relationship with the underlying SST anomalies. The dependence of the growth rate and structure of the modes on the nature of the assumed physics of air-sea interaction is explored, and their possible relation to observed phenomena discussed. We then construct a numerical model with the same physics; this enables us to consider the effects of nontrivial boundary conditions and background flows within the model. We find that the finite fetch of a closed ocean basin reduces growth rate and can lead to decay. However, the coupled mode described above remains the least-damped, and is thus the pattern most easily energized by stochastic forcing. Using a non-uniform atmospheric background flow focuses perturbation energy into particular areas, so that the coupled mode's expression in the atmosphere becomes fixed in space, rather than propagating. This improves the mode's resemblance to observed patterns of variability, such as the North Atlantic Oscillation, which are generally stationary patterns which fluctuate in intensity. The atmospheric component of the coupled mode exists in a balance between Rossby-wave propagation and vorticity advection. This is the same balance as the "neutral vectors" described by Marshall and Molteni (1993). Neutral vectors are the right singular vectors of the linearized atmospheric model's tendency matrix that have the smallest eigenvalues; they are also the patterns that exhibit the largest response to forcing perturbations in the linear model. We explain how the coupled mode arises as the ocean excites atmospheric neutral vectors. Neutral vectors act as pattern-specific amplifiers of ocean SST anomalies. We then proceed to study the neutral vectors of a quasigeostrophic model with realistic mean flow. We find a striking similarity between these patterns and the dominant patterns of variability observed in both the full nonlinear model and in the real world. We provide a mathematical explanation for this connection. Investigation of the "optimal forcing patterns" - the left singular vectors - proves to be less fruitful. The neutral modes have equivalent barotropic vertical structure, but their optimal forcing patterns are baroclinic and seem to be associated with low level heating. But the horizontal patterns of the forcing patterns are not robust, and are sensitive to the form of the inner product used in the SVD analysis. Additionally, applying "optimal" forcing patterns as perturbations to the full nonlinear model does not generate the response suggested by the linear model.<br>by Jason Goodman.<br>Ph.D.
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Lake, Christopher J. "Simulating Response Latitude Effects in Attitude Surveys using IRT." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1394326630.
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Sridharan, S. "Investigation of middle atmospheric winds, waves and tides from low latitudes." Thesis, IIG, 2002. http://localhost:8080/xmlui/handle/123456789/1604.
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A Thesis submitted to the Moanonmaniam Sundaranar University, Tirunelveli, in partial fulfilment of the requirements for the Ph.D. degree under the guidance of Dr. S. Gurubaran, Equatorial Geophysical Research Laboratory, Tirunelveli and Dr. N. Arunachalam, M.S. University, Tirunelveli
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Robinson, Matthew Dean. "The Horse Latitudes." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2371.
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The Horse Latitudes is a collection of stories that documents one infantry squad's time in Baghdad, Iraq. The missions are long stretches of boredom, broken up by flashes of violence. The single sniper shot fired. An IED loosely buried in the roadside, waiting. A schoolyard of kids throwing fist-sized rocks at gun-trucks. The enemy is vast and changing. The downtime is a combination of homesickness, RPGs, and mortar fire. These men suffer through the war, heat, and each other.
These stories look into the fire-fights and their aftermath to get to soldiers' struggles within themselves: how to fight a faceless enemy, what it means to serve, how one soldiers, what makes a man, what makes a good man, what will it mean to die here, and what does it mean not to. This collection dismisses what we think we know about war -- violence, camaraderie, masculinity, enemy, victory -- in order to tell a harder, truer story.
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Medina, Valles María del Socorro. "Orographic enhancement of mid-latitude cyclone precipitation /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/10028.
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Townsend, William A. "Inertia-gravity waves beyond the inertial latitude." Thesis, Keele University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534319.
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Boutle, Ian. "Boundary-Layer Processes in Mid-latitude Cyclones." Thesis, University of Reading, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520124.
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Smith, Rasler W. "Low latitude ionospheric effects on radiowave propagation." Thesis, Monterey, California. Naval Postgraduate School, 1998. http://hdl.handle.net/10945/8638.
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This dissertation provides experimental observations and analyses that associate low-latitude transionospheric signal scintillation with transequatorial VHF radio propagation and errors in transionospheric geopositioning. The experiment observed equatorial-region ionospheric total electron content (TEC) derived from Global Positioning System (GPS) signals using receivers on Oahu, Hawaii, Christmas Island, and Rarotonga, Cook Islands. The experiment simultaneously measured VHF transequatorial propagation of VHF television signals from Hawaii to Rarotonga Analysis shows that a moving second moment of vertical-equivalent TEC strongly correlates to each VHF transequatorial radio propagation event From experimental observation analysis, the author develops models for prediction of TEP and nine-space distribution of low-latitude transionospheric scintillation. The author also develops equations that show the potential errors in nine, frequency, and angle used in geopositioning solutions. These three parameters are potentially correctable using these techniques
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Burrage, Mark. "Radar studies of high latitude convection flows." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/35849.
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Studies of the electrodynamics of the high latitude ionosphere contribute to the understanding of the coupling between the solar wind, magnetosphere and upper atmosphere. This thesis describes an experimental investigation of high latitude E-region convection flows carried out with the Sweden And Britain auroral Radar Experiment (SABRE). The ionospheric observations have been related to satellite measurements of the interplanetary medium and hence interpreted in terms of models of solar wind-magnetosphere-ionosphere coupling processes. A close relationship has been established between various solar wind parameters and the daily mean SABRE backscatter intensity, a quantity which is rarely employed in geophysical studies. Empirical IMF-dependent models of the convection flows observed by SABRE are developed and statistical studies of the occurrence time of the Harang discontinuity are presented. High spatial resolution, two dimensional maps of the ionospheric projection of the dayside merging region, for both polarities of the azimuthal component of the IMF, are obtained for the first time. Two examples of strong nightside convection flows observed throughout the SABRE latitude range indicate that the convection flows may penetrate at least as far south as 61.5° N, geomagnetic latitude, during strongly northward IMF. The study indicates that, in the long term, the structure of the solar wind can be deduced from the mean backscatter intensity measured by a SABRE radar. In addition, the azimuthal component of the IMF exherts a crucial influence on the convection flows observed by SABRE in the cusp region. This effect is not confined to the noon sector but is also apparent in the vicinity of the Harang discontinuity. In general, the convection pattern exhibits a dependence on the north-south component of the IMF consistent with established reconnection mechanisms. However, there is evidence that existing models are insufficient to explain the anomalous convection flows observed under conditions of strongly northward IMF.
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Straathof, Gijsbert Bastiaan. "Neoproterozoic low latitude glaciations : an African perspective." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/9607.
