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1
Gbobaniyi, Emiola Olabode. "Transferability of regional climate models over different climatic domains." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/4854.
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Includes abstract.Includes bibliographical references (p. 119-144).
In the continuing quest to improve climate model predictions to meet the increasing demand for knowledge on the regional effects of global climate change, it is pertinent to increase our understanding of how the underlying processes of climate are represented in the models we use to make these predictions. Concerted efforts in model evaluations and intercomparison have provided numerous insights into various model biases which plague current state-of-the-art regional climate models (RCMs). Model evaluation and assessment is crucial to model development and understanding how physical processes are represented in models is necessary for improving model parameterizations. This thesis explored model transferability as a new approach for systematic process-based intercomparison of RCMs. It investigated an untested transferability hypothesis which states that “for non-monsoon regions experiencing weak synoptic scale forcing, the height of the cloud base is correlated with the daytime surface fluxes”. An initial transferability experiment was conducted over Cabauw, the Netherlands (51.97°N, 4.93°E) to assess the models’ skill in resolving the diurnal and seasonal cycles and to investigate the simulated connections between surface and hydrometeorological variables over a non-monsoon station. The ability of models to resolve these cycles correctly is a good metric of their predictive capabilities. The data used for the study comprises three-hourly surface observations for the period October 2002 – December 2004 from the Coordinated Enhanced Observing Period (CEOP) measuring campaigns of the Global Energy and Water Cycle Experiment (GEWEX) and three-year simulations (2002 -2004) from five RCMs (CLM, GEMLAM, MRCC, RCA3 and RSM). In simulating seasonal and diurnal cycles of CBH and surface variables, the European models (CLM and RCA3) demonstrate a clear home advantage over the North American models (GEMLAM, MRCC and RSM). Principal component analysis revealed that the models couple the cloud base height with surface fluxes as in observations and that this coupling is not sensitive to changes in wind speed. This study found that summer daytime loadings gave the strongest couplings of variables. Three major processes were identified over Cabauw. First and most dominant is the surface energy process which couples sensible and latent heat with net radiation. The second process is thermodynamic, coupling temperature and surface moisture (specific humidity), and the third is a dynamic process which couples pressure and wind speed. A model intercomparison was then carried out across the six midlatitude domains to test the validity of the Cabauw findings. In observations, CBH is well coupled with the surface fluxes over Cabauw, Bondville, Lamont and BERMS, but coupled only with temperature over Lindenberg and Tongyu. All the models (except GEMLAM) simulated a good coupling with surface fluxes at all stations. In GEMLAM, there is no coupling between CBH and surface fluxes at any station. In less homogenous domains of the study, a very slight decrease in the strength of coupling is seen in most of the models, under strong large scale forcing. This would suggest that the coupling between cloud base height and surface fluxes in the models is possibly more influenced by radiative forcing than by synoptic controls. This second study confirmed the findings at Cabauw that the simulated cloud base is correlated with surface energy fluxes and the sign of the correlations in the models is as in observations. This finding is important for the modeling community as it establishes the fact that the models are actually simulating the direction of influence of surface fluxes and possibly, soil water variability, on cloud processes.
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Salazar-Ferrer, Olivier. "Climatic variability and aperiodic behaviour: low order climate models and dynamical reconstruction." Doctoral thesis, Universite Libre de Bruxelles, 1989. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213250.
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Cain, Russell. "The climatic significance of tropical forest edges and their representation in global climate models." Thesis, Durham University, 2009. http://etheses.dur.ac.uk/302/.
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An emerging theme in global climate modelling is whether land covers created in the clearance of tropical humid forests influence water exchange between remnant forest patches and the atmosphere, and, if so, how this affects regional and global water exchange. Fieldwork presented in this thesis ascertains whether the amount of water transferred to the atmosphere from a humid tropical forest situated in Sabah, Northern Borneo, Malaysia, differs between its edge and interior due to the influence of surrounding clearings through horizontal heat transfer. Using satellite imagery to measure the shape and size of tropical forests, field measurements of water transfer were extrapolated to continental and global levels to infer how differences in water exchange with the atmosphere between forest edges and interiors may influence regional and global forest-atmosphere water exchange. Mean sap flow in trees within 50 meters of a forest-clearing boundary was found to be 73% greater than that in trees further into the forest; an observation supported by the decreased canopy temperature also recorded there. Evaporation from the forest canopy constituted a high fraction of annual rainfall (33%), but showed no edge effect similar to that of sap flow. Edge plots, however, expressed evapotranspiration rates 22% lower than forest interiors (657-890 mm yr-1), owing to the lower number and size of trees there. One edge plot, however, exhibited evapotranspiration 49.5% greater than that of forest interiors. Gradients of air temperature, vapour pressure deficit and wind speed from the adjacent clearing to the forest interior indicated that warm, dry air moving from the clearing to the forest was the most credible cause of increased sap flow of trees near the forest edge. This hypothesis was supported by a strong correlation between the amount of vapour in the air moving from the clearing and tree water use. It was estimated that the influence of differences in water transfer to the atmosphere between the edges and interiors of tropical forest would not alter global water transfer to the atmosphere by more than 0.25-4%, or by 4-7% in the most fragmented tropical continent, Africa. However, it remains unclear whether the inclusion of tropical forest edge effects within climate models is necessary, as the pioneering nature of this thesis, and of existing studies reviewed within it, means that solid conclusions will be dependent upon future work. This thesis concludes with suggestions for future research that will most effectively consolidate the provisional conclusions and recommendations herein.
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Santer, B. D. "Regional validation of General Circulation Models." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383549.
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Graham, Stephen Thomas. "Continental river routing for fully coupled climate system models /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3024456.
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Pasquali, Flavia. "State space models for the analysis and forecasting of climatic time series." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23081/.
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We analyse climatic time series with state space models in order to compute the forecast distribution. The task is challenging since the temperature series are characterised by large temporal and cross-sectional dimensions. We modify and apply the three-step method proposed in Li et al. Journal of Econometrics 2020, which exploit the cross information in order to improve prediction.
We fit the linear Gaussian state space model to different univariate time series, estimating the model parameters with the Kalman filter and computing the prediction errors. The prediction error time series are then jointly analysed by means of a dynamic factor model. The estimation procedure follows the two-step approach suggested by Doz, Giannone, and Reichlin in the context of macro-economic time series nowcasting. Finally, the simulation smoother by Durbin and Koopman allows to sample scenarios conditional on the observed time series and to reconstruct the forecast distribution.
The results we obtained are promising. They demonstrate the feasibility of the entire procedure. Our explorations involved just a climatic parameter (the maximum temperature) and a reduced sample of data (8 years on a weekly basis for twenty climatic stations) , but we preliminarily tested the whole approach on much longer time series - up to 150 years - with a richer cross-sectional structure - up to 10.000 stations - experiencing viable computational times and very promising estimation results.
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Pérez, Navarro Maria Ángeles. "Plant species climatic niche and its relationship with population responses to extreme drought." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/669559.
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Understanding how climate affects species’ distribution and performance is a central issue in ecology since its origins. In last decades, however, the interest in this question
has been reactivated by the current context of climate change. Species Niche Modelling has been widely used to assess shifts in species distribution and to test the relationship
between species’ climatic niche and species physiological and demographic performance. Nevertheless it is still largely undetermined whether these models can portray population and community responses, particularly in relation to extreme climatic episodes. In this thesis I aim at exploring the capacity of niche modelling to predict species decay under extreme climatic conditions, particularly droughts, addressing some constraints of this approach and proposing possible solutions. To achieve this goal, I counted with 3 vegetation decay datasets measured in the Spanish SE after the extreme drought year 2013-2014. In the second chapter I used different Species Distribution Model (SDMs) algorithms to estimate species’ climatic suitability before (1950-2000) and during the extreme drought, in order to test the possible correlation between suitability and decay, and whether the existence of this relationship depended on the applied SDM algorithm. I consistently found a positive correlation between remaining green canopy and species’ climatic suitability
before the event, suggesting that populations historically living closer to their species’ tolerance limits are more vulnerable to drought. Contrastingly, decreased climatic suitability during the drought period did not correlate with remaining green canopy, likely because of extremely low climatic suitability values achieved during the exceptional climatic episode. In order to test whether this extremely low suitability values could derive as a consequence of only considering climatic averages when calibrating SDMs, in the thired chapter I developed a method to include inter-annual climatic variability into niche characterization. I then compared the respective capacities of climatic suitabilities obtained from averaged-based and from inter-annual variability-based niches to explain demographic responses to extreme climatic events. I found that climatic suitability obtained from both niches quantifications significantly explained species demographic responses. However, climatic suitability from inter-annual variability-based niches showed higher explanatory capacity, especially for populations that tend to be more geographically marginal. In the fourth chapter I tried to overcome the inability of the SDMs to predict populations decay during extreme conditions, by using Euclidean distances to species’ niche in the environmental space. I compared the capacities of both population distances in the climatic environmental space and population climatic suitability derived from SDMs to explain population observed demographic responses to an extreme event. I found that SDMs-derived suitability failed to explain population decay while distances to the niche centroid and limit significantly explained population die-off, highlighting that population displaced farther from species’ niche during the extreme episode showed higher vulnerability to drought. In the fifth chapter, I used species niche characterizations in the environmental space and demographic data to
address the impact of extreme events at community level. Particularly, I estimated the community climatic disequilibrium before and after a drought episode. I found that extreme drought nested within a decadal trend of increasingly aridity led to a reduction in community climatic disequilibrium.
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Serefiddin, Feride Schwarcz H. P. "Paleoclimate models for western North America as inferred from speleothem isotope records /." *McMaster only, 2003.
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Tidwell, Amy C. "Assessing the impacts of climate change on river basin management a new method with application to the Nile river/." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/19830.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007.Committee Chair: Georgakakos, Aris; Committee Member: Fu, Rong; Committee Member: Peters-Lidard, Christa; Committee Member: Roberts, Phil; Committee Member: Sturm, Terry; Committee Member: Webster, Don.
