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Dissertations / Theses on the topic 'Synoptic climatology'
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1
Caruso, Steven J. "Synoptic climatology of subtropical cyclogenesis." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7024.
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During the Hawaiian cool season (October - April), upper-level lows sometimes become cut off from the polar westerlies south of 30°N latitude in central Pacific. Seventy such lows formed during the years 1980-2002. There is strong inter-annual variability in their frequency, with an average of ~3 lows per season. The number of lows decreased during the 3 strongest EI Nino seasons and increased during the 3 strongest La Nina seasons, with statistically significant excursions. Low formation is greatest during October and November, when storm genesis is concentrated to the west-northwest of the Hawaiian Islands. Low genesis shifts eastward through the cool season, favoring the area to the east-northeast of Hawaii during February and March, consistent with the shift in the climatological position of trough aloft during the cool season. Out of a total of 70 upper-level lows, 43 were accompanied by surface cyclogenesis and were classified as kona lows. Kona-Iow formation is concentrated to the west-northwest of Hawaii, whereas lows without surface development are concentrated in the area to the east-northeast of Hawaii. Analysis reveals several distinctions between the kona lows and the lows without surface development. Surface deepening correlates strongly with positive vorticity advection by the thermal wind. Surface deepening also correlates with potential vorticity on the 340-K isentropic surface and the maximum v-component of the wind aloft. Static stability and advection of low level moisture are less strongly correlated to surface deepening. These results confirm that kona-Iow formation, to first order, is driven be upper-level forcing that originates in the midlatitudes, and that convection and latent heat release playa secondary role.vii 49 leaves
2
Fischer, Alexandre P. "A synoptic climatology of Montreal precipitation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0022/MQ50767.pdf.
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Betts, Nicholas Leonard. "A synoptic climatology of precipitation in Northern Ireland." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335059.
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Hawksworth, Kevin. "The synoptic climatology of daily precipitation in Wales." Thesis, University of Wales Trinity Saint David, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683158.
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Badger, Jake. "Mechanisms for rapid synoptic development." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363836.
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Sepp, Mait. "Influence of atmospheric circulation on environmental variables in Estonia /." Tartu, Estonia : Tartu University Press, 2005. http://dspace.utlib.ee/dspace/bitstream/10062/1080/5/sepp.pdf.
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Karmosky, Christopher. "Synoptic climatology of snowfall in the northeastern United States an analysis of snowfall amounts from diverse synoptic weather types /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 166 p, 2008. http://proquest.umi.com/pqdweb?did=1459905421&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Lewis, Simone L. "A synoptic climatology of significant snow producing synoptic scale events in central Indiana, 1974-2003." Virtual Press, 2005. http://liblink.bsu.edu/uhtbin/catkey/1328117.
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The relationship between specific synoptic and mesoscale snowfall producing system types and their associated mean upper-level flow patterns are examined to determine their impacts on snowfall magnitudes in central Indiana. Chi-square and ANOVA tests are conducted to determine the relationship of the 850mb temperature, the 1000-500mb thickness, 500mb flow pattern, and phase of the Southern Oscillation Index to snowfall amounts for the period of record 1974-2003. Results suggest that variables such as the 1000-500mb thickness, system type, and phase of the Southern Oscillation Index do affect the magnitude of snowfall in central Indiana on a variety of temporal scales ranging from days to entire seasons.Department of Geography
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Surprenant, Jeremy Lee. "A Synoptic Climatology of Wildfires in the Midwestern United States." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/467.
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Predicting wildfire activity has been a major concern for fire weather forecasters and fire managers in recent decades. Identifying mid-tropospheric circulation patterns that are conducive to higher rates of spread has been widely employed as a predictive tool. This study classifies circulation patterns at the 500 mb level for 3865 fire days from 1970 through 2004 in the central hardwood region of the Midwestern United States. Several circulation patterns were identified that are associated with enhanced fire activity relative to other patterns. All patterns with elevated fire activity were associated with either flow from dry air source regions, or patterns that placed the region on the periphery of a high pressure system. Weather variables associated with each type of circulation pattern were also analyzed and were found to vary among patterns. Circulation patterns with greater fire activity were identified as being drier than patterns with lesser activity. The findings of this study provide crucial information to fire managers and forecasters, which can help them achieve their ultimate goal of minimizing loss of life and property.
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Perry, Lester Baker Konrad Charles Edward. "Synoptic climatology of northwest flow snowfall in the southern Appalachians." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,165.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Geography (Climatology)." Discipline: Geography; Department/School: Geography.
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Stephens, Kate 1968. "A synoptic climatology of ground-level ozone for Montreal, Quebec." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22811.
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A mean sea level (MSL) and 500 hPa height field synoptic climatology of ozone is developed for the Montreal region over the period 1980-1992 using the Kirchhofer computer-assisted map-pattern technique. Synoptic class air quality signatures are examined on an annual, seasonal and interannual basis. Residual cumulative dose analysis confirms that the "Back of the High" synoptic types are responsible for above average ozone concentrations in the summer months. In contrast, during the winter, the stable conditions and cold temperatures associated with these same synoptic types promote ozone scavenging and below average ozone concentrations. Above average winter ozone levels are associated with cyclonic synoptic types, possibly as a result of stratospheric ozone intrusion. Synoptic sequencing confirms the importance in stability in upper level features (particularly an upper level trough to the northeast of Montreal) and stagnation of surface features (primarily the "Back of the High") for the development of elevated ozone concentrations in Montreal. Finally, a declimatizing technique is evaluated as a means of removing the synoptic signal from the ozone time series. Results of this study are in broad agreement with similar investigations elsewhere in northeastern North America.
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Lamakin, Mikhail. "Synoptic climatology of aerosol optical depth in the Eurasian Arctic." Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414600.
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O'Hara, Brian F. "A synoptic climatology of heavy snowfall in the Sierra Nevada, USA." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446431.
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Spellman, Greg. "An evaluation of statistical synoptic models of rainfall in Spain." Thesis, University of Northampton, 2003. http://nectar.northampton.ac.uk/2997/.
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This study investigates the control of atmospheric circulation patterns on rainfall incidence in Spain. The main objective of the research is to evaluate a range of statistical synoptic approaches with the aim of identifying the scheme that best models circulation to association. Spatial patterns of rainfall in Spain are first investigated using Principal Components Analysis and Cluster Analysis. Distinct precipitation affinity groups emerge that display covariant rainfall behaviour and reflect differences in latitude, the influence of topography and distance from the synoptic feature responsible for rainfall. The method allows seasonal redefinition of boundaries and the investigation of the effect of climate change. In total 24 synoptic models are investigated. The best performing models (a daily weather type model and a monthly airflow index model) use standardized data and the 500hPa contour surface. Some of the problems associated with non-stationarity are attempted by modifying models using kinematic information. Adjustments to the models (inclusion of frontal information and stochastic modelling) can improve results on a sub-regional scale. Effective models are then used to empirically downscale from General Circulation Model (GCM) scenarios obtained from the Canadian Centre for Climate Modelling and Analysis. The downscaling procedure is of limited use due to errors in GCM output but results suggest strongly increasing anticyclonicity in the Iberian area and a decrease in rainfall in many areas. There are uncertainties associated with regional scale climate change estimation using current empirical methods, nevertheless as GCM output inevitably becomes more accurate the scope for detailed regional assessment will improve
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Nazarenko, Dennis Matthew. "Synoptic scale ice-atmosphere interaction off the east coast of Canada." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59425.
