Made available in DSpace on 2014-06-11T19:31:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-07Bitstream added on 2014-06-13T20:42:06Z : No. of bitstreams: 1 silva_es_dr_botfca.pdf: 10346653 bytes, checksum: 0b5ebb401c7fae9a321556854e1199cf (MD5) / Universidade Estadual Paulista (UNESP) / Pqi / O objetivo deste trabalho foi analisar as variabilidades espacial, sazonal e interanual da precipitação pluviométrica nas regiões Sudeste e Sul do Brasil. Foram utilizadas 164 séries mensais e anuais de chuvas para o período de 1972 a 2002 e dados de médias mensais de radiação de ondas longas emergentes (ROLE), para o período de junho de 1974 a dezembro de 2002, com pontos de grade com resolução espacial de 2,5º x 2,5º, entre as latitudes 20ºN e 35ºS e longitudes entre 0º; 90ºW. A partir das análises de agrupamento, de componentes principais e geoestatística foram identificadas 13 regiões homogêneas de regime de precipitação. A precipitação anual variou de 956 mm nos vales do São Francisco- Jequitinhonha a 1830 mm na Bacia do Iguaçu-Chapecó. As três primeiras componentes principais (CP) da matriz de médias mensais de precipitação explicam conjuntamente, 61,49% da variância. A primeira CP representa o campo médio de precipitação, a segunda CP representa o período de verão e a terceira CP apresenta dois pontos extremos: o mês de novembro e o mês de fevereiro. Através dos dados de ROLE analisou-se a influência da Zona de Convergência do Atlântico Sul (ZCAS) na precipitação. As três primeiras componentes principais da matriz de médias mensais de ROLE explicam conjuntamente 96,27% da variância. A primeira CP representa a convecção média. A segunda CP representa o período de primavera e a terceira CP representa o período de verão. As correlações, significativas ao nível de 5%, obtidas entre os autovetores das matrizes de precipitação pluviométrica e de ROLE, corroboram a influência da ZCAS no regime de precipitação das regiões Sudeste e Sul do Brasil. / The spatial, seasonal and interannual variability of rainfall in Southeastern and Southern Brazil were analyzed. For that, 164 series of rainfall for the period of 1972 to 2002 and data about outgoing longwave radiation (OLR) for the period of 1974 to 2002 were utilized. From the clusters analysis and components analysis (PCA), 13 homogeneous regions under precipitation regime were identified. The annual rainfall varied from 956 mm in São Francisco-Jequitinhonha valleys to 1830 mm in Iguaçu-Chapecó basin. The three first matrix principal components (PC) of monthly average rainfall (average of 30 years) explain together 61.49% of the variance. The first PC represents the mean rainfall field, the second PC represents the extended rainy period (September to May) and the third PC presents two extreme points: November indicates the end of spring and the beginning of summer; and February indicates the end of summer and the beginning of autumn. The OLR influence on the rainfall variability in the Southeast and in the South was also evaluated. Through the PCA, the behavior of the South Atlantic Convergence Zone (SACZ) was studied together with its influence on the rainfall variability. The three first matrix main components of OLR monthly average (average of 30 years) explain together 96.27% of the variance. The first main component (CP) is associated to the period of autumn. The second PC represents the winter/summer period, and the third PC represents summertime. The correlations, significative to the level of 5%, obtained between the rainfall and OLR eigenvectors, attest their influence on the rainfall regime in Southeastern and Southern Brazil.

Spatial and temporal distribution of precipitation in the Vosges mountain range area Abstract The aim of this work is to study the climatology of atmospheric precipitation in the studied area situated in the Northeastern France. Factors, e.g. the global circulation of the atmosphere, that influence the spatial and temporal distribution of precipitation in the mid-latitudes, especially in Western Europe and in mountainous regions, are discussed from the macro- to micro- scale in the first part. The term "ombric continentality" is clarified and a description of the physical geography of the studied area is performed, e.g. upward and windward asymmetry of Vosges slopes and contrasts between the mountain range and the Upper Rhine Plain. Secondly a demonstration is made that the Vosges mountain range affects, due to its position, the spatio-temporal distribution of precipitation at a regional scale. This is carried out by computing the daily rainfall on 14 meteorological stations out of the period 1951-2011. Three categories of stations were determined according to their annual precipitation repartition: (i) mountain stations with the winter precipitation maximum, (ii) leeward slope stations with two precipitation maxima, i.e. in winter and summer and (iii) leeward stations located in the Upper Rhine Plain East...