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Zeng, Ning. "Climatic impact of Amazon deforestation: A study of underlying mechanism through simple modeling." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186999.
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An intermediate level model for tropical climatology including atmosphere-land-ocean interaction is developed. The model contains basically linearized steady state primitive equations with simplified thermodynamics. A simple hydrological cycle is also included. Special attention has been paid to land surface processes in attempting to study climate change caused by Amazon deforestation. In comparison with previous simple modeling work on tropical climatology or anomaly, the present model is more sophisticated in the sense that it predicts all the important meteorological variables with little input, while being computationally simple. The modeled tropical climatology appears to be realistic. The model generally better simulates the ENSO anomaly compared to many previous simple model simulations. We provide analysis of model results and discuss model deficiencies and possible improvements of the model. The climatic impact of Amazon deforestation is studied in the context of this model. Model results show a much weakened Atlantic Walker/Hadley circulation as a result of the existence of a strong positive feedback loop in the atmospheric circulation system and the hydrological cycle. The regional climate is very sensitive to albedo change and sensitive to evapotranspiration change. The pure dynamical effect of surface roughness on convergence is small, but the surface flow anomaly displays intriguing features. Analysis of the thermodynamic equation reveals the balance among convective heating, adiabatic cooling and radiation largely determines the deforestation response. The model provides a plausible mechanism for the common results of many GCM simulations. Studies of the consequences of hypothetical continuous deforestation suggest that the replacement of forest by desert may be able to sustain a desert-like climate. When a simple mixed layer ocean model is coupled with the atmospheric model, the results suggest a 1 °C decrease in SST gradient across the equatorial Atlantic ocean in response to Amazon deforestation. The magnitude of the decrease depends on the coupling strength.
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Santoso, Agus Mathematics & Statistics Faculty of Science UNSW. "Evolution of climate anomalies and variability of Southern Ocean water masses on interannual to centennial time scales." Awarded by:University of New South Wales. School of Mathematics and Statistics, 2005. http://handle.unsw.edu.au/1959.4/33355.
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In this study the natural variability of Southern Ocean water masses on interannual to centennial time scales is investigated using a long-term integration of the Commonwealth Scientic and Industrial Research Organisation (CSIRO) coupled climate model. We focus our attention on analysing the variability of Antarctic IntermediateWater (AAIW), Circumpolar DeepWater (CDW), and Antarctic Bottom Water (AABW). We present an analysis of the dominant modes of temperature and salinity (T - S) variability within these water masses. Climate signals are detected and analysed as they get transmitted into the interior from the water mass formation regions. Eastward propagating wavenumber-1, -2, and -3 signals are identied using a complex empirical orthogonal function (CEOF) analysis along the core of the AAIW layer. Variability in air-sea heat uxes and ice meltwater rates are shown by heat and salt budget analyses to control variability of Antarctic Surface Water where density surfaces associated with AAIW outcrop. The dominant mode in the CDW layer is found to exhibit an interbasin-scale of variability originating from the North Atlantic, and propagating southward into the Southern Ocean. Salinity dipole anomalies appear to propagate around the Atlantic meridional overturning circulation with the strengthening and weakening of North Atlantic Deep Water formation. In the AABW layer, T - S anomalies are shown to originate from the southwestern Weddell Sea, driven by salinity variations and convective overturning in the region. It is also demonstrated that the model exhibits spatial patterns of T - S variability for the most part consistent with limited observational record in the Southern Hemisphere. However, some observations of decadal T - S changes are found to be beyond that seen in the model in its unperturbed state. We further assess sea surface temperature (SST) variability modes in the Indian Ocean on interannual time scales in the CSIRO model and in reanalysis data. The emergence of a meridional SST dipole during years of southwest Western Australian rainfall extremes is shown to be connected to a large-scale mode of Indian Ocean climate variability. The evolution of the dipole is controlled by variations in atmospheric circulation driving anomalous latent heat uxes with wind-driven ocean transport moderating the impact of evaporation and setting the conditions favourable for the next generation phase of an opposite dipole.
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Edelstein, Christopher. "Climatic conditions and storm hydrology of a small agricultural watershed." Virtual Press, 2005. http://liblink.bsu.edu/uhtbin/catkey/1314224.
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Climatic conditions (precipitation, evapotranspiration, available soil moisture, and temperature) are important variables when considering cumulative storm streamflow for a watershed. The objective of this study was to determine what climatic conditions, if any, could be used to mathematically model cumulative storm streamflow for an extensively-drained small agricultural watershed in northwest Delaware County, Indiana. A water-level recorder was installed in Killbuck Creek during autumn 2002, spring, summer, and autumn 2003 and 2004. To determine discharge, velocity measurements were collected following US Geological Survey (USGS) methods and two rating curves (high and low flow) were constructed. Simple linear regressions were performed using cumulative streamflow as the dependent variable and precipitation, evapotranspiration, available soil moisture, temperature, and runoff as independent variables. Multiple linear regressions were used to examine combinations of the independent variables. Cumulative streamflow was most related to precipitation (r2 = 0.23 and p < 0.001) and least related to temperature (r2 = 0.03 and p < 0.5). The multiple linear regression from the combination of precipitation, runoff, and temperature provided the most accurate cumulative streamflow simulation (R2 = 0.53 and p < 0.001). Multiple linear regressions using climatic variables can be used to estimate cumulative streamflow for an agricultural watershed.Department of Natural Resources and Environmental Management
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Paulino, Silvia Elisandra Pasqua. "Modelos agrometeorológicos para estimação do número de frutos por planta em cultivares de laranja doce na região de Limeira-SP." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-17052005-165526/.
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O estabelecimento de modelos que permitam previsões de tendências de produtividade, apontando se as colheitas serão menores ou maiores, é de grande importância para todos os elos da cadeia citrícola. Este trabalho teve por objetivo identificar e avaliar a influência de variáveis agrometeorológicas, em diferentes fases do ciclo da cultura, para propor modelos empíricos para estimação do número de frutos por planta nas variedades cultivadas de laranja doce Pêra, Valência e Hamlin, na região de Limeira-SP. Foram utilizados dados amostrais de número de frutos por planta, em três classes de idade, referentes à estimativa anual de produção da indústria de suco paulista, no total de 15 safras (1990/91 a 2004/05), e dados meteorológicos (temperatura máxima e mínima e precipitação) para o município de Limeira (22º32S, 47º27W, 639 metros). Foram determinados inicialmente os coeficientes de correlação linear entre número de frutos por planta e variáveis agrometeorológicas componentes do balanço hídrico e temperatura, em diferentes períodos. Foram desenvolvidos modelos de regressão linear múltipla, mediante procedimento stepwise, para os subconjuntos de variáveis agrometeorológicas que apresentaram as maiores correlações significativas com o número de frutos por planta em diferentes fases do ciclo da cultura. As condições meteorológicas durante as fases de crescimento vegetativo de verão, pré-florescimento, florescimento e início de crescimento dos frutos, influenciam a produção de frutos por planta. Os modelos obtidos apresentaram ajustes satisfatórios entre valores observados e estimados, com coeficiente de determinação variando de 0,72 a 0,87.The establishment of models that allows forecasting of yield tendencies, pointing if the harvest will be minors or majors, is important for the citrus industry. This work had the purpose of evaluating the influence of meteorological variables in different phases of the crop cycle to propose empirical models to estimate the number of fruits per plant on the cultivated varieties of sweet orange Pêra, 'Valência' and Hamlin, to the region of Limeira-SP, Brazil. Samples of number of fruits per plant have been used, classified in three age classes, related to the annual juice production estimative from citrus industry of the State of São Paulo, on the total of 15 harvests (1990/91 to 2004/05), and meteorological data of maximum and minimum air temperature and precipitation of Limeira-SP (22º32'S, 47º27'W, 639 meters), Brazil. The correlation coefficients among number of fruits per plant and meteorological variables components of the water balance and air temperature in different periods were initially computed. The linear multiple regression models were developed using 'stepwise' procedure, for all variables that presented the major significant correlations with the number of fruits per plant in different phases of the crop cycle. The meteorological conditions during the phases of vegetative growth of summer, pre-flowering, flowering and beginning of fruits growth influenced the fruits per plant production. The proposed models presented satisfactory adjustments among observed and estimated values, with determination coefficients from 0.72 to 0.87.
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Nicholson, Lindsey. "Modelling melt beneath supraglacial debris : implications for the climatic response of debris-covered glaciers." Thesis, University of St Andrews, 2005. http://hdl.handle.net/10023/10264.
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Understanding how debris-covered glaciers respond to climate is necessary in order to evaluate future water resources and glacier flood hazard potential, and to make sense of the glacier chronology in mountain regions, In order achieve this, it is necessary to improve the current understanding of how surface debris affects glacier ablation rate, and to develop methods by which the ablation of debris-covered glaciers can be predicted under various climatic scenarios. This thesis develops a numerical surface energy balance model that uses simple meteorological data to calculate melt beneath a debris layer of given thickness and thermal characteristics. Field data from three contrasting sites demonstrate that the assumptions made within the model concerning the thermal properties of supraglacial debris are valid during most ablation conditions and that model performance is considerably better than previous models. Model results indicate that the effect of debris on melt rate is highly dependent on meteorological conditions. Under colder climates, thin debris can accelerate ice melt by extending the ablation period at both diurnal and seasonal scales. However, in milder mid- summer conditions, even a very thin debris cover inhibits melt rate compared to that of exposed ice. The new melt model is applied to produce the first quantified ablation gradients for debris- covered glaciers, and to model the evolution of ice surfaces under a debris layer of variable thickness. Modelled ablation gradients are qualitatively similar to hypothetical ones outlined previously, and quantitatively similar to those measured in the field. The ablation gradients are used to explore the factors affecting the response of debris-covered glaciers to climate change. Beneath a debris layer of variable thickness, the melt model produced ablation topography, as observed in the field, which underwent topographic inversion over time in response to debris redistribution. Debris thickness variability was found to cause calculated ablation rate to increase compared to that calculated using a mean debris thickness by one to two orders of magnitude, suggesting that melt calculations made on the basis of spatially averaged debris thickness may be inaccurate.