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Seasonal ice cover off Canada's east coast was examined in relation to synoptic scale atmospheric events. Ice concentration information derived from Nimbus-7 scanning multichannel microwave radiometer (SMMR) measurements of surface brightness temperatures, supplemented by AES composite ice charts, provided timely coverage of the study area during the 1971/72, 1980/81 and 1984/85 ice seasons, 1971/72 and 1984/85 seasons with high ice concentrations and 1980/81 a season with low concentrations.Atmospheric variability was monitored using the 850 hPa height at three upper air stations along the western edge of the study region. Additional information was drawn from storm track records, providing an indication of surface variability. Properties of specific storm events were obtained from the storm track data, permitting evaluation of the ice response to passing synoptic disturbances.
Results of this investigation indicate that, (1) passive microwave-derived ice information can be used to monitor high frequency variability in the marginal ice, (2) despite short time series, spectral relationships between ice concentration variability and 850 hPa pressure height indicate a strong association between the two at synoptic frequencies zone, and (3) variability in ice cover extent and concentration can be related to the passage of individual synoptic events.
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Paxton, Andrew Blair. "Extreme Precipitation in Illinois: Trend Estimation and Relation with Large-Scale Circulation and Humidity." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2877.
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Extreme precipitation in Illinois contributes to impacts across diverse landscapes, posing threats to agriculture in rural areas and infrastructure in urban centers. Previous studies have reported an increase in the frequency of heavy precipitation in the region and projected its amplification under climate change. However, these findings are often characterized by inconsistent and/or inappropriate approaches for estimating historical trends and their significance and often lack process-based understanding regarding future changes in extreme event climatology. This study aims to obtain robust regional extreme precipitation trends and relate those trends to large-scale circulation and humidity. The climatology and trends of daily extreme precipitation are established by applying a peaks-over-threshold approach to the newly developed NOAA NCEI nClimGrid-D dataset which includes daily precipitation totals at 5-km resolution. For trend estimation, we use Theil-Sen estimation with three approaches designed to emphasize correction of inflation in the significance of the estimated trends: (1) a “naïve” approach in which we simply consider the direct output of the Theil-Sen method and assess significance using a traditional Mann-Kendall test, (2) an approach based on a modified Mann-Kendall test to account for serial autocorrelation in the assessment of significance, and (3) an approach that also controls for the false discovery rate associated with a large number of tests by considering field significance. To relate these trends to large scale drivers, a multivariate self-organizing map is constructed based on standardized 500 mb geopotential height and 850 mb specific humidity obtained from the ECMWF ERA-5 reanalysis dataset. We use a Monte Carlo experiment to identify weather types most associated with extreme precipitation in the area. Temporal and spatial characteristics of the identified weather types are then analyzed to better understanding their role in changes in the frequency of extreme precipitation events across the region. As expected, the results indicate a stark contrast between the naive and more complex approaches for significance testing, where controlling for autocorrelation and test multiplicity reduces the spatial extent of significant trends across all extreme precipitation thresholds. Extreme precipitation in Illinois is found to be associated with a small number of specific weather types characterized by distinct patterns of geopotential height and humidity. Furthermore, the weather types most frequently associated with extreme precipitation are increasing in frequency, suggesting that changes in atmospheric circulation related to moisture transport and convergence are a major contributor to changes in extreme precipitation in Illinois.
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Walls, Kristin Ashley. "Synoptic Analysis of the Tornado and Derecho Climatology of Ohio from 1963-2002." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250265230.
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Surprenant, Jeremy L. "A synoptic climatology of wildfires in the central hardwood region of the Midwestern United States /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1796120971&sid=6&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Lukancic, Khara Diane. "SENSITIVITY OF STRONG EXTRATROPICAL CYCLONES TO LARGE-SCALE CLIMATE VARIABILITY IN THE CONTIGUOUS UNITED STATES." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2043.
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Extratropical cyclones are responsible for a substantial portion of midlatitude climate variability and contribute to widespread impacts. The characteristics of extratropical cyclones, such as their spatial distribution and intensity, are thought to be dependent on the large scale circulation. The relationship between cyclone characteristics and modes of large-scale climate variability has been investigated in previous studies, but interactions between modes of climate variability have largely been ignored. Since extratropical cyclone characteristics may be related to interactions between phases, quantifying these relationships is an important step in improving the climatology of extratropical cyclones. The goal of this study is to quantify relationships between modes of climate variability and characteristics of strong cyclones in the contiguous United States. Using historical sea-level pressure data, cyclone intensity, frequency, and spatial distribution are investigated using a cyclone definition that combines the requirement for low pressure (1000 hPa or lower) and positive (cyclonic) vorticity. The large scale modes of climate variability considered include El Niño Southern Oscillation (ENSO), the Pacific North American (PNA) mode, and the Arctic Oscillation (AO). The analysis is divided into three phases focusing on (1) establishing a background cyclone climatology within the study area, (2) quantifying differences in cyclone characteristics between the positive and negative phases of the individual modes of climate variability, and (3) examining the interactions between the modes of climate variability as they relate to extratropical cyclone characteristics. The results are expected to provide an improved baseline for evaluation of coupled climate models and also have the potential to improve seasonal climate predictability.
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Matthews, Tom K. R. "Glacier-climate interactions : a synoptic approach." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12558.