Anthropogenic climate change risks significant changes in the global distribution of precipitation. Across the western United States, modelling studies show significant reductions in wetness that imply weighty societal and ecological impacts. But the validity of the model projections need to be ground-truthed. Paleo-hydroclimate data are useful reference points to assess a model’s ability to hindcast past hydroclimate. If the hindcast matches the paleodata, it brings confidence to a model’s ability to predict future hydroclimatic change. The foremost metric of hydroclimate in the geologic record is the surface area of lakes in hydrologically closed basins. In such basins, a lake’s surface area is determined by the balance between precipitation and evaporation. The lake will expand when the balance is positive, and it will contract when the balance is negative. In this dissertation, I develop a 25-9 ka record of lake fluctuation from the Mono Basin, a hydrologically closed basin in east-central California. I deduced the fluctuations using three pieces of evidence: stratigraphy; geomorphology; and geochronology. These pieces of evidence were determined from a study of the Mono Basin’s Late Pleistocene lithostratigraphic unit: the Wilson Creek Formation. There are 19 tephra intercalated in the Wilson Creek tephra. They are named by their reverse depositional order (Ash 19 is the oldest and Ash 1 is the youngest). Uncertainty on their ages cause confusion as to the paleo-hydroclimate record of the Mono Basin. The age of Ash 19, for example, is important because its deposition marks the onset of relatively high lake levels that occurred during the last glaciation. There are two principal interpretations of Ash 19’s age: 40 ka, which is based on lacustrine macrofossil 14C data; and 66 ka, which is underpinned by paleomagnetic intensity data. In chapter 2, I tested these end-member interpretations. I used the U/Th method to date carbonate deposits that underlie and cut across Ash 19. The U/Th data show that Ash 19 must have been deposited between these two dates: 66.8 ± 2.8 ka; and 65.4 ± 0.3 ka. These dates are, therefore, more consistent with the 66 ka interpretation of Ash 19’s age. Thus the onset of relatively high lake levels in the Mono Basin corresponds with the rapid drawdown of atmospheric CO2 during Marine Isotope Stage 4. The coincidence between the drop in atmospheric CO2 and lake level rise is suggestive of a causal link. In chapter 3, I determined Mono Lake's fluctuations 25-9 ka. This time encompasses three climatic intervals: the coolest time of the last glaciation, termed the Last Glacial Maximum (LGM); the period corresponding to the rapid termination of the last glaciation, termed the deglaciation; and the early Holocene, a period of inordinate warmth that immediately followed the last glaciation’s termination. In this study, I used stratigraphic and geomorphic evidence in conjunction with 14C and U/Th dates. I measured the 14C dates on bird bones and charcoal. And I measured the U/Th dates on carbonates. Together the data showed that the lake's rises and falls concurred with North Atlantic climate. Periods of aberrant warmth in the North Atlantic concurred with low stands of Mono Lake. On the other hand, extreme cooling in the North Atlantic correlated with Mono Lake high stands. The timing of these lake fluctuations also corresponds with variations in other tropical and mid-latitude hydroclimatic records. The global harmony in the hydroclimatic records suggests a unifying conductor. I hypothesize that the conductor is tropical atmospheric circulation. In chapter 4, I present evidence on the peculiar case of an extreme low stand of Mono Lake. The low stand is dubbed the “Big Low”. The principal evidence underpinning the Big Low derives from a sedimentary sequence exposed along the canyon walls of Mill Creek. The strata show that the lake fell below 1,982 m between the deposition of Ashes 5 and 4—making this low stand the lowest recognized level of Mono Lake during the Wilson Creek Formation. Observations from dispersed sequences corroborate this interpretation. And three data constrain the age of the Big Low to be between ~24.4-20.5 ka: a carbonate U/Th date on a littoral conglomerate associated with the Big Low; a carbonate U/Th date that underlies Ash 4; and a carbonate U/Th date that cuts across Ash 5. Thus the interval that the Big Low must occur within encompasses the LGM. The timing of this low stand, therefore, corresponds with summer temperature minima, suggesting that the fall was due not to an increase in evaporation but due to a decrease in precipitation. This finding is counter to conventional wisdom: that the LGM was a relatively wet interval. In addition, both the documentation of a low stand during glacial maximum conditions and the inference that precipitation must have been reduced are contrary to previous published interpretations from model and paleoclimatic data. These discrepancies raise significant questions about our understanding of the regional expression and forcing of hydroclimate across the western United States during the LGM. Because of this period’s importance to ground-truthing climatic models, additional evidence on the geographic extent of this unexpected result is essential.