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Flesch, Aaron D., Philip C. Rosen, and Peter Holm. "Long-term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation." Wiley, 2017. http://hdl.handle.net/10150/626024.
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Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates. Among terrestrial species, abundances of a short-lived, winter-spring breeder increased markedly by an estimated 2375285% across time, while two larger spring-summer breeders with higher thermal preferences declined by up to 64%. Abundances of two arboreal species that occupy shaded and thus sheltered microhabitats fluctuated but did not decline systematically. Abundances of all species increased with precipitation at short lag times (151.5 yrs) likely due to enhanced food availability, but often declined after periods of high precipitation at longer lag times (254 yrs) likely due to predation and other biotic pressures. Although rising maximum daily temperatures (Tmax) are expected to drive global declines of lizards, associations with Tmax were variable and weak for most species. Instead, abundances of all species declined with rising daily minimum temperatures, suggesting degradation of cool refugia imposed widespread metabolic or other costs. Our results suggest climate warming and drying are having major impacts on lizard communities by driving declines of species with traits that augment exposure to abiotic extremes and by modifying species interactions. The complexity of patterns we report indicate that evaluating and responding to the influence of climate change on biodiversity must consider a broad array of ecological processes.
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Zhang, Yan. "The radiative effect of aerosols from biomass burning on the transition from dry to wet season over the amazon as tested by a regional climate model." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26510.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009.Committee Chair: Fu, Rong; Committee Member: Dickinson, Robert E.; Committee Member: Nenes, Athanasios; Committee Member: Webster,Peter J.; Committee Member: Yu, Hongbin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Yang, Wen. "Drought Analysis under Climate Change by Application of Drought Indices and Copulas." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/716.
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Drought is a recurrent extreme climate event with tremendous hazard for every specter of natural environment and human lives. Drought analysis usually involves characterizing drought severity, duration and intensity. Similar to most of the hydrological problems, such characteristic variables are usually not independent. Copula, as a model of multivariate distribution, widely used in finance, actuarial analysis, has won increasingly popularity in hydrological study. Here, the study has two major focuses: (1) fit drought characteristics from Streamflow Drought Index (SDI) or Standardized Runoff Index (SRI) to appropriate copulas, then using fitted copulas to estimate conditional drought severity distribution and joint return periods for both historical time period 1920-2009 and future time period 2020-2090. SDI is calculated based on long term observed streamflow while SRI is based on simulated future runoff. Parameters estimation of marginal distribution and copulas are provided, with goodness fit measures as well; (2) investigate the effects of climate change on the frequency and severity of droughts. In order to quantify the impact, three drought indices have been proposed for this study to characterize the drought duration, severity and intensity changes under the climate change in Upper Klamath River Basin. Since drought can be defined as different types, such as meteorological drought, agricultural drought, hydrological drought and social economical drought, this study chooses Standardized Precipitation Index (SPI), Palmer Drought Severity Index (PDSI) and Surface Water Supply Index (SWSI) to estimate the meteorological, agricultural and hydrological drought, respectively. Climate change effects come from three sources: the inherent reason, the human activity and the GCMs uncertainties. Therefore, the results show the long term drought condition by calculating yearly drought indices, and compared in three ways: First, compare drought characteristics of future time periods with base period; second, show the uncertainties of three greenhouse gas emission scenarios; third, present the uncertainties of six General Circulation Models (GCMs).
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Briesemeister, Roberta. "Modelagem matematica para o estudo do oidio em uma plantação de soja sob os efeitos do CO2." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/307575.
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Orientador: Laercio Luis VenditeDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica
Made available in DSpace on 2018-08-08T21:33:03Z (GMT). No. of bitstreams: 1 Briesemeister_Roberta_M.pdf: 814655 bytes, checksum: bf6c5b877276e48f013d98984a004dde (MD5) Previous issue date: 2007
Resumo: As recentes mudanças climáticas no planeta, estão promovendo alterações na ocorrência e desenvolvimento de doenças de plantas. O principal gás causador desse acontecimento é o dióxido de carbono, CO2. Baseado neste fato, foi desenvolvido pela Embrapa Meio Ambiente, um experimento que trabalha com cenários futuros, tendo em vista a quantidade de CO2 presente na atmosfera. Preliminarmente foi feita uma análise estatística dos dados, verificando a área foliar lesionada, a altura das plantas primárias de soja, a nodulação e o peso seco. Com os resultados obtidos nessa análise, observamos que havia uma diferença significativa no tamanho da área foliar lesionada quando exposto a níveis diferentes de CO2. À partir desses dados, foi elaborado um modelo matemático determinístico para a previsão do crescimento da área foliar lesionada, causada pelo oídio, acoplando na taxa de crescimento da lesão a influência da quantidade de CO2. Algumas simulações foram feitas utilizando o crescimento da quantidade de CO2 da atmosfera. Com os dados existentes de anos anteriores, observamos em todos os casos, que altos níveis de CO2, provocam uma diminuição na área foliar lesionada. Muito embora exista uma diminuição nessa área, a quantidade do patógeno cresce exponecialmente no tempo. O que nos faz concluir, que em cenários futuros, haverá uma grande dissiminação na doença da soja, provocada pelo oídio
Abstract: The recently climate changes of the planet are promoving alteration in the incident and development in the plants diseases. The main gas that cause this event is the carbon dioxide, CO2. Based in this fact, it was developed by Embrapa environmental, the experiment that works with futures scenarios, looking the quality of CO2 present in the atmosphere. First of all it was made a statistic analyses of datas, verifing the leaf area that was damned, the hights of the primary soybeans plants, the nodulation and the dry weight. With the results that was gotten in this analyses, we could notice that it had a significant difference in the size of the leafs area damned when it was expose in differents levels of CO2. Starting from this datas, it was elaborated a deterministical mathematic model for crop the growing leaf area damned, caused by mildew, coupled in the growing rate of the damned area the influence of the CO2 quantity. Some simulation it were done using the growing quantity of CO2 in the atmosphere. With the presents datas of the years, we observe that in all cases, that hight level of CO2 cause the reduction of the damned leafs area. Even thought exists a reduction in this area, the quantity of pathogen grows exponentially in the times. What make us conclude, that in futures scenarios, will have a big spread in the soybean disease, caused py mildew
Mestrado
Mestre em Matemática Aplicada
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Worton, Adrian J. "Using mathematical models to understand the impact of climate change on tick-borne infections across Scotland." Thesis, University of Stirling, 2016. http://hdl.handle.net/1893/24918.
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Ticks are of global interest as the pathogens they spread can cause diseases that are of importance to both human health and economies. In Scotland, the most populous tick species is the sheep tick Ixodes ricinus, which is the vector of pathogens causing diseases such as Lyme borreliosis and Louping-ill. Recently, both the density and spread of I. ricinus ticks have grown across much of Europe, including Scotland, increasing disease risk. Due to the nature of the tick lifecycle they are particularly dependent on environmental factors, including temperature and habitat type. Because of this, the recent increase in tick-borne disease risk is believed to be linked to climate change. Many mathematical models have been used to explore the interactions between ticks and factors within their environments; this thesis begins by presenting a thorough review of previous modelling of tick and tick-borne pathogen dynamics, identifying current knowledge gaps. The main body of this thesis introduces an original mathematical modelling framework with the aim to further our understanding of the impact of climate change on tick-borne disease risk. This modelling framework takes into account how key environmental factors influence the I. ricinus lifecycle, and is used to create predictions of how I. ricinus density and disease risk will change across Scotland under future climate warming scenarios. These predictions are mapped using Geographical Information System software to give a clear spatial representation of the model predictions. It was found that as temperatures increase, so to do I. ricinus densities, as well as Louping-ill and Lyme borreliosis risk. These results give a strong indication of the disease risk implications of any changes to the Scottish environment, and so have the potential to inform policy-making. Additionally, the models identify areas of possible future research.
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Warner, Gary E. "Predicting pedestrian use on outdoor urban plazas utilizing climate/behavior models." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-12302008-063811/.
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Enríquez, Alonso Aarón. "Evaluación de modelos climáticos: el comportamiento de la variable nubosidad." Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/392164.
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Las nubes constituyen uno de los fenómenos más importantes en cuanto a la regulación de la radiación entrante y saliente de la Tierra y por ende, del clima. El principal objetivo de esta tesis es analizar cómo se reproduce el comportamiento de la cobertura total de nubes en los modelos climáticos de circulación general (GCM), y compararlo con los datos observacionales desde 1984 hasta 2005.
Se analiza el comportamiento climático de la nubosidad y las tendencias de todos los GCM que ofrecen salida de la cobertura de nubes (CMIP5) y se comparan frente a las observaciones. Se observa una subestimación generalizada por parte de los GCM respecto a las observaciones tanto a nivel global como regional (Mediterráneo). Además, las observaciones y los GCM muestran disminución de la nubosidad a latitudes medias especialmente en el Mediterráneo. Por último, se procede a estudiar escenarios futuros en dicha región.Clouds are one of the most important phenomena in terms of effect on the incoming and outgoing radiation of the planet and therefore, in regulating the climate. The main objective of this thesis is to analyze how general circulation models (GCMs) reproduce the behavior of the total cloud cover, compared against available observational data from 1984 to 2005. Then we analyze the global and regional behavior of the climate and trends of all GCMs that provide output of total cloud cover (CMIP5). Having analyzed the GCMs, we proceed to compare these datasets against the various observational databases. We observe a widespread underestimation by GCMs respect to observations, both globally and regionally (Mediterranean). In turn, observations and GCM show a general decrease of cloudiness at mid-latitude regions, especially in the Mediterranean. Finally, we proceed to study future scenarios in the region.