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The reliance on freshwater released by mountain glaciers and ice caps demands that the effects of climate change on these thermally-sensitive systems are evaluated thoroughly. Coupling climate variability to processes of mass and energy exchange at the glacier scale is challenged, however, by a lack of climate data at an appropriately fine spatial resolution. The thesis addresses this challenge through attempting to reconcile this scale mismatch: glacier boundary-layer observations of meteorology and ablation at Vestari Hagafellsjökull, Iceland, and Storglaciären, Sweden, are related to synoptic-scale meteorological variability recorded in gridded, reanalysis data. Specific attention is directed toward synoptic controls on: i) near-surface air temperature lapse rates; ii) stationarity of temperature-index melt model parameters; and iii) glacier-surface ablation. A synoptic weather-typing procedure, which groups days of similar reanalysis meteorology into weather categories , forms the basis of the analytical approach adopted to achieve these aims. Lapse rates at Vestari Hagafellsjökull were found to be shallowest during weather categories characterised by warm, cloud-free weather that encouraged katabatic drainage; steep lapse rates were encountered in weather categories associated with strong synoptic winds. Quantitatively, 26% to 38% of the daily lapse-rate variability could be explained by weather-category and regression-based models utilizing the reanalysis data: a level of skill sufficient to effect appreciable improvements in the accuracy of air temperatures extrapolated vertically over Vestari Hagafellsjökull. Weather categories also highlighted the dynamic nature of the temperature-ablation relationship. Notably, the sensitivity of ablation to changes in air temperature was observed to be non-stationary between weather categories, highlighting vulnerabilities of temperature-index models. An innovative solution to this limitation is suggested: the relationship between temperature and ablation can be varied as a function of weather-category membership. This flexibility leads to an overall improvement in the simulation of daily ablation compared to traditional temperature-index formulations (up to a 14% improvement in the amount of variance explained), without the need for additional meteorological data recorded in-situ. It is concluded that weather categories are highly appropriate for evaluating synoptic controls on glacier meteorology and surface energetics; significant improvements in the parameterization of boundary-layer meteorology and ablation rates are realised through their application.
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Milrad, Shawn. "A climatology and synoptic-dynamic basis for distinguishing cool-season precipitation events at St. John's, Newfoundland." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86588.
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For St. John's, Newfoundland, at the confluence of several North American storm tracks, we identify synoptic-scale characteristics and precursors of various classes of cool-season precipitation events.Such events, based upon a climatology for 1979-2005, are separated into three categories based on precipitation amount. We find that the storm systems responsible for extreme precipitation events originate farther south and east than corresponding features in moderate and light events. A wind climatology shows that extreme precipitation events at St. John's are characterized almost exclusively by easterly surface and 925 hPa geostrophic winds, and that both the surface and 925 hPa geostrophic winds rotate clockwise with decreasing precipitation amount.
Focusing on extreme events, we utilize two methods of manual synoptic typing to further partition events. The first method uses backward air parcel trajectories to separate events by air parcel source region. One subset of events ("west") is characterized by strong upper-level dynamics and high precipitable water values in the central United States, which helps to produce a strong cyclone upon reaching the Atlantic Ocean; this is not seen for "west" events outside the extreme category. The second method of synoptic typing utilizes time series of three ascent-forcing quasi-geostrophic (QG) variables. While most events are characterized by a strong upstream sea-level cyclone originating from the Gulf of Mexico ("cyclone"), a subset are dominated by strong low-level frontogenesis, in the absence of a substantial upstream cyclone ("frontal").
Finally, a dynamic and thermodynamic analysis, and forecast model evaluation is completed for consecutive extreme events in December 2008, which produced over 125 mm of precipitation over six days. The first event is a "cyclone", and is marked by strong QG forcing for ascent in the presence of low static stability and high values of subtropical moisture. The second event is a "frontal" event, and is associated with a persistent quasi-stationary baroclinic zone in the presence of moderately stable air and large values of low-level frontogenesis, in the absence of substantial temperature and vorticity advection. These two events highlight rather disparate means by which an extreme precipitation event can occur at St. John's.
Pour St. John's, Terre-Neuve, à la confluence de plusieurs trajectoires de tempêtes nord-américaines, nous identifions des caractéristiques à l'échelle synoptique et des précurseurs d'une variété de type d'événements de précipitation de la saison froide.
Ces événements, basés sur une climatologie allant de 1979-2005, sont séparés en trois catégories basées sur la quantité de précipitation. Nous trouvons que les systèmes de tempêtes responsables des événements de précipitation extrêmes débutent plus au sud et à l'est que les événements correspondants avec précipitation modérée ou faible. Une climatologie des vents montre que les événements de précipitation extrêmes à St. John's sont caractérisés presque exclusivement par des vents de surface et géostrophique à 925 hPa provenant de l'est, et tournant dans le sens des aiguilles d'une montre avec une diminution de la quantité de précipitation.
En se concentrant sur les événements extrêmes, nous utilisons deux méthodes de classification synoptique manuelle pour séparer davantage les événements. La première méthode utilise une trajectoire renversée des parcelles d'air pour séparer les événements en fonction de leur région d'origine. Un sous-ensemble des événements ("ouest") est caractérisé par une forte dynamique dans les niveaux supérieurs et des valeurs d'eau précipitable élevées dans le centre des États-Unis, ce qui aide à produire un puissant cyclone lorsque l'océan Atlantique est atteint; ceci n'est pas observé pour les événements "ouest" en dehors de la catégorie des extrêmes. La seconde méthode utilise des séries temporelles de trois variables quasi-géostrophiques (QG) forçant l'ascension. Bien que la plupart des événements sont caractérisés par un puissant cyclone au niveau de la mer en amont qui origine du Golfe du Mexique ("cyclone"), un sous-ensemble est dominé par une forte frontogenèse dans les niveaux inférieurs, en l'absence substantielle de cyclone en amont ("frontal").
Finalement, une analyse dynamique et thermodynamique, ainsi qu'une évaluation de modèle de prévision est complétée pour des événements extrêmes consécutifs en décembre 2008, qui produisent plus de 125 mm de précipitation sur une période de six jours. Le premier événement est du type "cyclone", et est marqué par un puissant forçage QG d'ascension en présence de faible stabilité statique et de hautes valeurs d'humidité subtropicale. Le deuxième événement est de type "frontal", et est associé à une zone barocline persistante d'air modérément stable et de hautes valeurs de frontogenèse dans les niveaux inférieurs en absence d'advection de température et de vorticité substantielle. Ces deux événements mettent en valeur des manières plutôt différentes par lesquelles un événement de précipitation extrême peut se produire à St. John's.
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Sarhan, Naser M. J. "Low level jets in the Kingdom of Saudi Arabia : climatology, synoptic analyses and meso-scale modelling." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437634.
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Islam, Md Rafiqul. "A SYNOPTIC APPROACH TO THE SOUTH ASIAN MONSOON CLIMATE." Kent State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=kent159481021640872.
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Howard, Ian M. "A synoptic climatology of nocturnal rainfall events during May, June and July for northeast Kansas, 1950-2012." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16895.