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The Neoproterozoic is one of the most enigmatic periods in Earth history. In the juxtaposition of glacial and tropical deposits the sedimentary record provides evidence for extreme climate change. Various models have tried to explain these apparent contradictions. One of the most popular models is the Snowball Earth Hypothesis which envisages periods of global glaciations. All climatic models are dependent on palaeogeography which as yet remains poorly constrained for the Neoproterozoic. This thesis presents a multidisciplinary study of two Neoproterozoic sedimentary basins on the Congo and West Africa cratons including radiometric dating of glacial deposits themselves. In the West Congo Belt, western Congo Craton, a new U-Pb baddeleyite age for the Lower Diamictite provides the first high quality direct age for the older of two glacial intervals. This age is significantly different from previously dated glaciogenic deposits on the Congo Craton. This result strongly suggests that the mid-Cryogenian was a period during which several local glaciations occurred, none of which were global. While the palaeomagnetic results from carbonates around the younger glacial interval are probably remagnetised, detrital zircon and chemostratigraphic results allow correlation with numerous late-Cryogenian glaciogenic deposits worldwide and a Snowball Earth scenario is favoured here. In the Adrar Sub-Basin of the vast Taoudéni Basin, West Africa, the terrigenous Jbeliat glacial horizon has been studied in great detail. Detrital zircon geochronology reveals large changes in provenance through this glacial unit with implications for sedimentological approaches and techniques for provenance characterisations based on one sample alone. Together with recently published U-Pb data these results constrain the age of the Jbeliat Group to a narrow window providing vital geochronological information for this younger glacial event. Combining provenance geochemistry, chemostratigraphy and U-Pb dating has greatly improved our understanding of two of the largest Neoproterozoic sedimentary basins. The dominance of Mesoproterozoic detrital material, for which no source has been reported near either of the field areas, has consequences for the proximity of other cratons at the time of deposition, prior to the final amalgamation of Gondwana.
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Kehrwald, Natalie Marie. "Low-latitude Ice Cores and Freshwater Availability." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1245169721.
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Swick, William A. "High latitude coupled sea-ice-air thermodynamics." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FSwick.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, Sept. 2004.<br>Thesis advisor(s): Roland W. Garwood. Includes bibliographical references (p. 71-73). Also available online.
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Ashton, Louise. "Moths and Mountains: Diversity, Altitude and Latitude." Thesis, Griffith University, 2013. http://hdl.handle.net/10072/365540.
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Moth assemblages have been widely used to examine patterns of beta-diversity in forest ecosystems. This thesis aims to expand and test the generality of results obtained as part of the IBISCA-Queensland Project (Investigating Biodiversity of Soil and Canopy Arthropods-Qld) which examined patterns of diversity in a large sub-set of night-flying moths along an altitudinal gradient in subtropical rainforest. The permanent IBISCA-Qld transect, located in Lamington National Park (NP), in south-east Queensland, Australia, spans altitudes from 300 to 1100 meters above sea level (m a.s.l.) within continuous rainforest. Along this transect, moth assemblages showed strong altitudinal stratification. A number of species were restricted to the Nothofagus moorei dominated cloud forest around 1100m a.s.l., and may be the most threatened by climatic change. The IBISCA-Qld Project produced a set of moth species that could be included within a predictor set of taxa that may be useful for future monitoring of the impact of global warming on forest biodiversity. The IBISCA-Qld study was predicated on the idea that a range of adjacent climates along a single altitudinal gradient can be taken as a surrogate for larger scale climatic changes which occur along latitudinal gradients. This thesis expands on the IBISCA-Qld Project by establishing a latitudinal network of analogous altitudinal transects, in Australia and south-west China (tropical, subtropical and sub-alpine temperate forests), allowing inter-continental comparisons on the generality of altitudinal patterns of diversity.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Griffith School of Environment<br>Science, Environment, Engineering and Technology<br>Full Text
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Vichare, Geeta. "Theoretical modelling of low latitude current system." Thesis, Indian Institute of Geomagnetism, Mumbai, 2001. http://localhost:8080/xmlui/handle/123456789/210.
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Adsten, Monika. "Solar thermal collectors at high latitudes design and performance of non-tracking concentrators /." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/fulltext/91-554-5274-4.pdf.
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Linkimer, Abarca Lepolt. "Lithospheric Structure of the Pampean Flat Slab (Latitude 30-33S) and Northern Costa Rica (Latitude 9-11N) Subduction Zones." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202730.
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The Pampean flat slab subduction in west-central Argentina (latitude 30-33S) and the steeply dipping Northern Costa Rica subduction zone (latitude 9-11N) show significant along-trench variations in both the subducting and overriding plates. This dissertation contains the results of three seismological studies using broadband instruments conducted in these subduction zones, with the aim of understanding the structure of the lithosphere and the correlation between the variability observed in the downgoing and the overriding plates. In the Costa Rica region, by analyzing teleseismic receiver functions we investigate the variability in the hydration state of the subducting Cocos Plate and the nature of three distinct crustal terranes within the overriding Caribbean Plate: the Nicoya and Chorotega terranes that display an oceanic character, and the Mesquito Terrane, which is more compatible with continental crust.In the Pampean region of Argentina, we apply a regional-scale double-difference tomography algorithm to earthquake data recorded by the SIEMBRA (2007-2009) and ESP (2008-2010) broadband seismic networks to obtain high-resolution images of the South America lithosphere. We find that most of the upper mantle has seismic properties consistent with a depleted lherzolite or harzburgite, with two anomalous regions above the flat slab: a higher Vp/Vs ratio anomaly consistent with up to 10% hydration of mantle peridotite and a localized lower Vp/Vs ratio anomaly consistent with orthopyroxene enrichment. In addition, we study the geometry and brittle deformation of the subducting Nazca Plate by determining high-quality earthquake locations, slab contours, and focal mechanisms. Our results suggest that the subduction of the incoming Juan Fernandez Ridge controls the slab geometry and that ridge buoyancy and slab pull are key factors in the deformation of the slab. The spatial distribution of the slab seismicity suggests variability in the hydration state of the subducting Nazca Plate and/or in strain due to slab bending. These observations support the hypothesis that the along-trench variability in bathymetric features and hydration state of the incoming plate has profound effects in the subducting slab geometry and the upper plate structure in both flat and steeply dipping subduction zones.
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Parmhed, Oskar. "Near surface atmospheric flow over high latitude glaciers." Doctoral thesis, Stockholm University, Department of Meteorology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-197.