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Djalilvand, Hamid. "Growth response of Pinus resinosa and Picea abies to past and future climatic variations." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23997.
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Growth responses to climatic variables of red pine (Pinus resinosa Aiton) and Norway spruce (Picea abies L. Karst) were studied at the Morgan Arboretum, near Montreal, in southern Quebec, Canada (45$ sp circ$ 25$ sp prime$ N, 73$ sp circ$ 57$ sp prime$ W; 15.2 m above sea level). The relationships between climatic variables and basal area growth were examined using linear and quadratic models. Current and previous year's climatic variables were tested separately and in combination using multiple regression models. The best models explained 82% and 85% of the total variance of the growth of Norway spruce and red pine, respectively. The growth of both species was more associated with evapotranspiration than precipitation. The growth of Norway spruce was best explained by the current year's annual evapotranspiration (43%), while the growth of red pine was more related to previous year's August evapotranspiration (33%) at our site.The JABOWA model was used to predict tree growth in hypothetical climates which could result from global climate changes. Based on literature, five treatments were applied: normal, and increases of 1, 3, 5, and 10$ sp circ$C. Comparison between the last (1983-1992) and next (1993-2002) ten years growth showed no significant differences between species when temperature was normal or increased by 1 and 3$ sp circ$C, but significant differences between species were observed when the temperature was increased by 5$ sp circ$C. Both species declined when the temperature was increased by 10$ sp circ$C. We concluded that Norway spruce is more sensitive to increases in atmospheric temperatures than red pine at our site.
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Ashcraft, Ivan S. "Microwave Remote Sensing of the Greenland Ice Sheet: Models and Applications." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd532.pdf.
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Osei-Adjei, Peter. "Assessing the Potential Effects of Climate Variability on Reservoir Water Volume in North-Central Texas Using GIS and Models: A Case Study of Ray Roberts Lake." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4910/.
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Assessing the impact of climate variability on water resources is one of the difficult tasks in planning the future growth of North-Central Texas. This study defined twelve extreme climate scenarios. Data from each scenario was input to a hydrological model (HEC-HMS) to calculate watershed runoff to Lake Ray Roberts. Model parameters are determined using Geographic Information System (GIS). The water balance was calculated for current and future water demand and resulting change in the volume and level of this reservoir. The results indicate certain climate scenarios decrease in volume. Thus, local governments should plan alternative water management strategies during droughts.
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Furtado, Jason C. "On the uncertainties and dynamics of Pacific interannual and decadal climate variability and climate change." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37302.
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Tropical and extratropical Pacific decadal climate variability substantially impact physical and biological systems in the Pacific Ocean and strongly influence global climate through teleconnection patterns. Current understanding of Pacific decadal climate variability centers around the El Niño-Southern Oscillation (ENSO), the Aleutian Low (AL), and the Pacific Decadal Oscillation (PDO). However, recent literature has highlighted the emerging roles of secondary modes of variability of the tropical and extratropical Pacific atmosphere and ocean in global climate change: the Central Pacific Warming (CPW) phenomenon, the North Pacific Oscillation (NPO), and the North Pacific Gyre Oscillation (NPGO). This work analyzes the statistics and uncertainties behind Pacific interannual and decadal-scale climate variability, and focuses on better understanding the roles of the CPW, NPO, and NPGO in the climate system.
The study begins by examining the dynamics of the NPO and its role in Pacific interannual and decadal climate variability. Results illustrate that the individual poles of the NPO have relations at high frequencies, but only the southern node contains a deterministic low-frequency component, which is forced by tropical Pacific sea surface temperature (SST) variability, as shown with a modeling experiment. The NPO-induced variability by the tropical Pacific SST is then integrated by the underlying ocean surface to form the decadal-scale NPGO signal. Thus, a new link between the CPW, the NPO, and the NPGO is formed, expanding the current framework of Pacific decadal variability and its implications for weather and climate.
The new framework of North Pacific decadal variability (NPDV) is then evaluated in 24 state-of-the-art coupled climate models. Results indicate that the models in general have difficulty reproducing the leading modes of NPDV in space and time, particularly the NPGO mode and its connection to the NPO. Furthermore, most models lack the proper connections between extratropical and tropical Pacific, for both the ENSO/AL/PDO and CPW/NPO/NPGO connections. Improvements in these teleconnections are thus needed to increase confidence in future climate projections.
The last part of the dissertation explores further the importance of the CPW mode by comparing and contrasting two popular paleoclimate SST anomaly reconstruction methods used for tropical Indo-Pacific SSTs. The first method exploits the high correlation between the canonical ENSO mode and tropical precipitation; the second method uses a multi-regression model that exploits the multiple modes of covariability between tropical precipitation and SSTs, including the CPW mode. The multi-regression approach demonstrates higher skill throughout the tropical Indo-Pacific than the first approach, illustrating the importance of including the CPW phenomenon in understanding past climates.
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Hamlet, Alan F. "Hydrologic implications of 20th century warming and climate variability in the western U.S. /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10132.
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Baldwin, Elizabeth. "Modelling preferences in economics." Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:8abebfd3-58df-4223-83b8-ce2f43b5dc90.
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This thesis considers the economics of preferences in two different contexts. First it examines damages from climate change. I argue that our ignorance of the welfare implications of higher levels of warming, as well as scientific uncertainty in precisely what might trigger these scenarios, imply that our tastes and beliefs are incomplete (in the sense of Galaabaatar and Karni, 2013). That is, there are many 'plausible' ways to evaluate a given scenario. In Chapter 1, then, I develop this theory, and use it to formally separate climate impacts into three sorts: those understood well, those understood badly, and those representing the worst possible scenario. I provide a generalisation of the 'dismal theorem' of Weitzman (2009a), and address the question of policy choice: prices versus quantities (cf. Weitzman, 1974). Chapter 2 is an example of the analysis propounded in Chapter 1. I explore the sensitivity of the social cost of carbon to assumed damages from 4C warming, to the assumed extent of CO2 emissions, and to the modelling of the climate and carbon cycles. The analysis shows that differing prior assumptions can alter our evaluation of policy by orders of magnitude. The second part of this thesis regards preferences for indivisible goods. In Chapter 3, which is joint work with Paul Klemperer, I introduce to this field the 'tropical hypersurface', being those prices at which an agent's demand changes. Simple geometric features of this set tell us the precise trade-offs that interest the agent. Thus we develop a new taxonomy of valuations, `demand types'; familiar notions such as substitutes and complements are examples. Finally, we provide a necessary and sufficient condition on these `demand types' for existence of competitive equilibrium, which implies several existing results, as well as new and quite different examples.
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Bottomley, Gregory Edward. "Modeling the dynamic behavior of rain attenuation." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/90918.
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This thesis addresses the problem of predicting satellite path rain fade duration statistics for an arbitrary location, frequency, elevation angle and polarization. It summarizes the development of a dynamic stochastic model. From this model a technique is derived for predicting fade duration statistics for one site using measured attenuation data at another site. This technique is evaluated by comparing predicted and experimental results for several locations, frequencies, elevation angles and polarizations.M.S.
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Olofsson, Erika. "Supporting management of the risk of wind damage in south Swedish forestry /." Alnarp : Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200646.pdf.
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Backéus, Sofia. "Forest management strategies for CO₂ mitigation." Umeå : Department of Forest Resource Management, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200989.pdf.
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Pedro, Thiago Bernardo. "Estudo dos fatores clim?ticos e ambientais associados ? ocorr?ncia de carrapatos Amblyomma sculptum (Acari: Ixodidae) adultos na mesorregi?o metropolitana do Rio de Janeiro." Universidade Federal Rural do Rio de Janeiro, 2015. https://tede.ufrrj.br/jspui/handle/jspui/1751.