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Master of ArtsDepartment of Geography
John Harrington, Jr
Nighttime rainfall has long been thought of as an important component to the central Great Plains hydroclimate during the wettest three-month period known as the “late spring -early summer precipitation maximum.” Research has suggested that nocturnal rainfall in the region results from a phenomenon known as the nocturnal Great Plains Low-Level Jet (GPLLJ). The jet, which originates in the Gulf of Mexico, transports moisture into the Great plains during the nighttime hours and often provides fuel for nighttime convection. The climatological characteristics of nighttime rainfall, as well the configuration of the low-level winds and the mechanisms behind its formation during this three-month wet period, however; are not well understood. Using hourly rainfall data from Topeka, KS, the nighttime rainfall characteristics are examined Topeka, KS and other Kansas stations for a 63-year period from 1950-2012 for May-July. Additionally, using the NCEP/NCAR Reanalysis data, the structure and configuration of the southerly wind phenomenon was analyzed based on its horizontal and vertical characteristics for nighttime rainfall events in May, June and July. A subsequent analysis also analyzed the larger synoptic-scale environment in place for six half-month periods from May to July. The results indicate that nighttime rainfall is a major contributor to the overall moisture budget in the Great Plains, contributing close to 50% of the overall rainfall total for the three-month period. The percentage of nighttime rainfall increases from west-east across the state, as well as temporally from May to July. The southerly winds are at their strongest during May events, tends to reach its peak at 850 mb at 6z (0000LST) near south-central Oklahoma, and forms as the result of both synoptic and thermal mechanisms. The synoptic mechanisms in place that generate the a southerly wind component change by month, leading to incredible variation in terms of its characteristics during nighttime rainfall events.
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Lee, Cameron C. "The Relationship of Large-Scale Atmospheric Circulation Patterns to Tornadoes and the Impacts of Climate Change." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1274371690.
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Jayet, D. F. "An examination of observed climatic trends/changes over Banks Peninsula and the surrounding plains area, and their synoptic climatology." Thesis, University of Canterbury. Department of Geography, 1986. http://hdl.handle.net/10092/3866.
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Rainfall and temperature data were collected over the study
area (approximately 50 sites ), using all existing climatic records, to
analyse observed climatic trends/changes since instrumental records
began. These trends, using multiple regression analysis, were then
compared to changes in synoptic flow patterns based on daily surface
charts for the 1929 to 1985 period. Results indicate that changes in
synoptic flow pattern have a very significant impact on rainfall and
temperature trends.
Observed rainfall trends tend to show cyclic trends or spells of
wet and dry periods. Comparison with the literature suggests that
some of the observed 10 year rainfall trends were related to the
sunspot cycle, such as the winter rainfall trend. However changes in
synoptic flow patterns appear to be the most important factor
influencing rainfall trends. Temperature trends show a much stronger
relationship with synoptic flow patterns than rainfall,particularly
for maximum temperature trends.
Wet periods over the study area are categorised by increased
cyclonic activity in combination with increased southerlies and or,
easterly circulations while dry periods are related to anticyclonic
conditions and increased westerly circulation. Southerly, and to a
lesser exent easterly circulations, have the most significant
influence on temperature trends with a negative impact.
The synoptic climatology of daily rainfall patterns over the
study area indicated that the dominant rain-bearing winds come from
the southerly quarter, especially southwesterly airflows. Higher
rainfall probability and significant daily rainfall totals occur under
cyclonic conditions in association with southerly to northeasterly
airflows while anticyclonic west to northerly airflows produce the
lower values.
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Serra, Yolande L., and Kerrie Geil. "Historical and Projected Eastern Pacific and Intra-Americas Sea TD-Wave Activity in a Selection of IPCC AR5 Models." AMER METEOROLOGICAL SOC, 2017. http://hdl.handle.net/10150/624034.
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The tracks of westward-propagating synoptic disturbances across the Intra-Americas Sea (IAS) and far-eastern Pacific, known as easterly waves or tropical depression (TD) waves, are an important feature of the region's climate. They are associated with heavy rainfall events, seed the majority of tropical cyclones, and contribute to the mean rainfall across the region. This study examines the ability of current climate models (CMIP5) to simulate TD-wave activity and associated environmental factors across the IAS and far-eastern Pacific as compared to reanalysis. Model projections for the future are then compared with the historical model experiment to investigate the southward shift in CMIP5 track density and the environmental factors that may contribute to it. While historical biases in TD-wave track-density patterns are well correlated with model biases in sea surface temperature and midlevel moisture, the projected southward shift of the TD track density by the end of the twenty-first century in CMIP5 models is best correlated with changes in deep wind shear and midlevel moisture. In addition, the genesis potential index is found to be a good indicator of both present and future regions of high TD-wave track density for the models in this region. This last result may be useful for understanding the more complex relationship between tropical cyclones and this index in models found in other studies.
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McNally, Louis K. "The Weather of 1785: An Interdisciplinary Approach to Meteorological Reconstruction Using Forensic Synoptic Analysis." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/McNallyLK2004.pdf.
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Van, Jaarsveld Pieter Paul. "The integrative nature of the synoptic weather map in relation to adolescent cognitive structures and the teaching of senior secondary meteorology-climatology." Thesis, Rhodes University, 1988. http://hdl.handle.net/10962/d1004377.
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A poorly consolidated concept base creates considerable difficulty amongst adolescents when it comes to the higher order task of analyzing complex, abstract and scientific weather phenomena as they appear on synoptic charts. The nature of the difficulties which they experience tends to encourage them to resort to the rote memorisation of concepts rather than understanding them. Kuhn (1962) avers that concepts, not enquiry methods, are at the core of rational thought. A well taught concept becomes a well developed mental construct which encourages understanding. It is the author's firm belief that in order for pupils to come to a thorough understanding of senior secondary meteorology - climatology and the synoptic chart, teaching of basic concepts should be graded and sequential. This thesis attempts to show the difficulties inherent in synoptic climatology. It relates these difficulties to adolescent cognitive development. Within this framework, the syllabus and past examinations of the Cape Education Department, and textbooks are examined. Teachers' views and pupils' understanding are gauged through the analyses of questionnaires and worksheets respectively. Conclusions are drawn and the problems which teachers and pupils encounter are addressed.
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Ballinger, Thomas J. "A Synoptic Climatological Assessment of the Relationship between Arctic Sea Ice Variability and Climate Anomalies over North America." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1428419284.
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Adams, Ryan. "Bomb Cyclones of the Western North Atlantic." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1509530111664557.
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Dean, John Robert. "Improving Summer Drought Prediction in the Apalachicola-Chattahoochee- Flint River Basin with Empirical Downscaling." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/geosciences_theses/12.
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The Georgia General Assembly, like many states, has enacted pre-defined, comprehensive, drought-mitigation apparatus, but they need rainfall outlooks. Global circulation models (GCMs) provide rainfall outlooks, but they are too spatially course for jurisdictional impact assessment. To wed these efforts, spatially averaged, time-smoothed, daily precipitation observations from the National Weather Service cooperative network are fitted to eight points of 700 mbar atmospheric data from the NCEP/NCAR Reanalysis Project for climate downscaling and drought prediction in the Apalachicola-Chattahoochee-Flint (ACF) river basin. The domain is regionalized with a factor analysis to create specialized models. All models complied well with mathematical assumptions, though the residuals were somewhat skewed and flattened. All models had an R-squared > 0.2. The models revealed map points to the south to be especially influential. A leave-one-out cross-validation showed the models to be unbiased with a percent error of < 20%. Atmospheric parameters are estimated for 2008–2011 with GCMs and empirical extrapolations. The transfer function was invoked on both these data sets for drought predictions. All models and data indicate drought especially for 2010 and especially in the south.