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<p>In this thesis various descriptions of the near surface atmospheric flow over a high latitude glacier is used in an effort to increase our understanding of the basic flow dynamics there.</p><p>Through their contribution to sea-level change, mountain glaciers play a significant role in Earth’s climate system. Properties of the near surface atmospheric flow are important for understanding glacier response to climate change.</p><p>Here, the near surface atmospheric flow is studied from several perspectives including the effects of both rotation and slope. Rotation is an important aspect of most atmospheric flows and its significance for mesoscale flows have gained recognition over the last years. Similarly, the very stable boundary layer (VSBL) has lately gained interest. Within a VSBL over sloping terrain katabatic flow is known to be usual and persistent. For the present thesis a combination of numerical and simple analytical models as well as observations from the Vatnajökull glacier on Iceland have been used. The models have continuously been compared to available observations. Three different approaches have been used: linear wave modeling, analytic modeling of katabatic flow and of the Ekman layer, and numerical simulations of the katabatic flow using a state of the art mesoscale model. The analytic models for the katabatic flow and the Ekman layer used in this thesis both utilizes the WKB method to allow the eddy diffusivity to vary with height. This considerably improves the results of the models. Among other findings it is concluded that: a large part of the flow can be explained by linear theory, that good results can be obtained for surface energy flux using simple models, and that the very simple analytic models for the katabatic flow and the Ekman layer can perform adequately if the restraint of constant eddy diffusivity is relieved.</p>
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Foster, Kristi A. "Field Ecology Patterns of High Latitude Coral Communities." NSUWorks, 2011. http://nsuworks.nova.edu/occ_stuetd/82.
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Some climate models predict that, within the next 30-50 years, sea surface temperatures (SSTs) will frequently exceed the current thermal tolerance of corals (Fitt et al. 2001; Hughes et al. 2003; Hoegh-Guldberg et al. 2007). A potential consequence is that mass coral bleaching may take place (i) during warm El Niño-Southern Oscillation (ENSO) events which are predicted to occur in some regions more frequently than the current 3-7 year periodicity (Hoegh-Guldberg 1999; Sheppard 2003) or (ii) perhaps as often as annually or biannually if corals and their symbionts are unable to acclimate to the higher SSTs (Donner et al. 2005, 2007). Global data also indicate an upward trend toward increasing frequencies, intensities, and durations of tropical hurricanes and cyclones (Emanual 2005; Webster et al. 2005). As coral communities have been shown to require at least 10-30 years to recover after a major disturbance (e.g. Connell 1997; Ninio et al. 2000; Bruno & Selig 2007; Burt et al. 2008), it is possible that future coral communities may be in a constant state of recovery, with regeneration times exceeding the periods between disturbances. Life history traits (e.g. reproduction, recruitment, growth and mortality) vary among species of hard corals; thus, gradients in community structures may have a strong influence on susceptibilities to disturbance and rates of recovery (Connell 1997; Ninio & Meekan 2002). Taxa which are more susceptible to bleaching and mechanical disturbance (e.g. tabular and branching acroporids and pocilloporids) may experience continual changes in population structure due to persistent cycles of regeneration or local extirpation, while the more resistant taxa (e.g. massive poritids and faviids) may display relatively stable population structures (Woodley et al. 1981; Hughes & Connell 1999; Baird & Hughes 2000; Marshall & Baird 2000; Loya et al. 2001; McClanahan & Maina 2003). Determining whether resistant coral taxa have predictable responses to disturbances, with consistent patterns over wide spatial scales, may improve predictions for the future affects of climate change and the composition of reefs (Done 1999; Hoegh-Guldberg 1999; McClanahan et al. 2004).
The work presented in this dissertation describes the spatial and temporal patterns in community structures for high latitude coral assemblages that have experienced the types of natural disturbances which are predicted to occur in tropical reef systems with increasing frequency as a result of climate change. The primary area of focus is the southeastern Arabian Gulf, where the coral communities are exposed to natural conditions that exceed threshold limits of corals elsewhere in the world, with annual temperature ranges between 14-36°C (Kinzie 1973; Shinn 1976) and salinities above 40 ppt. Two additional regions are included in this study for comparisons of high latitude coral community structures. The northwestern Gulf of Oman is adjacent to the southeastern Arabian Gulf (i.e. the two bodies of water are connected by the Strait of Hormuz); however, the environmental conditions are milder in the Gulf of Oman such that the number of coral taxa therein is threefold that found in the southeastern Arabian Gulf (i.e. 107 coral species in the Gulf of Oman compared to 34 species in this region of the Arabian Gulf (Riegl 1999; Coles 2003; Rezai et al. 2004)). Broward County, Florida is geographically remote from the Gulfs and, therefore, serves as a benchmark for testing whether consistent patterns in community structures exist despite different climatic and anthropogenic influences.
The coral communities within the southeastern Arabian Gulf, the northwestern Gulf of Oman, and Broward County, Florida have been exposed to recurrent elevated sea surface temperature (SST) anomalies, sequential cyclone and red tide disturbances, and frequent hurricanes and tropical storms, respectively. These disturbances and other impacts (e.g. bleaching episodes, disease outbreaks, anthropogenic stresses) have affected the more susceptible acroporids and pocilloporids, resulting in significant losses of coral cover by these families and shifts towards massive corals as the dominant taxa. During the post-disturbance scarcity or absence of branching and tabular corals, the resistant massive taxa have become the crux of the essential hard coral habitat for fish, invertebrates and other marine organisms.
Because recovery to pre-disturbance community structures may take decades or may not occur at all, it is vital that scientists and resource managers have a better understanding of the spatial and temporal ecology patterns of the corals that survive and fill in the functional gaps that are created by such disturbances. To aid in this understanding, this dissertation presents spatial and temporal patterns for the coral assemblages which have developed after the respective disturbances. Spatial ecology patterns are analyzed using graphical descriptions (e.g. taxa inventories, area cover, densities, size frequency distributions), univariate techniques (e.g. diversity indices), distributional techniques (e.g. k-dominance curves) and multivariate techniques (e.g. hierarchical clustering, multidimensional scaling). Temporal comparisons at monitoring sites within the southeastern Arabian Gulf and northwestern Gulf of Oman describe the coral population dynamics and are used to create size class transition models that project future population structures of massive corals in the recovering habitats.
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Hansen, Christel Dorothee. "On high-altitude and high- latitude frost environments." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/62383.