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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq
This study evaluates the influence of climatic variables on the occurrence distribution of Amblyomma sculptum adult ticks in four sample areas in Serop?dica and Mangaratiba, two municipalities in Rio de Janeiro Metropolitan mesoregion. The data used is relative to tick sampling between the spring of 2008 and the winter of 2012. The climatic variables included in the study were mean temperature, relative humidity and rainfall, in the day of sampling and in the 15 days prior to each sampling. For the statistical analysis, four types of generalized linear models were used: Poisson, Negative Binomial, Quasi Poisson (?2) and Zero Inflated Poisson (ZIP). A total of 574 ticks were found, most of them in the autumn. The bivariate analysis between each one of the independent variables and the response variable, tick count, showed seven variables that were significant at least in two types of models (being ZIP one of them): temperature in the day before sampling, temperature between the 4th and 6th days prior to sampling, temperature between the 11th and 15th days prior, humidity in the day before sampling, humidity in 5th day before, humidity between the 9th and 12th days prior and rainfall in the 12th day prior to sampling. These variables were combined in the multivariate analysis, therewith, nine models were fitted. Analyzing the prevalence ratio (PR), Akaike Information Criterion (AIC), mean square of residuals (MSR) and correlation between expected Y and observed Y (Corr), the best model was chosen, with the following variables (PR [CI 90%]): temperature between the 11th and 15th days prior to sampling (1,06 [1,01; 1,11]), humidity in the day before (1,04 [1,02; 1,05]) and rainfall in the 12th day prior to sampling (0,97 [0,94; 0,99]). Regarding the fitted models, it was possible to notice that the most satisfactory parameters were presented by ZIP models, in which the MSR values were the lowest and Corr values were the highest. The bivariate analyzes performed as of ZIP models contrasted the fact that temperature acts as a protection factor for the occurrence of A. sculptum adult ticks in the day of sampling and in the two days before, but it acts as a risk factor form the 3rd to the 15thday before. Humidity and rainfall act as protection factors for tick occurrence as from the 3rd and the 5th day prior to sampling, respectively. In the days closer to sampling, these two latter variables did not show a definite conduct of risk or protection with respect to the studied tick occurrence. Within this context, we conclude that understanding the parameters responsible for controlling the life cycle of A. sculptum is essential to generate risk models of disease transmission
O presente estudo avalia a influ?ncia de vari?veis clim?ticas sob a distribui??o de ocorr?ncia de carrapatos Amblyomma sculptum adultos em quatro ?reas amostrais nos munic?pios de Serop?dica e Mangaratiba, na mesorregi?o Metropolitana do Rio de Janeiro. Foram utilizados dados referentes a coletas de carrapatos realizadas entre a primavera de 2008 e o inverno de 2012. As vari?veis clim?ticas consideradas foram temperatura m?dia, umidade relativa do ar e volume de precipita??o, no dia das coletas e nos 15 dias anteriores a cada coleta. Para a an?lise estat?stica, foram utilizados quatro tipos de modelos de regress?o lineares generalizados: Poisson, Binomial Negativa, Extra Poisson (?2) e Poisson Inflacionada de Zeros. Foram coletados, ao todo, 574 carrapatos, sendo a maioria no outono. A an?lise bivariada entre cada uma das vari?veis explicativas e a vari?vel de desfecho, contagem de carrapatos, apresentou sete vari?veis significativas em pelo menos dois modelos (sendo um deles o ZIP): temperatura no dia anterior ? coleta, temperatura entre o 4? e o 6? dia anterior, temperatura entre o 11? e o 15? dia anterior, umidade no dia anterior ? coleta, umidade no 5? dia anterior, umidade entre o 9? e o 12? dia anterior e precipita??o no 12? dia anterior ? coleta. Essas vari?veis foram combinadas na an?lise multivariada, com isso, nove modelos foram ajustados. Atrav?s da an?lise da raz?o de preval?ncia (RP), Akaike Information Criterion (AIC), quadrado m?dio dos res?duos (QMR) e correla??o entre Y esperado e Y observado (Corr), foi escolhido o melhor modelo, com as seguintes vari?veis (RP [IC 90%]): temperatura entre o 11? e o 15? dia antes da coleta (1,06 [1,01; 1,11]), umidade no dia anterior ? coleta (1,04 [1,02; 1,05]) e precipita??o no 12? dia anterior (0,97 [0,94; 0,99]). Considerando-se os modelos ajustados, foi poss?vel observar que os par?metros mais satisfat?rios foram apresentados pelos modelos ZIP, em que os valores de QMR foram os mais baixos, e os valores de Corr, os mais elevados. As an?lises bivariadas realizadas a partir do modelo ZIP destacaram o fato de que a temperatura se apresenta como fator de prote??o para a ocorr?ncia de A. sculptum adultos no dia da coleta e nos dois dias anteriores, mas como fator de risco a partir do 3? dia anterior at? o 15?. J? umidade e precipita??o apresentam-se como fatores de prote??o para a ocorr?ncia de carrapatos a partir do 3? e do 5? dia anterior ? coleta, respectivamente, at? o 15?. Nos dias mais pr?ximos ? coleta, essas duas ?ltimas vari?veis n?o apresentam um comportamento definido de risco ou prote??o em rela??o ? ocorr?ncia dos carrapatos em estudo. Dentro desse contexto, conclui-se que entender os par?metros que controlam o ciclo de vida de A. sculptum ? essencial para a gera??o de modelos de risco de transmiss?o de doen?as
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Garedew, Efrem. "Land-use and land-cover dynamics and rural livelihood perspectives, in the semi-arid areas of Central Rift Valley of Ethiopia." Umeå : Dept.of Forest Resource Management, Swedish University of Agricultural Sciences, 2010. http://epsilon.slu.se/201007.pdf.
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Saenger, Casey Pearce. "Low-latitude Western North Atlantic climate variability during the past millennium : insights from proxies and models." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55163.
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Thesis (Ph.D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-65).
Estimates of natural climate variability during the past millennium provide a frame of reference in which to assess the significance of recent changes. This thesis investigates new methods of reconstructing low-latitude sea surface temperature (SST) and hydrography, and combines these methods with traditional techniques to improve the present understanding of western North Atlantic climate variability. A new strontium/calcium (Sr/Ca) - SST calibration is derived for Atlantic Montastrea corals. This calibration shows that Montastrea Sr/Ca is a promising SST proxy if the effect of coral growth is considered. Further analyses of coral growth using Computed Axial Tomography (CAT) imaging indicate growth in Siderastrea corals varies inversely with SST on interannual timescales. A 440-year reconstruction of low-latitude western North Atlantic SST based on this relationship suggests the largest cooling of the last few centuries occurred from -1650-1730 A.D., and was -I°C cooler than today. Sporadic multidecadal variability in this record is inconsistent with evidence for a persistent 65-80 year North Atlantic SST oscillation. Volcanic and anthropogenic radiative forcing are identified as important sources of externally-forced SST variability, with the latter accounting for most of the 20th century warming trend. An 1800-year reconstruction of SST and hydrography near the Gulf Stream also suggests SSTs remained within about I°C of modern values. This cooling is small relative to other regional proxy records and may reflect the influence of internal oceanic and atmospheric circulation.
(cont.) Simulations with an atmospheric general circulation model (AGCM) indicate that the magnitude of cooling estimated by proxy records is consistent with tropical hydrologic proxy records.
by Casey Pearce Saenger.
Ph.D.
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Pokhrel, Pranav. "The Study of Temporal and Spatial Variability of Degree Day Factor of Snowmelt in Colorado." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849730/.
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Snowmelt is one of the major sources of surface water supply and ground-water recharge in high elevation areas and can also cause flooding in snow dominated watersheds. Direct estimation of daily snowmelt requires daily snow water equivalent (SWE) measurements that are not always available, especially in places without monitoring stations. There are two alternative approaches to modeling snowmelt without using direct measurements of SWE, temperature-based and energy-based models. Due to its simplicity, computational efficiency, and less input data requirement, the temperature-based method is commonly used than the energy-based method. In the temperature-index approach snowmelt is estimated as a linear function of average air temperature, and the slope of the linear function is called the degree-day factor (DDF). Hence, the DDF is an essential parameter for utilizing the temperature-based method to estimate snowmelt. Thereby, to analyze the spatial properties of DDF, 10 years DDF from the entire state of Colorado was calculated for this research. Likewise, to study the temporal properties, DDFs for 27 years from the White Yampa water basin and the Colorado Headwaters water basin were calculated.
As a part of the spatial analysis, the calculated DDFs were correlated with spatial variables (slope, aspect, latitude and elevation) and a spatial correlation graph was created to observe the possibility of predicting DDF. Also a multivariate regression model was prepared using these spatial variables to predict the DDF using spatial variables. Further, the DDFs calculated from Colorado headwaters and the White Yampa water basins were correlated for annual temporal variation, daily variation, variation with peak snow water equivalent and variation with important temporal cycles like accumulation period and melting period of snowmelt. The result obtained from this study showed that the variability of DDF is more dependent upon temporal factors compared to the spatial factors. Also, the results showed that predicting DDF is a difficult process and requires complex methods than simple linear models or multivariate models.
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Vilela, Tatiane Assis. "Avaliação do desmatamento e seus possíveis impactos nas mudanças climáticas da bacia do Rio Turvo Sujo - MG." Universidade Federal de Viçosa, 2009. http://locus.ufv.br/handle/123456789/3713.
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Previous issue date: 2009-02-17Fundação de Amparo a Pesquisa do Estado de Minas Gerais
This work investigates impacts of deforestation on the regional climatic changes of the Turvo Sujo River Basin, MG during the past 24 years. Landsat images of 1984, 1989, 2000 and 2008 were used to define the deforestation rate. Annual NDVI data ( Normalized Difference Vegetation Index ) for the period from 1984 to 2006 generated from NOAA satellites were used to generate deforestation tendency. This tendency was compared to temporal evolution of temperature and precipitation to investigate the impacts of deforestation on local climate changes. The results showed that vegetative area increased from 21.01% in 1984 to 24.00% in 1900, 29.56% in 2000 and 25.96% in 2008. It indicated that the studied basin was under reforestation during the years before 2000 which resulted a better climatic change but and deforestation and land degradation afterward. From the temporal evolution analysis, it was observed that NDVI was closed related to precipitation but inversely related to temperature. From the tendency analysis of NDVI, precipitation and temperature, it was observed that NDVI increased slightly from 6.60 to 6.64, precipitation from 1200 mm to 1220 mm and temperature from 19.6 °C to 20.5 °C. It is concluded that the time series of annual NDVI, generated from the NOAA satellites, provides us an important source to investigate the deforestation impacts on regional climatic changes as well as the reforestation effects on minimizing local climatic changes. It is suggested that suitable actions of reforestation and natural resources management should be taken to reverse the current tendency of temperature increase in the Basin.
Este trabalho investiga os impactos do desmatamento nas mudanças climáticas regionais da Bacia do Rio Turvo Sujo, localizada no estado de Minas Gerais, durante os últimos 24 anos. As imagens obtidas do sensor TM/Landsat referente aos anos de 1984, 1989, 2000 e 2008 foram usadas para calcular a taxa de desmatamento existente na área de estudo. Os dados de NDVI anuais ("Normalized Difference Vegetation Index ) referentes ao período de 1984 a 2006 gerados a partir do sensor NOAA/AVHRR foram empregados no cálculo da tendência de desmatamento. Esta tendência foi comparada a evolução temporal de temperatura e precipitação de forma a proporcionar uma análise dos impactos do desmatamento nas mudanças climáticas locais. Os resultados mostraram que a taxa do desmatamento foi reduzida e a área com cobertura vegetal aumentada de 21,01% em 1984 a 24,00% em 1989, 29.56% em 2000 diminuindo para 25.96% em 2008. Estes dados indicaram aumento do reflorestamento durante o período de 1984 a 2000 e uma tendência de desaceleração após 2000. Da análise da evolução temporal, foi observado que o NDVI relacionou-se diretamente com a precipitação, mas inversamente com a temperatura. Da análise de tendência do NDVI, da precipitação e da temperatura, foi observado que NDVI aumentou ligeiramente de 6.60 a 6.64, a precipitação de 1200 mm para 1220 mm e a temperatura de 19.6 °C para 20.5 °C. Concluiu-se que as séries temporais da média anual de NDVI geradas a partir do satélite NOAA provêem uma importante fonte de investigação dos impactos de desmatamento nas mudanças climáticas regionais como também o reflorestamento minimiza as mudanças climáticas locais. É sugerido que haja melhor administração dos recursos naturais e implantação de novas áreas de reflorestamento de forma a inverter a tendência atual de aumento da temperatura na na Bacia.