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Burgin, Laura Elizabeth. "The impacts of weather and climate change on the spread of bluetongue into the United Kingdom." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3208.
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A large epizootic of the vector-borne disease bluetongue occurred in northern Europe from 2006-2009, costing the economies of the infected countries several hundreds of millions of euros. During this time, the United Kingdom (UK) was exposed to the risk of bluetongue by windborne incursions of infected Culicoides biting midges from the northern coast of mainland Europe. The first outbreaks which occurred in the UK in 2007 were attributed to this cause. Although bluetongue virus (BTV) no longer appears to be circulating in northern Europe, it is widely suggested that it and other midge-borne diseases may emerge again in the future, particularly under a changing climate. Spread of BTV is strongly influenced by the weather and climate however limited use has been made of meteorologically based models to generate predictions of its spread to the UK. The extent to which windborne BTV spread can be modelled at timescales from days to decades ahead, to inform tactical and strategic decisions taken to limit its transmission, is therefore examined here. An early warning system has been developed to predict possible incursion events on a daily timescale, based on an atmospheric dispersion model adapted to incorporate flight characteristics of the Culicoides vectors. The system’s warning of the first UK outbreak in September 2007 was found to be greatly beneficial to the UK livestock industry. The dispersion model is also shown to be a useful post-outbreak epidemiological analysis tool. A novel approach has been developed to predict BTV spread into the UK on climate-change timescales as dispersion modelling is not practical over extended periods of time. Using a combination of principal component and cluster analyses the synoptic scale atmospheric circulations which control when local weather conditions are suitable for midge incursions were determined. Changes in the frequency and timing of these large scale circulations over the period 2000 to 2050 were then examined using an ensemble of regional climate model simulations. The results suggest areas of UK under the influence of easterly winds may face a slight increase in risk and the length of the season where temperatures are suitable for BTV replication is likely to increase by around 20 days by 2050. However a high level of uncertainty is associated with these predictions so a flexible decision making approach should be adopted to accommodate better information as it becomes available in the future.
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Lee, Cameron C. "The Development of a Gridded Weather Typing Classification Scheme." Thesis, Kent State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618946.
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Since their development in the 1990s, gridded reanalysis data sets have proven quite useful for a broad range of synoptic climatological analyses, especially those utilizing a map pattern classification approach. However, their use in broad-scale, surface weather typing classifications and applications have not yet been explored. This research details the development of such a gridded weather typing classification (GWTC) scheme using North American Regional Reanalysis data for 1979-2010 for the continental United States.
Utilizing eight-times daily observations of temperature, dew point, pressure, cloud cover, u-wind and v-wind components, the GWTC categorizes the daily surface weather of 2,070 locations into one of 11 discrete weather types, nine core types and two transitional types, that remain consistent throughout the domain. Due to the use of an automated deseasonalized z-score initial typing procedure, the character of each type is both geographically and seasonally relative, allowing each core weather type to occur at every location, at any time of the year. Diagnostic statistics reveal a high degree of spatial cohesion among the weather types classified at neighboring locations, along with an effective partitioning of the climate variability of individual locations (via a Variability Skill Score metric) into these 11 weather types. Daily maps of the spatial distribution of GWTC weather types across the United States correspond well to traditional surface weather maps, and comparisons of the GWTC with the Spatial Synoptic Classification are also favorable.
While the potential future utility of the classification is expected to be primarily for the resultant calendars of daily weather types at specific locations, the automation of the methodology allows the classification to be easily repeatable, and therefore, easily transportable to other locations, atmospheric levels, and data sets (including output from gridded general circulation models). Further, the enhanced spatial resolution of the GWTC may also allow for new applications of surface weather typing classifications in mountainous and rural areas not well represented by airport weather stations.
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Bari, Driss. "Etude du brouillard en zone côtière par modélisation des processus physiques de la couche limite atmosphérique : cas du Grand Casablanca (Maroc)." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30316/document.
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Le brouillard est un phénomène météorologique très difficile à prévoir, même à très courte échéance, en raison de sa grande variabilité spatiale et temporelle qui est due à des interactions complexes entre divers processus physiques. Dans cette thèse, les caractéristiques météorologiques locales et les processus synoptiques favorables aux brouillards sur la région du Grand Casablanca (Maroc) sont examinés à l'aide des observations horaires aux deux stations météorologiques permanentes de cette région côtière. Un algorithme de classification objectif est développé et utilisé pour classer les événements en des types de brouillard les plus rencontrés. Cette étude climatologique a mis en évidence que le brouillard a le plus souvent un caractère localisé et que le type d'advection-rayonnement est le plus fréquent sur la région, suivi des types d'affaissement de stratus et de rayonnement. Quand le brouillard intéresse simultanément les deux stations, la probabilité d'observer deux types différents est assez élevée. Les processus advectifs liés à la circulation de brise de mer au cours de l'après-midi, suivis de ceux radiatifs en début de nuit jouent un rôle important dans la formation du brouillard sur la région. Des simulations numériques à l'aide du modèle Méso-NH sont réalisées. Ces simulations ont confirmé que les processus physiques impliqués dans le cycle de vie du brouillard peuvent être différents selon la nature géographique de la surface. Elles ont aussi mis en évidence que la prévision numérique du brouillard en zone côtière est sensible à la température de la surface de la mer, à la topographie locale, et à l'occupation du sol. De plus, la prévision du brouillard côtier dépend fortement de la capacité du modèle à reproduire correctement la circulation de brise au cours de l'après-midi et les processus radiatifs en début de nuit. Les simulations systématiques des cas de brouillard de l'hiver 2013-2014 a montré la capacité du modèle Méso- NH à reproduire l'occurrence du brouillard avec néanmoins un taux relativement élevé de fausses alarmes, en particulier à la station côtièreThe prediction of fog remains a challenge due to its time and space variability and to the complex interaction between the numerous physical processes influencing its life cycle. During the first stage of this thesis, the local meteorological and synoptic characteristics of fog occurrence over the Grand Casablanca region (Morocco) are investigated. To achieve this, hourly surface meteorological observations, at two synoptic stations of this coastal region, are used. An objective fog-type classification has been developed in this work and used to discriminate the fog events into the well known types. This fog climatology points out that the fog is often localized and that it is predominantly of advection-radiation type, followed by fog resulting from cloud base lowering and radiation fog. Besides, two different fog types can occur when fog simultaneously concerns the two stations. The advective processes associated with sea breeze circulation during the daylight, followed by the radiative processes often leads to fog formation over this coastal region. Numerical simulations are performed later using the meso-scale non-hydrostatic model Meso-NH. These simulations confirm that the physical processes, governing the life cycle of fog, can be different according to the physiographic features of the area. Moreover, the numerical prediction of coastal fog over heterogeneous area is very sensitive to sea surface temperature, land local topography and land cover. It also depends on the model's ability to reproduce the sea breeze circulation during the daylight followed by the radiative processes early in the night. The systematic numerical simulations of the fog events that occurred during the winter 2013-2014 indicate the Meso-NH's ability to well capture the fog occurrence with a relatively high false alarm rate, particularly over the coastal station
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Zuluaga-Arias, Manuel D. "Spatio-temporal variability of aerosols in the tropics relationship with atmospheric and oceanic environments." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41202.