Novel seasonal hidden Markov models (SHMMs) for stochastic time series with periodically varying characteristics are developed. Nonlinear interactions among SHMM parameters prevent the use of the forward-backward algorithms which are usually used to fit hidden Markov models to a data sequence. Instead, Powell's direction set method for optimizing a function is repeatedly applied to adjust SHMM parameters to fit a data sequence. SHMMs are applied to a set of meteorological data consisting of 9 years of daily rain gauge readings from four sites. The fitted models capture both the annual patterns and the short term persistence of rainfall patterns across the four sites.

Precipitation is one of the atmospheric variables that characterize the climate of a region. The South Island of New Zealand (SI of NZ) has an unusually large number of distinct regional climates and its climatic diversity includes the coldest, wettest, driest and windiest places in New Zealand. This thesis focuses on identifying precipitation trends and rainfall fluctuations for the SI of NZ. First, homogeneity of 184 precipitation series is assessed with the combination of three homogeneity tests (Standard Normal Homogeneity Test, Easterling & Peterson test, Vincent�s Multiple Linear Regression). More than 60% of tested time series are found to contain at least one inhomogeneity. About 50% of the inhomogeneities can be traced to information in the station history files with nearly 25% of all inhomogeneities caused by the relocation of the precipitation gauge. Five coherent precipitation regions are defined by the Principal Component Analysis. The objective of identifying the periods of water deficit and surplus in spatial and temporal domains is achieved by using Standardized Precipitation Index (SPI). The SPI series (for 3, 6, 12, 24 and 48 months time scales) are calculated for each region and used for analysis of dry and wet periods. Clear differences in the frequency, length and intensity of droughts and wet periods were found between individual regions. There is a positive (i.e. increase in wet periods) trend in SPI time series for the North, Westland and Southland regions during the 1921-2003 period at all times scales, and a negative trend for Canterbury during the same period. The results show longer wet periods than dry periods at all time scales. Extreme heavy precipitation, which causes floods, is the most common type of natural disaster accounting for about 40% of all natural disasters worldwide. A set of ten extreme indices is calculated for 51 stations throughout the South Island for the period 1951-2003. The west-east division is found to be the dominant feature of extreme precipitation trends for all extreme indices with more frequent and more intense extreme precipitation in the west/southwest and with a declining trend in the east. The significant decrease in extreme precipitation frequency was detected in Canterbury with 3 days less of precipitation above the long-term 95th percentile by 2003 as compared to 1951. The variability of precipitation, expressed by the SPI, is correlated with local New Zealand atmospheric circulation indices and large-scale teleconnections. The precipitation variability in the South Island is governed largely by the local circulation characteristics, mainly the strength and position of the westerly flow. The increase in precipitation in the West and SouthEast is associated with enhanced westerlies. The correlations between New Zealand�s circulation indices and regional SPI are seasonally robust. The SouthEast region exhibits a strong relationship with the Southern Oscillation Index on seasonal and annual time scales,and with Interdecadal Pacific Oscillation at the decadal scale. The predictability of seasonal precipitation one season ahead is very limited.

Precipitation is one of the most important components contributing to hydrological dynamics. Spatially distributed precipitation data can be obtained by satellite, radar, rain gages, etc, to serve various purposes. Currently, the most commonly used precipitation data still rely on gage-based measurement techniques that provide timely precipitation information with high quality and reliability. The National Oceanic and Atmospheric Administration (NOAA) and its cooperative climate stations are the primary resources of this form of precipitation data at the federal level. For hydrological simulation of precipitation-runoff for a watershed, precipitation is a critical model input that has a significant impact on the certainty and accuracy of simulation. To better understand the hydrological process within Whitewater River Basin in Kansas, the Precipitation-Runoff Model System (PRMS) was applied to this area, where the Cooperative Atmosphere-Surface Exchange Study (CASES) has set up an intensively instrumented site managed by Hydrologic Science Team (HST) of Oregon State University for rainfall data collection. Two rainfall data sources, NOAA and HST, were used in this study to simulate the stream response to rainfall within the basin. Different simulation results were acquired compared and analyzed. The study concluded that better simulation results were obtained with MMS-PRMS using integrated spatially distributed precipitation data, which was not available as a standard NOAA product. For a large basin, it is necessary to collect precipitation data within the area of interest in addition to standard NOAA data to produce an accurate hydrological model. It was suggested that to guarantee the quality of precipitation-runoff simulation using MMS-PRMS, the coverage of each rain gage should not be larger than 40 to 50 square kilometers (about 15-20 square miles). It was also learned that the precipitation data from local supplementary measurements are unlikely to be a satisfactory substitute for current NOAA data in hydrological simulation due to the short time period of measurement. The combination of standard NOAA data and additional data from an intensively measured site, such as CASES, or from radar, would allow more for better simulation. / Graduation date: 2004