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O'Hara, Jeffrey Keith. "Water resources planning under climate change and variability." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3259069.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed June 21, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Nhemachena, Charles. "Agriculture and future climate dynamics in Africa impacts and adaptation options /." Thesis, Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-05302009-122839/.
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Waibel, Michael Scott. "Model Analysis of the Hydrologic Response to Climate Change in the Upper Deschutes Basin, Oregon." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/45.
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Considerable interest lies in understanding the hydrologic response to climate change in the upper Deschutes Basin, particularly as it relates to groundwater fed streams. Much of the precipitation occurring in the recharge zone falls as snow. Consequently, the timing of runoff and recharge depend on accumulation and melting of the snowpack. Numerical modeling can provide insights into evolving hydrologic system response for resource management consideration. A daily mass and energy balance model known as the Deep Percolation Model (DPM) was developed for the basin in the 1990s. This model uses spatially distributed data and is driven with daily climate data to calculate both daily and monthly mass and energy balance for the major components of the hydrologic budget across the basin. Previously historical daily climate data from weather stations in the basin was used to drive the model. Now we use the University of Washington Climate Impact Group's 1/16th degree daily downscaled climate data to drive the DPM for forecasting until the end of the 21st century. The downscaled climate data is comprised from the mean of eight GCM simulations well suited to the Pacific Northwest. Furthermore, there are low emission and high emission scenarios associated with each ensemble member leading to two distinct means. For the entire basin progressing into the 21st century, output from the DPM using both emission scenarios as a forcing show changes in the timing of runoff and recharge as well as significant reductions in snowpack. Although the DPM calculated amounts of recharge and runoff varies between the emission scenario of the ensemble under consideration, all model output shows loss of the spring snowmelt runoff / recharge peak as time progresses. The response of the groundwater system to changing in the time and amount of recharge varies spatially. Short flow paths in the upper part of the basin are potentially more sensitive to the change in seasonality. However, geologic controls on the system cause this signal to attenuate as it propagates into the lower portions of the basin. This scale-dependent variation to the response of the groundwater system to changes in seasonality and magnitude of recharge is explored by applying DPM calculated recharge to an existing regional groundwater flow model.
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Weldon, Alexander Nicholas. "A wine climate model : using climatic variables and GIS for viticulture potential." Thesis, University of Canterbury. Geography, 2003. http://hdl.handle.net/10092/2058.
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There have been numerous attempts for measuring viticulture potential. In most cases, this involves the construction of a climate/viticulture based model which is then applied to a potential region. Although these climatic based models may perform well inside their original regions, they tend to fail elsewhere. Discrepancies between climatic indexes have been attributed to many factors including vineyard management, grapevine variety, phenology/climate misconceptions and regional macro/mesoclimate regimes. The aim of this study is to investigate the viticulture potential within two regions of the South Island of New Zealand, by implementing several climatic based models. These models have been designed to improve the predictive accuracy over other current climatic/viticulture models. A GIS, along with climatic data collected from over 80 stations within Canterbury and the surrounding region, are incorporated into several models which are used within this project as viticultural tools to improve the current understanding between topographic, climatic and grapevine relationships. Viticulture potential ratings are then assessed for two overlapping regions; the smaller sub-region of the lower Waipara catchment and the larger Canterbury region. Results show that many of the current vineyard plots in the Canterbury and lower Waipara regions do not fall within the optimal limits of the models, while there are large potential areas in both regions yet to be utilized for viticulture. However, not all of Canterbury and the lower Waipara catchment can be used for viticulture due to several limiting factors such as elevation, risk of frosts and low mean temperatures. Surprisingly, most of the Canterbury Plains fall within this 'no go' area. The model has proved to be a much more reliable tool than other existing climatic indexes such as the widely used degreeday and mean temperature of the warmest month indices.
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Dars, Ghulam Hussain. "Climate Change Impacts on Precipitation Extremes over the Columbia River Basin Based on Downscaled CMIP5 Climate Scenarios." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/979.
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Hydro-climate extreme analysis helps understanding the process of spatio-temporal variation of extreme events due to climate change, and it is an important aspect in designing hydrological structures, forecasting floods and an effective decision making in the field of water resources design and management. The study evaluates extreme precipitation events over the Columbia River Basin (CRB), the fourth largest basin in the U.S., by simulating four CMIP5 global climate models (GCMs) for the historical period (1970-1999) and future period (2041-2070) under RCP85 GHG scenario.
We estimated the intensity of extreme and average precipitation for both winter (DJF) and summer (JJA) seasons by using the GEV distribution and multi-model ensemble average over the domain of the Columbia River Basin. The four CMIP5 models performed very well at simulating precipitation extremes in the winter season. The CMIP5 climate models showed heterogeneous spatial pattern of summer extreme precipitation over the CRB for the future period. It was noticed that multi-model ensemble mean outperformed compared to the individual performance of climate models for both seasons.
We have found that the multi-model ensemble shows a consistent and significant increase in the extreme precipitation events in the west of the Cascades Range, Coastal Ranges of Oregon and Washington State, the Canadian portion of the basin and over the Rocky Mountains. However, the mean precipitation is projected to decrease in both winter and summer seasons in the future period.
The Columbia River is dominated by the glacial snowmelt, so the increase in the intensity of extreme precipitation and decrease in mean precipitation in the future period, as simulated by four CMIP5 models, is expected to aggravate the earlier snowmelt and contribute to the flooding in the low lying areas especially in the west of the Cascades Range. In addition, the climate change shift could have serious implications on transboundary water issues in between the United States and Canada. Therefore, adaptation strategies should be devised to cope the possible adverse effects of the changing the future climate so that it could have minimal influence on hydrology, agriculture, aquatic species, hydro-power generation, human health and other water related infrastructure.
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Nemeth, Michael W., and University of Lethbridge Faculty of Arts and Science. "Climate change impacts on streamflow in the upper North Saskatchewan River Basin, Alberta." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, c2010, 2010. http://hdl.handle.net/10133/2477.
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This research focuses on the estimation of the impacts of climate change on water yield, streamflow extremes, and the streamflow regimes in the Cline River Watershed, and consequently, water availability for hydropower generation in this area. The Cline River Watershed comprises the flow into Lake Abraham, the reservoir for Bighorn Dam, is part of the upper North Saskatchewan River basin (UNSRB).
This objective was achieved by parameterizing the ACRU agro-hydrological modelling system. After parameterization was complete, ACRU output was calibrated and verified against available observed data, including temperature, snow water equivalent, glacier mass balance, potential evapotranspiration, and streamflow data. After ACRU was properly verified, five selected climate change scenarios to estimate impacts of climate change in this area. Overall water yields are projected to increase over time. A large shift in seasonality is likely the biggest impact climate change will have on water resources in the Cline River Watershed.xii, 126 leaves : ill., maps ; 29 cm
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Kuenzi, Maribeth. "AN INTEGRATED MODEL OF WORK CLIMATE." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2530.
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Management scholars have become increasingly interested in the role of organizational context. As part of this trend, research on work climates has thrived. This contemporary climate research differs from traditional approaches by concentrating on facet-specific climate types like service or innovation, rather than general, global conceptualizations of climate. Consequently, the climate literature has become fragmented and disorderly. I seek to remedy this in my dissertation. Specifically, I propose and test an integrated model of work climate that examines both molar and facet-specific climates. Chapter 1 is a review of the organizational work climate literature. This review seeks to review, reorganize, and reintegrate the climate literature. In addition, this review brought to light an issue that hinders the integration of the climate literatures: the literature does not contain a quality instrument for assessing the general characteristics of the molar work climate of an organization. In Chapter 2, I develop a theoretically-driven measure of work climate by drawing on the competing values framework (Quinn & Rohrbaugh, 1983). Preliminary results from three studies suggest that the proposed four-component model of molar work climate appears to be viable. The results indicate the instrument has internal reliability. Further, the results demonstrate discriminant, convergent, and criterion-related validity. In Chapter 3, I propose and test an integrated model of work climate by drawing on bandwidth-fidelity theory (Cronbach & Gleser, 1957). I predict that facet-specific climates will be more strongly related to specific outcomes and molar climates will be more strongly related to global outcomes. Further, I suggest weaker, indirect relationships between molar climate and specific outcomes and between facet-specific climates and global outcomes. The results indicate support for my predictions.Ph.D.
Department of Management
Business Administration
Business Administration PhD
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Bendini, Hugo do Nascimento. "Processamento digital de imagens para inferência de risco de doença fúngica da bananicultura." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/518.
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Previous issue date: 2012-06-11Financiadora de Estudos e Projetos
The digital image processing has been used to solve a significant number of problems in the agricultural sector, especially with the evolution of remote sensing systems. This work presents a computational model based on digital image processing and remote sensing to infer about the risk in the agricultural environment. To validate the method, a experimental study was conducted about the risk of fungal disease in banana plantations. Temporal series of meteorological and monitoring data of the disease, organized in classes for the definition of probability distribution models, based on polynomial functions were used to validate results as well as satellite images integrated by fusion techniques, geometric corrections and re-sampling with interpolators based on kriging techniques. Fusion methods by IHS (Intensity, Hue, and Saturation) and PCA (Principal Component Analysis) and the Gaussian models, exponential and cylindrical for the ordinary kriging were tested. The IHS fusion technique demonstrated to be more interesting in relation the PCA technique, with correlation coefficients between bands 2, 3 and 4 originals and hybrids, of 0.2318, 0.0304 and 0.1800, respectively. The method of ordinary kriging for re-sampling of the images showed better results when adjusted by the Gaussian model. The proposed method is feasible to the development of risk maps of disease occurrence, since confer spatial and temporal variability in relation to the model existing on the literature for the region.