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Earth's radiation budget is directly influenced by aerosols through the absorption of solar radiation and subsequent heating of the atmosphere. Aerosols modulate the hydrological cycle indirectly by modifying cloud properties, precipitation and ocean heat storage. In addition, polluting aerosols impose health risks in local, regional and global scales.
In spite of recent advances in the study of aerosols variability, uncertainty in their spatial and temporal distributions still presents a challenge in the understanding of climate variability. For example, aerosol loading varies not only from year to year but also on higher frequency intraseasonal time scales producing strong variability on local and regional scales. An assessment of the impact of aerosol variability requires long period measurements of aerosols at both regional and global scales.
The present dissertation compiles a large database of remotely sensed aerosol loading in order to analyze its spatio-temporal variability, and how this load interacts with different variables that characterize the dynamic and thermodynamic states of the environment. Aerosol Index (AI) and Aerosol Optical Depth (AOD) were used as measures of the atmospheric aerosol load. In addition, atmospheric and oceanic satellite observations, and reanalysis datasets is used in the analysis to investigate aerosol-environment interactions. A diagnostic study is conducted to produce global and regional aerosol satellite climatologies, and to analyze and compare the validity of aerosol retrievals. We find similarities and differences between the aerosol distributions over various regions of the globe when comparing the different satellite retrievals. A nonparametric approach is also used to examine the spatial distribution of the recent trends in aerosol concentration. A significant positive trend was found over the Middle East, Arabian Sea and South Asian regions strongly influenced by increases in dust events.
Spectral and composite analyses of surface temperature, atmospheric wind, geopotential height, outgoing longwave radiation, water vapor and precipitation together with the climatology of aerosols provide insight on how the variables interact. Different modes of variability, especially in intraseasonal time scales appear as strong modulators of the aerosol distribution. In particular, we investigate how two modes of variability related to the westward propagating synoptic African Easterly Waves of the Tropical Atlantic Ocean affect the horizontal and vertical structure of the environment. The statistical significance of these two modes is tested with the use of two different spectral techniques. The pattern of propagation of aerosol load shows good correspondence with the progression of the atmospheric and oceanic synoptic conditions suitable for dust mobilization over the Atlantic Ocean. We present extensions to previous studies related with dust variability over the Atlantic region by evaluating the performance of the long period satellite aerosol retrievals in determining modes of aerosol variability. Results of the covariability between aerosols-environment motivate the use of statistical regression models to test the significance of the forecasting skill of daily AOD time series. The regression models are calibrated using atmospheric variables as predictors from the reanalysis variables. The results show poor forecasting skill with significant error growing after the 3rd day of the prediction. It is hypothesized that the simplicity of linear models results in an inability to provide a useful forecast.
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Kirk, Johnathan. "Hydroclimatic Variability and Contributing Mechanisms during the Early 21st Century Drought in the Colorado River Basin." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1500480359156882.
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Smith, Erik T. "The Characteristics of Cold Air Outbreaks in the eastern United States and the influence of Atmospheric Circulation Patterns." Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1499870942487366.
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Foss, Marilei. "CONDIÇÕES ATMOSFÉRICAS CONDUCENTES À OCORRÊNCIA DE TEMPESTADES CONVECTIVAS SEVERAS NA AMÉRICA DO SUL." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/10256.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorAn investigation of the atmospheric environments prone to severe convective weather is conducted for the subtropics of South America, east of the Andes Mountain Range. Upper air soundings valid at 00Z and 12Z for six sounding sites in subtropical South America (namely, Porto Alegre/BRA, Florianópolis/BRA, Curitiba/BRA, Foz do Iguaçu/BRA, Resistência/ARG e Buenos Aires/ARG) are employed to generate a short 12-yr climatology (from January 1998 to December 2009) of some of the main necessary ingredients for severe thunderstorm development: moisture availability, conditional instability, and vertical wind shear (VWS). The goal of the climatology is to document the typical magnitudes and seasonal variability of those ingredients with the aid of convective parameters. Threshold magnitudes for such parameters were objectively determined (via quantile analysis) and tested as cut-off criteria utilized to discriminate the severe weather environments. To that end, classic North-American threshold values extracted from the literature were also tested and the results compared vis-à-vis the South-American counterparts. Distinct combinations of such thresholds were employed to select atmospheric profiles theoretically conducive to severe thunderstorms and tornadoes. Atmospheric profiles obtained from the NCEP-NCAR Reanalysis data valid at 18Z were also used. The time and space distribution of the selected severe weather profiles were examined, emphasizing the seasonal variation and geographic distribution. From these sampled profiles, composite analysis were built for and Principal Component Analysis were applied to relevant meteorological variables at distinct vertical levels in order to search for the associated synoptic-scale patterns. The climatology succesfully reproduced the expected seasonal behavior of parameters that are indicative of conditional instability and VWS. Compared to the North-American climatology, the magnitudes found for the 700-500hPa lapse rates, 0-6km bulk shear and height of the LCL were lower in South America. The seasonal variability and space distribution of the severe weather profiles suggest that there exists an equatorward [poleward] displacement of the severe weather activity as winter [summer] approaches. The synoptic pattterns associated with the severe weather environments is different from those traditionally recognized for North America, particularly at the surface.
Neste trabalho é realizada uma investigação dos ambientes favoráveis ao desenvolvimento de convecção severa nos subtrópicos da América do Sul (AS) à leste dos Andes. Sondagens de ar superior das 00Z e 12Z de seis estações distribuídas na região subtropical da AS (quais sejam: Porto Alegre/BRA, Florianópolis/BRA, Curitiba/BRA, Foz do Iguaçu/BRA, Resistência/ARG e Buenos Aires/ARG), foram utilizadas para gerar uma pequena climatologia (12 anos; de janeiro de 1998 a dezembro de 2009) de alguns dos principais ingredientes necessários para o desenvolvimento de convecção severa: oferta de umidade, instabilidade condicional termodinâmica e cisalhamento vertical do vento (CVV). A climatologia visou documentar as magnitudes típicas e a variação sazonal destes parâmetros para a região de interesse. Valores significativos dos parâmetros foram objetivamente identificados via análise de quantis e testados como limiares combinados para salientar ambientes favoráveis ao desenvolvimento de tempestades severas. Limiares para a América do Norte documentados na literatura também foram testados para este fim e confrontados com os respectivos valores da amostragem sul-americana. Diferentes combinações destes limiares foram empregadas para se extrair os perfis atmosféricos considerados teoricamente favoráveis a tempestades severas e tornados. Perfis de tempo severo também foram extraídos dos dados da Reanálise do NCEP-NCAR válidos às 18Z. Foi examinada a distribuição temporal e espacial destes ambientes de tempo severo explorando sua sazonalidade e distribuição geográfica. Partindo destes perfis, foram analisados os padrões sinóticos predominantes na região através da composição média e Análise de Componentes Principais para as variáveis meteorológicas mais relevantes em diferentes níveis verticais. A climatologia reproduziu bem o comportamento sazonal esperado dos parâmetros de instabilidade termodinâmica e CVV. Em comparação com a climatologia da América do Norte encontrou-se para a América do Sul valores mais baixos de lapse rates na média troposfera, CVV na camada entre 0-6km, e altura do NCL. A distribuição sazonal e espacial dos perfis de tempo severo sugere uma migração geográfica das condições de tempo severo das latitudes mais baixas [altas] para as latitudes mais altas [baixas] à medida que nos aproximamos dos meses de verão [inverno]. O padrão sinótico de tempo severo na América do Sul é diferente daquele tradicionalmente documentado para a América do Norte, especialmente em superfície.