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Frost environments occur throughout the world, with associated processes occurring across climatic zones. Climatic geomorphology proposes that climatic zones, largely derived from annual average air temperature and precipitation values, have specific landforms and processes active within that zone. This study offers unique insights into the frost environments of three locations in the Southern Hemisphere, namely the Eastern Cape Drakensberg of South Africa, sub-Antarctic Marion Island, and Dronning Maud Land of Antarctica. The Drakensberg ranges from temperate to alpine, Marion Island is hyper-maritime, and Dronning Maud Land a polar desert. Drivers and forcings on the ground frost regime are identified, as are future climatic scenarios. Altitude and latitude were identified as the most important locational drivers, while air temperature showed highest correlation with freezing events. The initiation of a freeze event correlated strongly with maximum ground temperatures. Vegetation cover was found to ameliorate frost cycles, thereby increasing ground temperatures. Dronning Maud Land of Antarctica is characterised by annual frost (permafrost), with limited seasonal thaw in summer. Thawing cycles reflected the depth of the active layer, which ranged from just under 60 cm for Robertskollen (at lowest altitude) to less than 15 cm on Slettfjell (at greatest altitude). Marion Island had the most active frost environment, exhibiting both seasonal frost, and ubiquitous shallow diurnal frost cycles. The Drakensberg were largely frost-free, with limited seasonal frost and few diurnal freeze- thaw events. Diurnal frost processes were found to be azonal, and present at all three study locations. Evidence of landforms derived from diurnal frost processes were evident in each zone. Equifinality/convergence of form was present to a degree. The presence of patterned ground, which was not wholly derived from frost processes, suggests a measure of equifinality. Furthermore, openwork block deposits, of which not all are either blockstreams nor blockfields, are not necessarily the result of frost processes. The periglacial environment is poorly defined and methods to delineate this environment, as well as other climatic zones, should include additional parameters. Delineating zones on annual (and limited) monthly averages based on predominantly temperature, is not sufficient. While concepts of climatic geomorphology may be applied in a general sense, this framework is not suited to working at smaller scales. Specifically, periglacial environments should be delineated using ground moisture, as well as air temperature. Furthermore, vegetation and snow cover are important, as are soil textural properties.
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Adamson, Daniel Stephen. "Boundary layer frictional processes in mid-latitude cyclones." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393529.
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This Thesis develops understanding of the physical mechanisms responsible for the frictional effects observed in cyclone development. To do this, a first-order closure mixing-length boundary layer scheme has been added to a baroclinic life cycle model to accurately represent the frictional processes occurring in cyclone development. Life cycles simulated with the model consist of normal mode baroclinic growth with cyclone development followed by barotropic decay. By considering life cycles where friction is the only diabatic process, it is found that surface drag reduces rates of baroclinic growth and barotropic decay by 40%. The classical description of frictional effects in rotating geophysical flows involves the Ekman spin-down of a barotropic vortex. This mechanism is studied by considering the quasi-geostrophic w-equation with a frictional term. However, these barotropic vortex ideas do not account for the baroclinic processes occurring, especially within the frontal regions. To address these shortcomings, a potential vorticity (PV) approach is adopted. Large frictionally generated positive PV anomalies form close to developing warm and cold fronts, due to the relative alignment of surface and thermal wind vectors. These PV anomalies are advected upwards and polewards along the warm conveyor belt and then westwards. This results in a band of positive PV associated with high static stability in the lower troposphere above the surface low centre. Using Rossby edge wave theory, a mechanism is proposed to explain the reduced baroclinic development observed in terms of this positive PV anomaly. Hence the baroclinic dynamics are shown to play a crucial role in the frictional modification of cyclone development. The classical notion of Ekman spin-down is shown to be of secondary importance. This mechanism by which frictional processes reduce cyclone development is found also to be valid in the presence of sensible and latent heat fluxes.
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Koh, Tieh-Yong 1972. "Isentropic diagnostics of mid-latitude circulation and transport." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/59649.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.<br>Includes bibliographical references (p. 279-287).<br>This thesis examines the mid-latitude circulation and tracer transport using zonal average isentropic diagnostics. The Underworld (i.e. the region roughly below the 300K-isentrope) is targeted by our research. Currently, there is a lack of rigorous and consistent theoretical formalism to deal with isentropes that intersect the Earth's surface. In this thesis, we develop such a formalism and use it to address three main questions: (1) How is the mean circulation forced by the eddies in the region - dubbed "surface zone" - where isentropes intersect the surface in the longitude-height plane? (2) What are the pathways of global chemical transport due to mean circulation and eddies? (3) How are eddy chemical and PV transports related? A primitive-equation model on a sphere, equipped with simple physical parametrizations and on-line tracer transport, is used to investigate these questions. We tackle question (1) by looking for explanations in terms of angular momentum balance and surface heat transport. Our results show that equatorward PV flux forces a poleward mean flow in the warmer region of the surface zone. In the colder region, an equatorward mean flow is forced by eastward surface form drag, which is attributed to poleward eddy heat, flux at the surface.<br>(cont.) We also evaluate and modify the kinematic explanation put forth by Held and Schneider (1999). As regards question (2), we found that idealized chemical tracers released into the planetary boundary layer (PBL) are transported equatorward in the surface zone by the mean circulation and the eddies. Some are recirculated polewards by the eddies, both along the surface and along isentropes (in the absence of latent heat release). Mid-tropospheric tracers are adiabatically transported by eddies into the mid-latitude PBL. Question (3) is addressed using a diffusive formulation for isentropic eddy transport. The eddy-diffusion coefficients for several idealized chemicals of lifetime 20 days agree rather well, demonstrating the usefulness of the parametrization. But the eddy-diffusion coefficient for PV, while showing the same enhancement at steering levels, is sufficiently different from chemical eddy-diffusion coefficients to imply that diabatic heating is significant in a baroclinic wave.<br>by Tieh-Yong Koh.<br>Ph.D.
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Davies, Jacqueline Anne. "Ion frictional heating in the high-latitude ionosphere." Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/35864.
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At auroral latitudes, large electric fields drive the F-region plasma of the ionosphere through the thermosphere, heating the ion population through frictional contact with the neutral gas. Ion frictional heating, which can double the unperturbed ion temperature, is an important manifestation of both magnetosphere-ionosphere and ionosphere-thermosphere interaction and provides a significant contribution to the energy budget of the ionosphere and neutral atmosphere at high-latitudes. Perhaps the single most powerful technique for ground based remote sensing of the ionosphere is incoherent scatter. The EISCAT radar facility, located in northern Scandinavia, employs this technique to investigate the highly dynamic nature of the high-latitude ionosphere. This thesis documents a study of ion frictional heating in the high-latitude ionosphere, principally employing common programme observations by the tristatic EISCAT UHF system. In excess of 3200 hours of EISCAT observations, taken during a six year period, were employed to study, on a statistical basis, ion frictional heating in the high-latitude F-region. The diurnal distribution of frictional heating was established and its dependence on such factors as geomagnetic activity and solar cycle was investigated; the distributions were interpreted with reference to corresponding distributions of enhanced ion velocity. A prolonged and intense interval of ion frictional heating was observed by EISCAT postnoon on 04/03/1992: this interval was modelled, using the Sheffield University plasmasphere and ionosphere model, and the model results compared with the observations. This study highlights the importance of ionospheric effects in determining neutral dynamics, particularly on the dayside. Furthermore, during this interval, the altitude dependence of the effect of enhanced electric fields on the velocity and temperature of the ion population was studied and, moreover, employed to provide first-order estimates of the normalised ion-neutral collision frequency and the neutral wind at E-region altitudes.