O processamento de imagens digitais tem auxiliado na solução de um expressivo número de problemas do setor agrícola, sobretudo com a evolução dos sistemas de sensoriamento remoto. Este trabalho tem por objetivo apresentar um modelo computacional baseado em processamento digital de imagens e sensoriamento remoto para inferência de risco em ambiente agrícola. Para validação do método, foi realizado estudo experimental sobre o risco de ocorrência da doença fúngica em bananais. Foram utilizadas séries temporais de dados meteorológicos e de monitoramento da doença, organizados em classes para a definição de modelos de distribuição de probabilidades, baseados em funções polinomiais, bem como imagens de satélites, organizadas com técnicas de fusão, correções geométricas e re-amostragem, com interpoladores baseados em técnicas de krigagem. Foram testados os métodos de fusão por IHS (Intensity, Hue, Saturation) e PCA (Principal Component Analysis), bem como os modelos gaussiano, exponencial e cilíndrico para a krigagem ordinária. A técnica de fusão por IHS demonstrou-se mais interessante em relação à técnica por PCA, apresentando coeficientes de correlação entre as bandas 2, 3 e 4 originais e híbridas, de 0,2318, 0,0304 e 0,1800, respectivamente. O método de krigagem ordinária para reamostragem das imagens apresentou melhores resultados quando ajustado pelo modelo gaussiano. A metodologia proposta se apresentou viável e adequada para a elaboração de mapas de risco de ocorrência da doença, uma vez que conferece variabilidade espacial e temporal ao modelo já existente na literatura para aquela região.
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Bergamin, Rodrigo Scarton. "Variação espacial e temporal de espécies arbóreas em florestas da Mata Atlântica : perspectivas sobre o efeito das mudanças climáticas e planejamento da conservação." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/170132.
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Distintos padrões de composição de espécies de plantas podem ser observados ao longo de metacomunidades, pois espécies variam de acordo com os diferentes tipos de ambiente e também com a distância geográfica, dado o processo de dispersão. Ainda, estes mecanismos podem causar variação temporal na composição ou abundância de espécies em um sítio devido a alterações que estes mecanismos podem sofrer. Compreender como as mudanças na composição de espécies no espaço, definida como beta diversidade, ou no tempo estão relacionadas ao clima passado, atual ou futuro podem ajudar no planejamento de conservação de uma região. Assim, esta tese esta dividida em quatro capítulos e aborda questões relacionadas com mudanças espaçotemporais na composição de espécies sob uma perspectiva de planejamento de conservação e mudanças climáticas na Mata Atlântica. O primeiro capítulo apresenta um banco de dados com a informação de ocorrência de 1917 espécies de plantas arbóreas distribuídas em 206 comunidades na Mata Atlântica, em diferentes formações florestais (Floresta Atlântica stricto sensu (s.s.), Floresta com Araucária e Floresta Estacional). O segundo capítulo relacionou padrões de beta diversidade com a efetividade da rede de áreas protegidas nas formações florestais do sul da Mata Atlântica (Floresta Atlântica, Floresta com Araucária e Floresta Estacional). Encontramos altos valores de turnover e baixo aninhamento para todas as formações florestais, por isso recomendamos que esforços adicionais precisam almejar o aumento no número de áreas protegidas, especialmente para a Floresta com Araucária e a Floresta Estacional. A maioria das áreas protegidas no sul da Mata Atlântica estão concentradas na região leste, priorizando a Floresta Atlântica s.s. O terceiro capítulo trouxe novas perspectivas sobre a dinâmica da Floresta com Araucária no tempo através da modelagem de nicho ecológica. Durante as flutuações climáticas do Quaternário, estudos palinológicos indicavam uma expansão da Floresta com Araucária, porém nossos resultados demonstraram uma retração da área de cobertura desta floresta, principalmente nas zonas de contato com outras formações florestais. Também observamos que futuramente, se a temperatura continuar aumentando como previsto, a Floresta com Araucária sofrerá uma drástica redução na sua distribuição. Por fim, o capítulo quatro investigou como as espécies de árvores estão respondendo aos efeitos de mudanças climáticas em parcelas permanentes localizadas em ecótonos de florestas Atlânticas. Os resultados mostram que espécies tropicais estão migrando em direção a áreas de maior altitude, ou seja mais frias. Espécies tropicais que já ocorrem em áreas vi de Floresta com Araucária estão apresentando maiores taxas de recrutamento e crescimento, e menor mortalidade do que espécies temperadas, características da Floresta com Araucária.Distinct patterns of plant species composition can be observed along metacommunities, as species vary in relation to different types of environment and also to the geographic distance, given the dispersal process. These mechanisms may yet lead temporal variation in species composition or abundance in a given place due to fluctuations on these mechanisms. Understanding how changes in species composition across the space, defined as beta diversity, or in time are related with past, current and future climate changes can help conservation planning in a given region. Thus, this thesis is divided into four chapters and discusses shifts in species composition across space and time under the perspective of conservation planning and climate changes in the Atlantic Forest. The first chapter shows a database with 1917 tree species occurrence distributed in 206 sites across distinct forest formations in the Atlantic Forest biome (Atlantic Rainforest, Araucaria Forest and Seasonal Forest). The second chapter related beta diversity patterns with the effectiveness of the current network of protected areas in southern Brazilian Atlantic forests (Atlantic Rainforest, Araucaria Forest and Seasonal Forest). We found high values of turnover and low nestedness for all forest formations, thus additional conservation efforts must target an increase in the number of protected areas, especially for the Araucaria Forest and the Seasonal Forest. Most protected areas are currently limited to the eastern region and prioritize the Atlantic Rainforest. The third chapter brought new insights about the Araucaria Forest dynamics in time through ecological niche models. During the climatic fluctuations of the Quaternary, palynological studies indicated an expansion of the Araucaria Forest, however our results demonstrated an overall retraction of the cover area, mainly in boundary zones with other forest formations. Yet, we showed that in the future, if the temperature continues to increase as expected, the Araucaria Forest would suffer a drastic reduction in its distribution. Finally, the fourth chapter investigated how tree species are responding to climatic changes in permanent plots located in Atlantic forests ecotones. Our results showed that tropical species are migrating towards to colder areas in higher altitudes. Tropical species that already occur in Araucaria Forest areas are even presenting higher rates of recruitment and growth, and lower mortality than temperate species characteristics from the Araucaria Forest.
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Halmstad, Andrew Jason. "Investigating Future Variation of Extreme Precipitation Events over the Willamette River Basin Using Dynamically Downscaled Climate Scenarios." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/327.
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One important aspect related to the management of water resources under future climate variation is the occurrence of extreme precipitation events. In order to prepare for extreme events, namely floods and droughts, it is important to understand how future climate variability will influence the occurrence of such events. Recent advancements in regional climate modeling efforts provide additional resources for investigating the occurrence of extreme events at scales that are appropriate for regional hydrologic modeling. This study utilizes data from three Regional Climate Models (RCMs), each driven by the same General Circulation Model (GCM) as well as a reanalysis dataset, all of which was made available by the North American Regional Climate Change Assessment Program (NARCCAP). A comparison between observed historical precipitation events and NARCCAP modeled historical conditions over Oregon's Willamette River basin was performed. This comparison is required in order to investigate the reliability of regional climate modeling efforts. Datasets representing future climate signal scenarios, also provided by NARCCAP, were then compared to historical data to provide an estimate of the variability in extreme event occurrence and severity within the basin. Analysis determining magnitudes of two, five, ten and twenty-five year return level estimates, as well as parameters corresponding to a representative Generalized Extreme Value (GEV) distribution, were determined. The results demonstrate the importance of the applied initial/boundary driving conditions, the need for multi-model ensemble analysis due to RCM variability, and the need for further downscaling and bias correction methods to RCM datasets when investigating watershed scale phenomena.
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Pimentel, Franciele de Oliveira. "Clima urbano: o uso de modelos geoespaciais na investigação do comportamento térmico em Juiz de Fora- MG." Universidade Federal de Juiz de Fora (UFJF), 2017. https://repositorio.ufjf.br/jspui/handle/ufjf/5618.
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A preocupação com os chamados impactos ambientais urbanos fomentou um maior interesse nas pesquisas, principalmente aquelas voltadas para as análises climáticas, na escala urbana. A cidade por consequência de seu processo de organização e estruturação desenvolveu um clima totalmente particular, o clima urbano, isso é possível através da retirada da vegetação original e a inserção dos chamados equipamentos urbanos, como por exemplo, as vias impermeabilizadas, as construções, a verticalização, além da circulação de pessoas e veículos que irão contribuir para maior aquecimento da atmosfera local. Os materiais presentes no meio urbano vão apresentar diferentes valores de albedo, emissividade, absortividade e irradiação e consequentemente, estes condicionarão diferentes valores de temperatura de superfície e que influenciarão na temperatura do ar. O presente estudo tem por objetivo analisar o comportamento do clima urbano na cidade de Juiz de Fora- MG, onde foram trabalhadas 35 regiões urbanas, localizadas ao longo do curso do Rio Paraibuna. O estudo busca através da aplicação de um modelo geoespacial, interligar variáveis que possuem uma conexão direta com a temperatura de superfície e indireta com a temperatura do ar. Este conjunto de dados permitiu alcançar uma maior compreensão, viabilizou a espacialização e consequentemente uma visualização de como se distribuem as áreas e suas diferentes capacidades de criarem distintos campos térmicos na cidade.Além disso, para fins de validação do modelo, foi feita uma correlação estatística entre o modelo matemático proposto e a temperatura de superfície obtida na faixa do infravermelho termal. O modelo utilizado provou possuir consistência para ser adaptado a fim de ser replicado em diferentes cidades com especificidades térmicas além de ser viável a integração de outras informações e dados.