Environmental flows are important to maintain the ecological integrity of the estuary. In a watershed, it is influenced by land use land cover (LULC) change, climate variability, and water regulations. San Antonio, Texas, the 8th largest city in the US, is likely to affect environmental flows to the San Antonio Bay/Guadalupe Estuary, due to rapid urbanization. Time series analysis was conducted at several stream gauging stations to assess trends in hydrologic variables. A bootstrapping method was employed to estimate the critical value for global significance. Results suggested a greater number of trends are observed than are expected to occur by chance. Stream gauging stations present in lower half of the watershed experienced increasing trend, whereas upper half experienced decreasing trends. A similar spatial pattern was not observed for rainfall. Winter season observed maximum number of trends. Wavelet analysis on hydrologic variables, suggested presence of multi-scale temporal variability; dominant frequencies in 10 to 15 year scale was observed in some of the hydrologic variables, with a decadal cycle. Dominant frequencies were also observed in 17 to 23 year scale with repeatability in 20 to 30 years. It is therefore important to understand various ecological processes that are dominant in this scale and quantify possible linkages among them. Genetic algorithm (GA) was used for calibration of the Hydrologic Simulation Program in FORTRAN (HSPF) model. Although, GA is computationally demanding, it is better than manual calibration. Parameter values obtained for the calibrated model had physical representation and were well within the ranges suggested in the literature. Information from LANDSAT images for the years 1987, 1999, and 2003 were introduced to HSPF to quantify the impact of LULC change on environmental flows. Modeling studies indicated, with increase in impervious surface, peak flows increased over the years. Wavelet analysis pointed, that urbanization also impacted storage. Modeling studies quantified, on average about 50% of variability in freshwater inflows could be attributed to variation in precipitation, and approximately 10% of variation in freshwater inflows could be attributed to LULC change. This study will help ecologist, engineers, scientist, and politicians in policy making pertinent to water resources management.

Precipitation is one of the atmospheric variables that characterize the climate of a region. The South Island of New Zealand (SI of NZ) has an unusually large number of distinct regional climates and its climatic diversity includes the coldest, wettest, driest and windiest places in New Zealand. This thesis focuses on identifying precipitation trends and rainfall fluctuations for the SI of NZ. First, homogeneity of 184 precipitation series is assessed with the combination of three homogeneity tests (Standard Normal Homogeneity Test, Easterling & Peterson test, Vincent�s Multiple Linear Regression). More than 60% of tested time series are found to contain at least one inhomogeneity. About 50% of the inhomogeneities can be traced to information in the station history files with nearly 25% of all inhomogeneities caused by the relocation of the precipitation gauge. Five coherent precipitation regions are defined by the Principal Component Analysis. The objective of identifying the periods of water deficit and surplus in spatial and temporal domains is achieved by using Standardized Precipitation Index (SPI). The SPI series (for 3, 6, 12, 24 and 48 months time scales) are calculated for each region and used for analysis of dry and wet periods. Clear differences in the frequency, length and intensity of droughts and wet periods were found between individual regions. There is a positive (i.e. increase in wet periods) trend in SPI time series for the North, Westland and Southland regions during the 1921-2003 period at all times scales, and a negative trend for Canterbury during the same period. The results show longer wet periods than dry periods at all time scales. Extreme heavy precipitation, which causes floods, is the most common type of natural disaster accounting for about 40% of all natural disasters worldwide. A set of ten extreme indices is calculated for 51 stations throughout the South Island for the period 1951-2003. The west-east division is found to be the dominant feature of extreme precipitation trends for all extreme indices with more frequent and more intense extreme precipitation in the west/southwest and with a declining trend in the east. The significant decrease in extreme precipitation frequency was detected in Canterbury with 3 days less of precipitation above the long-term 95th percentile by 2003 as compared to 1951. The variability of precipitation, expressed by the SPI, is correlated with local New Zealand atmospheric circulation indices and large-scale teleconnections. The precipitation variability in the South Island is governed largely by the local circulation characteristics, mainly the strength and position of the westerly flow. The increase in precipitation in the West and SouthEast is associated with enhanced westerlies. The correlations between New Zealand�s circulation indices and regional SPI are seasonally robust. The SouthEast region exhibits a strong relationship with the Southern Oscillation Index on seasonal and annual time scales,and with Interdecadal Pacific Oscillation at the decadal scale. The predictability of seasonal precipitation one season ahead is very limited.