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Bronselaer, Benjamin. "Climate-carbon feedback of the high latitude ocean." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:2b02901a-6332-438c-a113-789bce211c71.
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The warming induced by anthropogenic carbon emissions affects the climate system through a multitude of physical mechanisms. Changes in the dynamics, thermodynamics and biogeochemistry of the ocean alter the different ocean carbon reservoirs, potentially resulting in further carbon emissions and a climate- carbon feedback. Surface wind stress and surface warming are two of the most influential forcings acting on the ocean carbon system in past, present and future climates due to their influence on the mixed layer dynamics and the large scale ocean circulation. This thesis quantifies the climate-carbon feedback of wind stress and surface warming, with a particular focus on the mechanisms driving the feedbacks and the role of the Southern Ocean and the North Atlantic. To study the feedbacks, a set of theoretical scalings and a hierarchy of numerical simulations are used. Of the climate feedbacks examined, increased surface warming is likely to result in large atmospheric CO<sub>2</sub> anomalies while the effects of North Atlantic wind stress are likely to be negligible. The atmospheric feedback of surface warming is constrained by compensating changes in separate ocean carbon reservoirs as a result of warming-induced circulation changes. Southern Ocean winds affect atmospheric CO<sub>2</sub> through both local upwelling of carbon as well as the remote modification of Equatorial and North Atlantic chemistry. As a result, the net Southern Ocean wind stress feedback could be significant and even comparable to the temperature feedback. This thesis provides a quantification of regional and global climate-carbon feedbacks due to ocean dynamics. The estimates of carbon-climate feedbacks are useful tools for understanding past, present and future climates.
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Trabulsi, Hussein. "Politique monétaire au Liban : entre latitude et gouvernance." Dijon, 2005. http://www.theses.fr/2005DIJOE008.
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MOUNIR, HASSANE. "La turbulence electrostatique dans l'ionosphere a haute latitude." Paris 6, 1989. http://www.theses.fr/1989PA066360.
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Des champs electriques turbulents de basse frequence ont ete observes par le satellite aureol-3 dans toute l'ionosphere a haute latitude et dans la gamme d'altitudes 400-2000 km. Trois modeles theoriques de turbulence ont ete proposes en se basant sur la forme des spectres et sur les sources d'energie libre disponibles. La premiere, due a l'evolution non lineaire de l'instabilite de derive de gradient, est caracterisee par une amplitude relative faible et des indices spectraux de l'ordre de 1. 8. La composante electrique perpendiculaire au champ magnetique est plus importante que la composante parallele. La seconde est observee en presence de courants paralleles de faible et moyenne intensite et de gradients de densite. Les indices spectraux des fluctuations du champ electrique et de la densite sont du meme ordre que dans le cas precedent. Par contre l'amplitude de la composante electrique parallele devient plus grande. Finalement, en presence de cisaillements de vitesse, de flux d'electrons et de courants paralleles intenses, l'amplitude de la turbulence devient tres grande avec dans la plupart des cas une composante electrique parallele superieure a la composante perpendiculaire. Les indices spectraux sont de l'ordre de 3. Une interpretation en terme d'instabilite k-h est justifiee par la presence du cisaillement de vitesse et par la comparaison avec les resultats de simulation numeriques. A l'aide du spectre en nombre d'onde deduit du spectre en frequences mesure, on a pu montrer le caractere bidimensionnel de la turbulence de derive du gradient
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Magnusson, Rebecca. "Effects of litter quality and latitude on decomposition." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-137763.
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Decomposition of organic material (litter) is an important part of the global carbon cycle. Environmental conditions, litter quality and the microbial community are the main factors affecting decomposition. The decomposition is divided into two phases, one fast initial phase and one slow second phase. The tea bag index (TBI) was used as a standardized method to measure decomposition rate along a latitudinal gradient. A common garden set up and extractions were made to determine the composition of the litter to investigate if climate or litter quality affected the decomposition rate. The result showed that the decomposition rate increased with higher latitude. The litter from higher latitude has more material that is easy to decompose. Natural litter abroad had higher decomposition rate than at home. On the contrary, standard litter at home had higher decomposition rate than abroad. This indicates that litter quality is more important than latitude. Further studies are needed with more sites along the gradient to conclude how climate and litter quality are affecting decomposition.
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Wohlwend, Christian Stephen. "Modeling the Electrodynamics of the Low-Latitude Ionosphere." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/11.
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The electrodynamics of the Earth's low-latitude ionosphere is dependent on the ionospheric conductivity and the thermospheric neutral density, temperature, and winds present. This two-part study focused on the gravity wave seeding mechanism of equatorial plasma depletions in the ionosphere and the associated equatorial spread F, as well as the differences between a two-dimensional flux tube integrated electrodynamics model and a three-dimensional model for the same time period. The gravity wave seeding study was based on a parameterization of a gravity wave perturbation using a background empirical thermosphere and a physics-based ionosphere for the case of 12 UT on 26 September 2002. The electrodynamics study utilized a two-dimensional flux tube integrated model in center dipole coordinates, which is derived in this work. This case study examined the relative influence of the zonal wind, meridional wind, vertical wind, temperature, and density perturbations of the gravity wave. It further looked at the angle of the wave front to the field line flux tube, the most influential height of the perturbation, and the difference between planar and thunderstorm source gravity waves with cylindrical symmetry. The results indicate that, of the five perturbation components studied, the zonal wind is the most important mechanism to seed the Rayleigh-Taylor instability needed to develop plasma plumes. It also shows that the bottomside of the F-region is the most important region to perturb, but a substantial E-region influence is also seen. Furthermore, a wave front with a small angle from the field line is necessary, but the shape of the wave front is not critical in the gravity wave is well developed before nightfall. Preliminary results from the three-dimensional model indicate that the equipotential field line assumption of the two-dimensional model is not valid below 100 km and possibly higher. Future work with this model should attempt to examine more of the differences with the two-dimensional model in the electric fields and currents produced as well as with the plasma drifts that lead to plume development.
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Davini, Paolo <1985>. "Atmospheric blocking and winter mid-latitude climate variability." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/2241.