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Kline, Wayne T. "Climatic Factors Associated with the Rapid Wintertime Increase in Cloud Cover across the Great Lakes Region." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1240256371.
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Cheng, Chu-Chai. "A 15-year climatology of synoptical disturbance over tropical northwestern Pacific during summer." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA294767.
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Esteban, Vea Pere. "Classificació de tipus de circulació atmosfèrica: proposta metodològica i aplicacions." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/93320.
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La classificació de la circulació atmosfèrica s’ha abordat de diferents maneres: mètodes manuals, mixtes, basats en l’estadística multivariant, entre d’altres. En aquest treball es fa un extens i actualitzat recorregut per aquests mètodes i es fa una proposta metodològica basada en l’anàlisi per components principals: el mètode de les puntuacions extremes. Aquesta metodologia, basada en l’aproximació tradicional que empra la matriu tipus S, proposa una estandardització espacial de les dades originals (malles), l’ús dels valors més elevats de les puntuacions factorials per a la determinació del nombre de grups de la classificació i els seus centroides, i finalment l’assignació dels casos a algun dels grups sense l’ús de les iteracions característiques dels mètodes de k-mitjanes.
La proposta s’aplica posteriorment a diferents casos pràctics relacionats amb diferents enfocs de les ciències atmosfèriques: meteorologia de muntanya, variabilitat climàtica i canvi climàtic, cartografia climàtica i riscos meteorològics. Aquests casos pràctics es presenten a través de quatre articles publicats a diferents revistes internacionals.
El primer cas fa una caracterització de les nevades intenses al Principat d’Andorra a partir de la classificació de la pressió en superfície a l’àmbit de l’Europa Occidental, obtenint-se set patrons de circulació que expliquen la varietat de situacions associades a nevades superiors a 30cm en 24 hores en algun lloc del Principat. La detecció d’aquesta variabilitat, i la detecció de situacions de la mateixa component però amb diferencies en el gradient de pressió fan del catàleg obtingut com una eina interessant en la predicció meteorològica en aquest sector del Pirineu. Aquest article va ser publicat a la revista International Journal of Climatology l’any 2005.
El segon cas fa una classificació genèrica de la circulació atmosfèrica a l’Europa Occidental, entre 1960 i 2001 i emprant, com en el cas anterior, el reanàlisi de l’NCEP-NCAR (1 dada diària i 2.5º de resolució espacial). S’obtenen 20 patrons que expliquen de forma molt completa la variabilitat de la circulació atmosfèrica en aquest sector. A més, per cadascun dels patrons obtinguts s’ha calculat la seva distribució anual i la seva tendència al llarg del període. Precisament sobre aquest darrer punt, alguns patrons mostren tendències estadísticament significatives que apunten cap a un increment de les situacions de bloqueig anticiclònic durant les dècades estudiades. L’article fou publicat a International Journal of Climatology al 2006.
El tercer cas aborda la obtenció de cartografia de temperatura i precipitació en zones d’orografia complexa (Andorra) relacionada amb els patrons de circulació obtinguts en el treball anterior. Els resultats, 80 mapes d’alta resolució calculats amb el mètode de la regressió múltiple, mostren la variabilitat climàtica local basada en la discriminació que estableix un catàleg de la circulació atmosfèrica. L’article fou publicat a la revista Theoretical and Applied Climatology al 2009.
Finalment, el quart cas aborda l’activitat dels llamps al sector d’Andorra i Catalunya, però en aquest cas classificant una malla de pressió en superfície de més resolució temporal i espacial (dades cada 6 hores i a 1º). S’obtenen nou tipus de circulació atmosfèrica que representen situacions de caràcter advectiu (definides sobretot pel context sinòptic), dominades per la dinàmica mesoescalar (normalment efecte del dipol orogràfic pirinenc), o situacions de caràcter tèrmic dominades per la manca de gradient bàric. Aquest treball fou publicat a Physics and Chemistry of the Earth al 2010.
Els resultats mostren que la proposta del mètode de les puntuacions extremes és una opció prou robusta per a la obtenció de tipus de circulació atmosfèrica i que pot ser aplicada a diferents resolucions temporals i espacials. Aquest mètode ha estat implementat al programari lliure COST733class desenvolupat en l’àmbit del projecte europeu COST733 (2005-2010) centrat en la comparació i avaluació de mètodes de classificació de la circulació atmosfèrica.Atmospheric circulation types classification: a method proposal and applications The classification of atmospheric circulation has been addressed via different methodological approaches: manual methods, mixed methods, based on multivariate techniques, etc. In this work we present an extensive overview of the main existing typologies of circulation type classification methods for finally propose a new approach based on principal component analysis: the method of extreme scores. This new approach highlight the spatial standardization of the original data (gridded data), the use of the factor scores for determining the total amount of circulation types and their centroids, and finally support the non use of iterations for the final classification of all the cases into the groups via the Euclidian distance. The proposal is then applied to heavy snow precipitation events in Andorra (Pyrenees), to climate variability analysis over Western Europe, to the interpolation of climate variables in mountain areas (temperature and precipitation in Andorra) based on circulation types, and for analyze relevant lightning activity over the sector of Catalonia and Andorra. These applications are presented trough the corresponding publications in international scientific journals, and exemplify the usefulness of the atmospheric circulation classification methods for the study of mountain meteorology, climate variability and climate change, climate mapping in areas of complex topography using GIS techniques, and weather hazards situations. In addition, these applications also demonstrate the goodness of the proposed method of the extreme scores. This method of the extreme scores has been included in the classification software COST733class developed by the European project COST733 that was focused on the comparison and evaluation of circulation type classification methods.
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Blair, Danny Ernest. "The synoptic climatology of the Red River Region." 2009. http://hdl.handle.net/1993/3531.