Thesis (M. S.)--Florida State University, 2006. / Advisor: James J. O'Brien, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed Sept. 21, 2006). Document formatted into pages; contains ix, 40 pages. Includes bibliographical references.

Orientador: Jonas Teixeira Nery / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-26T17:34:38Z (GMT). No. of bitstreams: 1 Moraes_MarianadePaulaCosta_M.pdf: 5384378 bytes, checksum: 414ac09e6dc389556660bcb8ff419718 (MD5) Previous issue date: 2014 / Resumo: O estudo da variabilidade pluvial no Vale do Paraíba é uma importante ferramenta, uma vez que essa região está localizada numa área com dinâmicas climáticas peculiares que acabam gerando os casuais desastres naturais. Os principais desastres que ocorrem nesta região são as enchentes e inundações, pois a estrutura do seu relevo em vale acaba facilitando as enchentes e ocasionando alguns escorregamentos também. Neste contexto, a chuva torna-se a principal causadora dos desastres no Vale do Paraíba. Em anos de eventos extremos como El Niño, La Nina e ZCAS as chuvas ficam mais intensas e aumentam as chances de desastres nessa região, visto a cidade de São LuIZ do Paraitinga que sofreu com chuvas intensas na virada do ano 2009 para 2010, ocasionando uma das maiores enchentes da história da cidade. Esse fato despertou o interesse em estudar algumas cidades da região, as dinâmicas climáticas e a sua variabilidade pluvial, procurando entender o que aconteceu e relacionando com a variabilidade da região em geral. Para o estudo da variabilidade pluvial, a estatística descritiva foi uma importante ferramenta, além de programas como Excel, Surfer, Variowin e Climatol. Os dados de precipitação retirados para a pesquisa foram encontrados no site da Agência Nacional de Águas. Dentro dos objetivos do trabalho, constatou-se que a ocupação de maneira irregular associada às chuvas intensas provocam enchentes e outros desastres naturais. Isso se deve a urbanização da região, que é crescente e como consequência, há o aumento da população, principalmente em áreas de risco. Foram analisadas algumas enchentes na região nas cidades de Guaratinguetá, São Luiz do Paraitinga e Cunha / Abstract: The study of rainfall variability in the Paraíba Valley is an important tool, since this region is located in an area with peculiar climate dynamics that have been generating casual natural disasters. Major disasters occurring in this region are the floods and floods, because the structure of its emphasis on facilitating just valley floods and landslides causing some too. In this context, the rain becomes the main cause of disasters in the Paraíba Valley. In years of extreme events such as El Nino, La Nina and SACZ rains become more intense and increase the chances of disaster in the region, as the city of Sao Luiz do Paratinga that suffered from heavy rains at the turn of the year 2009 to 2010, causing a the biggest flood in the history of the city. This fact has sparked interest in studying some cities of the region, climate dynamics and its variability rain, trying to understand what happened and relating to the variability of the region in general. To study the rain variability, descriptive statistics was an important tool, along with programs like Excel, Surfer, and Variowin Climatol. Rainfall data taken for research are found in the National Water Agency website. Within the objectives of the study, it was found that the occupation irregularly associated with heavy rains leading to floods and other natural disasters. This is due to the urbanization of the region, which is growing and as a result, there is a growing population, especially in areas of risk. Some flooding in the region were analyzed in the cities of Guaratingueta, São Luiz do Paratinga and Cunha / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestra em Geografia