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Atmospheric blocking is a mid-latitude weather pattern that describes a quasi-stationary, long-lasting, high-pressure system that modifies the westerly flow, blocking (or at least di- verting) the eastward movement of the migratory cyclones. Blocking events can have major impacts on the mid-latitude weather, sometimes leading to extreme events as cold spells in winter or heat waves in summer. In this thesis, Northern Hemisphere winter blocking and its impacts on mid-latitude climate are analyzed through the introduction of a set of new bidimensional diagnostics based on the geopotential height that provide information about the occurrence, the duration, the intensity and the wave breaking associated with the block- ing. We are able to distinguish among three main categories of blocking: one placed at low latitudes over the Pacific and Atlantic oceans, unable to block or divert the flow. A second one is detected at high latitude occurring over Greenland and North Pacific, north of the jet stream and dominated by cyclonic wave breaking. Finally a third category is defined as the traditional mid-latitude blocking, and it appears as being only localized over Europe and driven by anticyclonic wave breaking.
We address the relationship between the North Atlantic Oscillation (NAO) and the block- ing occurrence, showing that blocking over Greenland (Greenland Blocking, GB) is not only a key element to describe the NAO index, but it is essential also to modulate its pattern. Consistent with this, we link the eastward displacement of the NAO pattern observed in the recent years to the decreasing frequency of Greenland Blocking. On the other side, we notice that blocking events over Europe (European Blocking) are not correlated with the NAO. We also analyze the relationship between the Atlantic eddy driven jet stream dis- placements and blocking occurrence. We find that Greenland Blocking is linked with the equatorward displacements of the jet stream, while European Blocking is associated with poleward displacements of the jet (and only in some case it leads to a split flow).
In order to quantify the potential impacts of blocking changes in the future, global long- term climate projections from the Climate Model Intercomparison Project - Phase 5 (CMIP5) are analyzed. This is performed in order to understand the reasons behind the biases of the models and to evaluate the predicted change in blocking frequency and its pattern of variability in the next century. The majority of the state-of-the art models still exhibit large biases especially over Europe. In future climate scenario, the blocking frequency is predicted to decrease in association with an intensification and a reduction of variability of the Atlantic and Pacific jet streams.
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Cerqueira, Roberta Macedo 1976. "Padrões de variação da diverdidade alfa na floresta pluvial Atlântica brasileira." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314964.
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Orientador: Fernando Roberto Martins<br>Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia<br>Made available in DSpace on 2018-08-19T15:38:55Z (GMT). No. of bitstreams: 1
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Previous issue date: 2011<br>Resumo: Padrões de diversidade de espécies existem e são estudados em uma variedade de sistemas e escalas espaciais. Diferentes fatores geográficos e ambientais têm sido associados à variação na de diversidade em áreas florestadas, entretanto, ainda não existe um consenso na comunidade científica quanto à importância e à influência destes fatores em relação ao aumento ou diminuição da diversidade. Estudos pontuais de florística e fitossociologia no Brasil têm possibilitado o estabelecimento de alguns padrões e inferências sobre os fatores que afetam diretamente a diversidade dos sítios. A Floresta Ombrófila Densa ou Floresta Pluvial Atlântica (FPA) distribui-se ao longo de toda a costa brasileira. Apresenta elevada riqueza de espécies e um grande número de espécies endêmicas. Suas fitofisionomias são classificadas de acordo com a latitude e altitude em que ocorrem. Propomos neste estudo investigar os padrões de distribuição da diversidade alfa em sítios localizados em toda área de ocorrência da Floresta Pluvial Atlântica, procurando identificar centros de diversidade, a relação entre a distribuição da diversidade alfa e variáveis ambientais e a padrões de distribuição dos táxons (família, gêneros e espécies) ao longo da FPA. Utilizamos como medida de diversidade o índice de Shannon (H') e separamos as tabelas fitossociológicas por região geográfica. Os resultados apontaram para uma maior diversidade alfa na região sudeste brasileira, principalmente nos estados do Espírito Santo, São Paulo e Rio de Janeiro. Utilizamos regressões múltiplas e análises de correspondência canônica (CCA) para verificarmos correlações entre variáveis ambientais e índices de diversidade (H', ChaoI e C de Simpson). Nossos resultados demonstraram uma relação positiva entre latitude, altitude e longitude e os índices H' e ChaoI e uma relação negativa para C, em ambas as análises. Considerando os níveis taxonômicos analisados (família, gêneros e espécies), predominou o padrão de distribuição geográfica restrita. Myrtaceae apresentou a maior diversidade hierárquica e a maior constância relativa entre todas as famílias analisadas. Ocotea e Eugenia foram os dois únicos gêneros que apresentaram constância relativa acima de 80%. Dentre as espécies analisadas, nenhuma apresentou constância relativa >80%<br>Abstract: Patterns of species diversity exist and are studied within a variety of systems and spatial scales. Different geographical and environmental factors have been associated to the range of diversity in forest areas; however, there is of yet no consensus in the scientific community regarding the importance and the influence of these factors in relation to the increase or the decrease in diversity. Specific studies on floristics and phytosociology in Brazil have enabled establishing some patterns and inferences on the factors which directly affect the diversity in a particular site. The Atlantic Ombrophilous Dense Forest or the Atlantic Rain Forest (ARF) is distributed along the entire Brazilian coastline. It presents an abundance of species and an elevated number of endemic species. Its phytophysiognomies are classified according to the latitude and the altitude in which they occur. In this study we propose to investigate the patterns of distribution of the alpha diversity in sites located throughout the Atlantic Rain Forest, aiming at identifying centers of diversity, the relationship between the distribution of the alpha diversity and environmental variables and the patterns of distribution of taxons (family, genus and species) along the ARF. As a measurement of diversity, we used the Shannon Index (H') and we separated the sites according to geographical area. Results have shown a larger alpha diversity in the Southeast of Brazil, especially in the Espírito Santo, São Paulo e Rio de Janeiro states. We have used multiple regressions and Canonical Correspondence Analysis (CCA) to observe the correlation between environmental variables and diversity indices (H', Chao I and Simpson's C). Our results showed a positive relationship between latitude, altitude, longitude, and the H' and Chao I index and a negative relationship to C, in both analysis Considering the taxonomic levels that were analyzed (family, genus and species), a pattern of restricted geographical distribution was predominant. Myrtaceae presented larger hierarchical diversity and the highest relative constancy among all the families analyzed Ocotea and Eugenia were the only two genus which presented relative constancy higher than 80 %. Among the species analyzed, none presented relative constancy >80%<br>Doutorado<br>Biologia Vegetal<br>Doutor em Biologia Vegetal
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Stubbs, Timothy John. "Ion injection and transport in the high-latitude magnetosphere." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399080.
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Ritchie, Samuel Esteban. "The impact of SSC on high-latitude HF communications." Thesis, Lancaster University, 2009. http://eprints.lancs.ac.uk/28099/.