Concern about so-called urban environmental impacts has fostered greater interest in research, especially those focused on climate analysis, on the urban scale. The city as a result of its process of organization and structuring has developed a totally particular climate, the urban climate, this is possible through the removal of the original vegetation and the insertion of so-called urban equipment, such as waterproofed roads, constructions, verticalization, besides the circulation of people and vehicles that will contribute to greater warming of the local atmosphere. The materials present in the urban environment will present different values of albedo, emissivity, absorptivity and irradiation and consequently, these will condition different values of surface temperature and that will influence the air temperature. The present study aims to analyze the behavior of the urban climate in the city of Juiz de Fora- MG, where 35 urban areas were located along the course of the Paraibuna River. The study searches through the application of a geospatial model, interconnecting variables that have a direct coexistence with the surface temperature and indirect with the air temperature. This dataset allowed to reach a greater understanding, made possible the spatialization and consequently a visualization of how the areas are distributed and their different capacities to create different thermal fields in the city. In addition, for purposes of validation of the model, a statistical correlation was made between the proposed mathematical model and the surface temperature obtained in the thermal infrared range. The model used proved to have consistency to be adapted in order to be replicated in different cities with thermal specificities besides being feasible the integration of other information and data.
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Graves, David. "An Assessment of the Impacts of Climate Change on the Upper Clackamas River Basin with a Distributed Hydrologic Model." PDXScholar, 2005. https://pdxscholar.library.pdx.edu/open_access_etds/2432.
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The Pacific Northwest is dependent on seasonal snowmelt for water resources that support a significant portion of its economy. Increased temperatures resulting from higher concentrations of atmospheric greenhouse gases may cause disruptions to these resources because of reductions in the annual snowpack and variations of the timing of snowmelt. This study reconstructs and applies a GIS-based distributed hydrologic model at a monthly scale to assess the effects of future climate change on runoff from the Upper Clackamas River Basin (located near Portland, Oregon). Historic flow data and snow measurements are used to calibrate and test the perfonnance of the hydro logic model for a contemporary period (1971-2000), and the model is run for two future scenarios (2010-2039 and 2070-2099) using IS92 climate change scenarios from two global climate circulation models (Hadley and Canadian Centre for Climate) as inputs.
The results forecast that mean peak snowpack in the study area will drop dramatically (36% to 49% by 2010-2039, and 83% to 88% by 2070-2099), resulting in earlier runoff and diminished spring and summer flows. Increases to mean winter runoff by by the 2070-2099 period vary from moderate (13.7%) to large (46.4%), depending on the changes to precipitation forecasted by the global climate circulation models. These results are similar to those of other studies in areas dependent on snowpack for seasonal runoff, but the reductions to snowpack are more severe in this study than similar studies for the entire Columbia Basin, presumably because the elevations of much of the Upper Clackamas Basin are near the current mid-winter snow line.
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Pereira, Janini. ""Variabilidade do Oceano Austral usando um modelo acoplado de circulação geral"." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/21/21132/tde-24102003-125856/.
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Neste trabalho a variabilidade climatica do oceano Austral e a ocorrencia da Onda Circumpolar Antartica (OCA) sao investigadas. Foram usados os dados de uma simulaçao do modelo numerico acoplado do Nacional Centre for Atmospheric Research/ Community System Model - NCAR CCSM de 150 anos, e um conjunto de dados climatologicos como base de comparaçao dos dados do modelo. estes foram obtidos da Re-analise do NCEP/NCAR (National Center for Envirommental Prediction) para o periodo de janeiro de 1948 a julho de 2002. Com o intuito de analisar o comportamento sazonal e anual foram analisadas as climatologias e utilizada a tecnica de analise harmonica das variaveis de temperatura da superficie do mar (TSM), pressao ao nivel do mar (PNM), componentes meridional (Vy) e zonal (Vx) do vento. Para analisar o comportamento interanual dessas variaveis sao utilizados diagramas Hovmoeller, espectros de potencia, alem de tecnicas estatisticas como Empirical Ortogonal Functions (EOF) e singular Value Decomposition (SVD).In this study the climatic variability of the Southern ocean and the Antarctic Circumpolar Wave (ACW) are investigated. The National Center for Atmospheric Research/ Community System Model _ NCAR CCSM coupled model 150 years simulation data is compered with the climatology data from the Nacional Center for Envirommental Prediction - NCEP/NCAR Re-analysis, for a period from january/1948 until july/2002. Annual and seasonal climatology and harmonic analysis are used for the following variables: sea surface temperature (SST), sea level pressure (SLP), meridional and zonal wind. Hovmoeller diagrams, potencial spectra and statistics methods such as Empirical Ortogonal Functions (EOF) and Singular Value Decomposition (SVD) are used to analyze changes in interannual behavior of this variables.
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Matzneller, Philipp. "Klimawandel und Sauerkirschanbau." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2016. http://dx.doi.org/10.18452/17472.
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In dieser Arbeit wurden die Veränderungen der agrarklimatologischen Bedingungen im Zuge des Klimawandels für ausgesuchte Sauerkirschanbauregionen in Europa und Nordamerika untersucht. Es wird auf veränderte Risiken (Spätfrost, Hitzewellen, Wassermangel) hingewiesen, die durch nachhaltige, praxisorientierte und ökonomisch vertretbare Anpassungsmaßnahmen (Überdachung, Frostschutz, Bewässerung, Anbausystem, Wahl der Sorte und Unterlage, etc.) begrenzt werden können. Der Klimawandel kann neben Risiken aber auch Chancen für den Sauerkirschanbau eröffnen. Höhere Temperaturen und eine längere Vegetationsperiode können regional differenziert zu günstigeren Anbaubedingungen führen. Ein besonderer Schwerpunkt wurde auf die Entwicklung phänologischer Modelle gelegt, mit denen Veränderungen im Entwicklungsrhythmus der Sauerkirschgehölze analysiert werden konnten. Dafür wurden acht Modelle zur Vorhersage des Blühbeginns und Blühendes entwickelt. Weitere phänologische Stadien konnten mit dem Modell von Zavalloni et al. (2006) berechnet werden. Die Untersuchungen haben ergeben, dass sich der Blühbeginn unter geänderten Klimabedingungen verfrüht, aber nur geringe Verkürzungen der Zeiträume zwischen den phänologischen Stadien zu erwarten sind. Zu den gefürchteten Witterungsschäden im Obstbau gehört Spätfrost, der zu hohen Ertragsverlusten führen kann. Im Zuge des Klimawandels können sich die Häufigkeit und Stärke der Fröste ändern. Die Frostwahrscheinlichkeit während der untersuchten Entwicklungsphasen von Sauerkischgehölzen könnte in diesem Jahrhundert in Rheinland-Pfalz und Eau Claire abnehmen, während sich die Verhältnisse in den anderen Anbaugebieten nur geringfügig ändern. In einem zweiten Schritt wurden die Ertragsverluste durch Frost bestimmt. Hierbei hat sich ergeben, dass die Frostschäden in den untersuchten Anbauregionen wahrscheinlich geringer werden. Allerdings differieren die Ergebnisse zwischen den Berechnungen mit beobachteten und modellierten Temperaturen oft stark.This thesis investigates the changes in agro-climatic conditions for selected growing region in Europe and North America under current and future climate conditions. The overall aim of the study was to identify possible risks (spring frosts, heat waves, water shortages), which can be limited by sustainable, practically oriented and economically viable adaptation measures (hail- and frost-protection, irrigation, cultivation system, choice of variety and rootstock). Besides risks, climate change can provide new opportunities. Higher temperature levels and extended growing season lengths could regionally differentiated improve the growing conditions. Particular focus was given to developing phenological models, used to investigate shifts in spring phenology of sour cherry trees due to climate change. Therefore, eight models to predict the beginning and end of blossom were optimized and validated. Further phenological stages were calculated with the model by Zavalloni et al. (2006). The results show an earlier onset in the beginning of sour cherry blossom under future climate conditions, while the length of the period between the phenological stages only shortens slightly. Spring frosts are feared weather hazards in orchards which can cause substantial yield losses. The changing climate conditions could influence the frequency and strength of spring frosts. In the course of this century the spring frost probability is likely to decrease in Rhineland-Palatinate and Eau Claire, while only slight changes are expected in the other growing regions. In the second step, yield losses caused by spring frost were calculated. The frost damages on sour cherries in the investigated growing regions will probably decrease. However, the yield losses calculated with observed and modeled temperatures often differ strongly.
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Lawal, Kamoru Abiodun. "Understanding the variability and predictability of seasonal climates over West and Southern Africa using climate models." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16556.
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Includes bibliographical referencesA good understanding of seasonal climate and the limit to which it can be predicted is crucial in addressing various socio-economic challenges in Africa. However, how to improve the capability of the dynamical models of the climate system in reproducing the regional seasonal climate variability and in replicating the role of various atmospheric circulation anomalies on the regional variability remains a major challenge. Thus far, understanding of seasonal climate over these regions, as well as the ability of climate models to predict them, has focused on the agreement of simulations of dynamical models of the climate system, rather than considering outliers as potentially vital contributors to understanding and predictability. This thesis uses discrepancy in a large ensemble of climate simulations as a tool to investigate variability in dominant seasonal rainfall and temperature patterns (i.e. classes) over West and Southern Africa, to examine the capability of climate models in reproducing the variability, and to study the predictability of the seasonal climates over South Africa. The dominant classes of variability (of rainfall and maximum temperature fields) in both regions are examined based on the Self-Organizing Map (SOM) classifications. The sequences in which each class occurs cannot be linked simply to a single common index of global scale atmospheric circulation anomalies, implying that the chaotic regional atmospheric circulations that modulate the global scale modes of variability are indispensable. The climate model examined adequately reproduces the dominant classes of seasonal climate over West and Southern Africa.