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This thesis develops a synoptic climatology for the Red River Region (RRR) of southern Manitoba, North Dakota, South Dakota, and Minnesota. The Sums-of-Squares technique is used to objectively classify each of the days of 1946-84 according to the type of pressure pattern observed 1) at the 500 mb level over much of North America west of the Great Lakes, 2) at the 500 mb level over a smaller area of west-central North America, and 3 ) at mean-sea level (MSL) over the same small area. Eighteen large-area 500 mb, 20 small-area 500 mb, and 29 MSL patterns are used to represent the most common synoptic situations. The characteristics of these representative patterns are described, and their average monthly frequencies used to determine natural 500 mb and MSL pressure pattern seasons. Four 500 mb and four MSL seasons are identified. Winter and summer 500 mb regimes are found to be most dissimilar, with winter dominated by many large troughs pulling northern air into the central part of North America, including the RRR, and summer dominated by zonal and ridge-associated patterns. The winter MSL regime shows more highs north of the RRR than does the summer, and fall exhibits more lows toward the north. Spring and fall are transitional months at both pressure levels. Results are discussed in relation to the seasonal migration of the polar front. The average weather characteristics associated with the synoptic types at Winnipeg, Manitoba, and Fargo, North Dakota, are calculated and compared. Temperature conditions are assessed by calculating mean departures from mean daily temperatures and precipitation characteristics are evaluated by calculating precipitation efficiencies, or amounts of total precipitation produced relative to frequency of occurrence. Temperatures in the RRR are found to be strongly correrated to wind direction, and precipitation potential related to apparent vertical motions in the atmosphere. Finally, discriminant analysis and the MSL classification is used to identify the surface pressure patterns whose frequencies in the six months immediately preceding April are significantly different in years with low and high Red River flows, in April, at Emerson, Manitoba. The weather normally produced by the patterns selected as good predictor variables is discussed in relation to the hydrometeorological conditions known to be conducive to extreme Red River flows.
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LaDochy, Stephen. "The synoptic climatology of severe thunderstorms in Manitoba." 1985. http://hdl.handle.net/1993/29881.
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Harrison, Michael Stanley John. "A synoptic climatology of South African rainfall variations." Thesis, 2015. http://hdl.handle.net/10539/16735.
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Rauscher, Sara A. "Synoptic climatology of the northern hemisphere during the Medieval Warm Period." 1994. http://catalog.hathitrust.org/api/volumes/oclc/32486673.html.
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Grauman, Rhett D. "Rapid cyclolysis in the North Pacific Ocean synoptic-climatology and a diagnostic case study /." 1999. http://catalog.hathitrust.org/api/volumes/oclc/42195001.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1999.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 137-140).
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Alghamdi, Ali Saeed Arifi. "Climatology of warm season heat waves in Saudi Arabia: a time-sensitive approach." Diss., 2018. http://hdl.handle.net/2097/39035.
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Doctor of PhilosophyDepartment of Geography
John A. Harrington Jr
The climate of the Middle East is warming and extreme hot temperature events are becoming more common, as observed by the significant upward trends in mean and extreme temperatures during the last few decades. Climate modeling studies suggest that the frequency, intensity, and duration of extreme temperature events are expected to increase as the global and local climate continues to warm. Existing literature about heat waves (HWs) in Saudi Arabia provides information about HW duration using a single index, without considering the observed effects of climate change and the subtropical arid climate. With that in mind, this dissertation provides a series of three stand-alone papers evaluating temporal, geographic, and atmospheric aspects of the character of warm season (May-September) HWs in Saudi Arabia for 1985 to 2014. Chapter 2 examines the temporal behavior(s) of the frequency, duration, and intensity of HWs under the observed recent climate change. Several issues are addressed including the identification of some improved methodological practices for HW indices. A time-sensitive approach to define and detect HWs is proposed and assessed. HW events and their duration are considered as count data; thus, different Poisson models were used for trend detection. Chapter 3 addresses the spatio-temporal patterns of the frequency and intensity of hot days and nights, and HWs. The chapter reemphasizes the importance of considering the on-goings effects of climate warming and applies a novel time-series clustering approach to recognize hot temperature event behavior through time and space. Chapter 4 explores the atmospheric circulation conditions that are associated with warm season HW event occurrence and how different HWs aspects are related to different circulation types. Further, possible teleconnections between HWs and sea surface temperature (SST) anomalies of nearby large bodies are examined. Results from Chapters 2 and 3 detected systematic upward trends in maximum and minimum temperatures at most of the 25 stations, suggesting an on-going change in the climatology of the upper-tail of the frequency distribution. The analysis demonstrated the value of using a time-sensitive approach in studying extreme thermal events. Different patterns were observed over time and space not only across stations but also among extreme temperature events (i.e., hot days and nights, and HWs). The overall results suggest that not only local and regional factors, such as elevation, latitude, land cover, atmospheric humidity, and distance from a large body of water, but also large-scale factors such as atmospheric circulation patterns are responsible for the observed temporal and spatial patterns. Chapter 4 confirmed that as the Indian Summer Monsoon Trough and the Arabian heat low were key atmospheric features related to HW days. SST anomalies seemed to be a more important factor for HWs intensity. Extreme thermal events in Saudi Arabia tended to occur during regional warming due to atmospheric circulation conditions and SSTs teleconnections. This study documents the value of a time-sensitive approach and should initiate further research as some of temporal and spatial variabilities were not fully explained
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Thomas, Blaine Conrad. "The Alberta Clipper a synoptic climatology, composite life cycle analysis, and survey of its relationship to large-scale features /." 2004. http://catalog.hathitrust.org/api/volumes/oclc/56838000.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 2004.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 140-147).
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Sýkorová, Petra. "Zpracování klimatologických měření z experimentálních lokalit v Kyrgyzstánu a jejich synopticko-klimatologická interpretace." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-347654.
Full textAbstract:
The Charles University Faculty of Science KFGG team took part in an intensive research in the area of Kyrgyz glacial lakes. The collecting of records from three meteorological stations in the locations of Kolor (2,700 m above sea level) and Adygine (3,500 and 3,800 meters above sea level) was part of the research. The aim of this thesis was to analyze the homogeneity of climatic data measured in experimental locations using the SNHT method (Standard Normal Homogeneity Test), process the data using general climatological processes, create a classification of circulation types for the area of interest using Jenkinson's and Collinson's method, and finally, to quantify the relationships between individual circulation types and the values of chosen climatic elements. The analysis results are homogenized climatic sets for the Adygine H station (3,800 m above sea level) and a summary of basic statistics and trends of climatic elements in the area. Furthermore, a catalogue of circulation types was created for the period from August 2007 to July 2011, and finally, the relationships between individual circulation types and manifestations of climate elements (air temperature, precipitation and global radiation). The results of this thesis may be used to identify the types connected with bursts of glacial...