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Hibbert, Angela. "High latitude atmosphere-ocean coupling in sea level records." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539533.
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Griffin, Michael. "Comparison of high latitude thermospheric meridional neutral wind climatologies." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393707.
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Milan, Stephen. "Observations of HF radiowaves propagated over high latitude paths." Thesis, University of Leicester, 1994. http://hdl.handle.net/2381/35730.
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This thesis presents results from the NONCENTRIC experiment, conducted by the University of Leicester, in which five trans-auroral and polar cap HF propagation paths were monitored during two one-month campaigns. Signal strength, noise level, Doppler spreading and signal recognition were determined each hour on fourteen frequencies in the range 3 to 23 MHz. The diurnal variations in signal recognition and signal strength are consistent with the ionospheric changes produced by solar illumination. This behaviour is modified by processes occurring within the auroral zone and polar cap during disturbed geomagnetic conditions. Electron densities within the auroral ionosphere increase as a consequence of particle precipitation during disturbed conditions. Auroral enhancement of the D region attenuates signals on trans-auroral paths. This occurs in bursts with durations of tens of minutes, simultaneous with the occurrence of substorms. The magnitude of the absorption can be correlated with changes in the geomagnetic field at geosynchronous orbit. In contrast, enhanced electron densities within the auroral zone E and F regions increase the maximum frequency of propagation, especially at night, thus extending the propagation bandwidth. Within the winter polar cap ionosphere, sporadic high frequency propagation becomes possible from ionization patches convected from the dayside ionosphere. Prolonged periods of geomagnetic disturbance result in global changes in F region electron density, known as ionospheric storms. Four storms studied produce a decrease in the maximum usable frequency, a degradation of propagation reliability and, within the polar cap, an increase in the lowest usable frequency. Such periods of propagation degradation typically have a duration of five days, even during mild storm conditions. This comprehensive study of high latitude HF propagation has produced an improved understanding of the changes in the electron density of the polar ionosphere during both quiet and geomagnetically disturbed conditions.
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Millard, Genevieve Anne. "Numerical modelling of polar and middle latitude ozone loss." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619670.
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Cousins, C. R. "An astrobiological study of high latitude Martian analogue environments." Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19640/.
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The search for life on Mars is in part reliant on the understanding of Martian environments, both past and present, in terms of what life may inhabit these environments, how this life may be preserved in the rock record, and how this rock record may be detected during future missions to Mars. In particular, the upcoming European Space Agency mission ‘ExoMars’ has the primary aim to identify evidence of past or present life on Mars, and the work presented here is carried out within this context. Volcanism is a geological process common to both Earth and Mars, and this work sought to conduct a multidisciplinary astrobiological study of terrestrial volcanic and associated hydrothermal environments that exist geographically at high latitudes. Specifically, subglacial basaltic volcanic environments were explored in terms of phylogenetic diversity, preservation of biosignatures, and habitability under Martian conditions. Additionally, these and other volcanic environments were utilised in the development and testing of the Panoramic Camera – an instrument that will form an integral component of the ExoMars rover instrument suite. Results presented within this thesis demonstrate that subglacially erupted lavas provide a habitat for a diverse bacterial community, and that when such a community is subject to present-day Martian analogue conditions, survivability is significantly enhanced when a simulated subglacial volcanic system (i.e. heat and ice) is present. However, the generation of bioalteration textures – a biosignature common to glassy basaltic lavas – appears to be less common in subglacially-erupted lavas than their oceanic counterparts. Lastly, this work demonstrates the ability of the ExoMars PanCam in the detection of astrobiological targets, and shows the importance of utilising Martian analogue terrains both for biological studies, and also for testing rover instrumentation in preparation for upcoming missions.
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Pearce, Eiluned H. "The effects of latitude on hominin social network maintenance." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c51f63d2-6c07-46ec-81c8-8942afda8598.
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Social networks have been essential throughout hominin evolution, facilitating cooperative childrearing, transmission of cultural knowledge and the sharing of information and resources. As hominins dispersed out of Africa, these networks needed to be maintained at progressively higher latitudes. The first part of this thesis explores the impact of latitude on brain organisation and the possible implications for social cognition. I hypothesise that the lower temperatures and light levels found at higher latitudes select for larger bodies and visual systems, which in turn necessitate larger somatic and visual brain areas. Using orbit size to index eye and visual cortex size, I demonstrate a robust positive relationship between absolute latitude and orbit volume in recent humans. I show that Neanderthals, who solely inhabited high latitudes, have significantly larger orbits than contemporary anatomically modern humans (AMH), who evolved in lower latitude Africa and had only relatively recently dispersed into higher latitudes. Since Neanderthals and AMH dated 27-75kya have almost identical endocranial volumes, I argue that if a greater proportion of the Neanderthal brain was required for somatic and visual processing, this would reduce the volume of neural tissue available for other functions. Since, according to the Social Brain Hypothesis, neocortex volume is positively associated with social complexity, I propose that Neanderthals might have been limited to smaller social networks than AMH. The second part of the thesis explores the challenge of maintaining social networks across greater geographic distances at higher latitudes, where high travelling costs seem to prevent whole tribes from bonding during periodic aggregations. Using a gas model I predict that at lower latitudes daily subsistence mobility allows sufficient encounters between subgroups for the tribe to maintain connectivity, whereas in (Sub)Arctic biomes additional mechanisms are required to facilitate tribal cohesion. This may explain the apparent ‘explosion’ of Upper Palaeolithic art in Europe: symbolic representations allowed social ties to be sustained in the absence of frequent face-to-face contact. Overall, this thesis demonstrates that latitude may influence both brain organisation and cultural expression and argues that both can have a substantial impact on the maintenance of hominin social networks at high latitudes.
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Adhikari, Binod. "HILDCAA-related effects recorded in middle-low latitude magnetometers." Instituto Nacional de Pesquisas Espaciais (INPE), 2015. http://urlib.net/sid.inpe.br/mtc-m21b/2015/02.27.16.58.
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Disturbances of the geomagnetic field are caused by enhanced solar windmagnetosphere electrodynamical coupling process. The principal cause of geomagnetic disturbance is the magnetic reconnection between the southward directed interplanetary magnetic field component and the northward directed magnetopause field, that establishes an electrodynamic coupling between the solar wind plasma and magnetosphere. In general, this coupling is controled by dominant structures emanating from the sun like sporadic coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs), around the solar maximum, and by corotating high-speed streams, including corotating interaction region (CIR), in the descending and minimum phases of solar cycle. These high speed streams are embedded with highly fluctuating Alfven waves, which produce phenomena called HILDCAA events (high-intensity, long duration, continuous AE activity). This study investigates magnetic records from middle-low latitude geomagnetic observatories during HILDCAA periods. To this purpose, three primary conditions of the interplanetary space are considered: HILDCAA (i) not preceded by magnetic storm, (ii) preceded by storm generated by CIR, and (iii) preceded by storm generated by ICME. A fourth case is considered as a background condition: a geomagnetically quiet interval. As methodology of analysis, wavelet techniques to study multi-scale features of the HILDCAA events were explored in this work. The signal analyses techniques are composed by continuous wavelet transform, discrete wavelet transform, cross correlation using wavelet, and the usual modulus cross correlation. Complementarly, an evaluation on the field aligned currents (FAC) are considered in the investigation. Besides this, we estimate the polar cap potential (PCP) and merging electric field (Ey), and examine the role of PCP and geomagnetic AL index to monitor geomagnetic activity generated by geoeffective solar wind parameters during HILDCAAs. Thus, this work contributes to extend the understanding of HILDCAA events at higher latitudes to disturbances occurring at middle-low latitudes. There are magnetic effects related to the occurrence of HILDCAA even at middle-low latitudes.<br>Perturbações do campo magnético da Terra são causadas por intensificação de um processo de acoplamento eletrodinâmico entre o vento solar e a magnetosfera. A causa principal das perturbações geomagnéticas é a reconexão magnética entre o campo magnético interplanetário com orientação para o sul e o campo magnético da Terra orientado para o norte, que estabelecem um acoplamento eletrodinâmico entre o plasma do vento solar e a magnetosfera. Em geral, esse acoplamento é controlado por estruturas dominantes emanadas do Sol como ejeções de matéria coronal (CMEs) e suas contrapartes interplanetárias (ICMES), em torno do máximo solar, e por feixes de alta velocidade corrotantes, incluindo regiões corrotantes de interação (CIR), nas fases descendente e de mínimo do ciclo solar. Esses feixes de alta velocidade portam ondas alfvênicas com intensa flutuação dos parâmetros físicos do plasma, que produzem os fenômenos de atividade AE continuada de alta intensidade e de longa duração, denominados eventos HILDCAA (high-intensity, long duration, continuous AE activity). Este estudo investiga os registros magnéticos obtidos de observatórios geomagnéticos durante períodos de HILDCAA. Para esse propósito, três condições fundamentais do espaço interplanetário são consideradas: HILDCAA (i) não precedida de tempestade geomagnética; (ii) precedida por tempestade gerada por CIR; e (iii) precedida por tempestade gerada por ICME. Um quarto caso é considerado como uma condição de ambiente de fundo: um intervalo geomagneticamente calmo. Como metodologia de análises, técnicas wavelets para estudar características multiescalas dos eventos HILDCAAs são exploradas neste trabalho. As técnicas de análises de sinais são compostas pela transformada wavelet contínua, transformada wavelet discreta, correlação cruzada usando wavelet, e a usual correlação cruzada das intensidades dos sinais. De maneira complementar, uma avaliação das correntes elétricas alinhadas com o campo geomagnético são consideradas na investigação. Além disso, estimamos o potencial na região polar (polar cap potential, PCP) e o campo elétrico resultante da reconexão magnética (Ey), e examinamos o papel do PCP e do índice geomagnético AL para monitorar a atividade geomagnética produzida pelos parâmetros solares geoefetivos durante os eventos HILDCAAs. Assim, este trabalho contribuiu para estender a compreensão dos eventos HILDCAAs de altas latitudes para distúrbios ocorrendo em médias e baixas latitudes. Há efeitos magnéticos relacionados a ocorrências de HILDCAAs mesmo em baixas e médias latitudes.
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Knowland, Katherine Emma. "Linking mid-latitude storms, atmospheric composition and climate variability." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/15975.
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In this thesis, the role of mid-latitude cyclones in air pollution transport in the Northern Hemisphere is quantified. The storm tracking model, TRACK, is used to study the mechanisms through which pollution, specifically ozone (O3) and carbon monoxide (CO), are vented from the boundary layer to the free troposphere and thus transported over large distances, as well as the introduction of O3 from the stratosphere into the troposphere. The relationship between mid-latitude cyclones and air pollution transport of O3 and CO is explored for the first time using the Monitoring Atmospheric Composition and Climate (MACC) reanalysis, a combined meteorology and composition reanalysis dataset. A comparison between springtime surface ozone measurements at rural background sites on the west coast of Europe and cyclone track frequency in the surrounding regions was used to first establish the correlation between cyclone location and surface air quality. The focus is on spring as it tends to be the season of maximum intercontinental transport of O3. The surface observations were compared to the MACC O3 values at the same locations and case studies of how cyclones can influence surface O3 measurements are described. When cyclones track north of 53°N, there is a significant probability that the surface O3 will be high (> the 75th percentile), due to the close proximity to stratospheric intrusions and the transport at low levels across the North Atlantic Ocean. The most intense spring cyclones (95th percentile) were selected for two regions, the North Atlantic and the North Pacific, for further investigation into the mechanisms which impact O3 and CO concentrations near cyclones. These intense cyclones ( 60 over each region) often tracked over the major emission sources of eastern North America and East Asia. The distributions of MACC O3 and CO within a "typical" intense cyclone are examined by compositing the cyclones together. The cyclone-centered composites were compared to background composites of "average conditions" created by sampling the reanalysis data of the previous year to the cyclone locations. Mid-latitude cyclones are found to redistribute concentrations of O3 and CO horizontally and vertically throughout the cyclone. This is clearly shown to occur through two main mechanisms: (1) vertical lifting of CO-rich and O3-poor air isentropically from near the surface to the mid- to upper-troposphere in the region of the warm conveyor belt; and (2) descent of O3-rich and CO-poor air isentropically in the vicinity of the dry intrusion, from the stratosphere toward the mid-troposphere. This work was expanded to identify the links between teleconnection patterns, mainly the North Atlantic Oscillation (NAO), that affect the major storm track pathways in the North Atlantic sector and the distribution of MACC O3 and CO throughout the troposphere and lower stratosphere. For this analysis, TRACK was used to calculate seasonal weighted-average O3 and CO distribution maps based on the monthly NAO index. During positive NAO phase, the persistence of low pressures over the North Atlantic coupled with the Azores High promotes transport across the North Atlantic throughout the troposphere. During negative NAO phase, blocking high pressure in the eastern North Atlantic are known to occur, which shifts transport pathways to a more southerly zonal flow. This work demonstrates the complex relationship between the horizontal and vertical distribution of pollution, including surface concentrations, and synoptic-scale systems.
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Nakakushi, Takashi. "Observational studies of the Martian low-latitude cloud belt." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/64949.
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