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Full-Text Articles in Physical Sciences and Mathematics
Identification Of Long Term Changes And Evaluation Of The Relationships Among Streamflow Variability And Oceanic-Atmospheric Indices, Soumya Sagarika
Identification Of Long Term Changes And Evaluation Of The Relationships Among Streamflow Variability And Oceanic-Atmospheric Indices, Soumya Sagarika
UNLV Theses, Dissertations, Professional Papers, and Capstones
To examine the effects of climate variability on streamflow, this thesis presents a comprehensive analysis of the streamflow variability of the continental United States and its association with oceanic-atmospheric indices. First, the presence of trends with consideration of short term and long term persistence followed by shifts over the past years in the continental U.S. streamflow were analyzed by using the non-parametric tests: Mann Kendall and Pettitt. Second, the spatio-temporal relationships between seasonal streamflow variability of continental U.S. and sea surface temperatures (SST) and 500 mbar geopotential height (Z500) of the Pacific and Atlantic were established using the singular valued …
Impacts Of Climate Changes On The Spatiotemporal Distribution Of Precipitation In The Western United States, Peng Jiang
Impacts Of Climate Changes On The Spatiotemporal Distribution Of Precipitation In The Western United States, Peng Jiang
UNLV Theses, Dissertations, Professional Papers, and Capstones
Precipitation in the Intermountain West is characterized by its great variability in both spatial and temporal distributions. Moreover, the spatiotemporal distribution of the precipitation is changing due to the climate changes. In this dissertation, three studies are conducted to investigate the multi-scale temporal variability of precipitation, the performance of current climate models on this variability, the influence of large-scale ocean oscillations on heavy precipitation, and the impact of human induced global warming on storm properties.
The first study is to examine the performance of current climate models on the simulation of the multi-scale temporal variability determined from the observed station …
Estimating Annual Precipitation For The Colorado River Basin Using Oceanic-Atmospheric Oscillations, Ajay Kalra, Sajjad Ahmad
Estimating Annual Precipitation For The Colorado River Basin Using Oceanic-Atmospheric Oscillations, Ajay Kalra, Sajjad Ahmad
Civil and Environmental Engineering and Construction Faculty Research
Estimating long-lead time precipitation under the stress of increased climatic variability is a challenging task in the field of hydrology. A modified Support Vector Machine (SVM) based framework is proposed to estimate annual precipitation using oceanic-atmospheric oscillations. Oceanic-atmospheric oscillations, consisting of Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Niño–Southern Oscillation (ENSO) for a period of 1900–2008, are used to generate annual precipitation estimates with a 1 year lead time. The SVM model is applied to 17 climate divisions encompassing the Colorado River Basin in the western United States. The overall results revealed that …
Evaluating Changes And Estimating Seasonal Precipitation For Colorado River Basin Using Stochastic Non-Parametric Disaggregation Technique, Ajay Kalra, Sajjad Ahmad
Evaluating Changes And Estimating Seasonal Precipitation For Colorado River Basin Using Stochastic Non-Parametric Disaggregation Technique, Ajay Kalra, Sajjad Ahmad
Civil and Environmental Engineering and Construction Faculty Research
Precipitation estimation is an important and challenging task in hydrology because of high variability and changing climate. This research involves (1) analyzing changes (trend and step) in seasonal precipitation and (2) estimating seasonal precipitation by disaggregating water year precipitation using a k-nearest neighbor (KNN) nonparametric technique for 29 climate divisions encompassing the Colorado River Basin. Water year precipitation data from 1900 to 2008 are subdivided into four seasons (i.e., autumn, winter, spring, and summer). Two statistical tests (Mann-Kendall and Spearman’s rho) are used to evaluate trend changes, and a rank sum test is used to identify the step change in …
Association Of Oceanic-Atmospheric Oscillations And Hydroclimatic Variables In The Colorado River Basin, Ajay Kalra
Association Of Oceanic-Atmospheric Oscillations And Hydroclimatic Variables In The Colorado River Basin, Ajay Kalra
UNLV Theses, Dissertations, Professional Papers, and Capstones
With increasing evidence of climatic variability, there is a need to improve forecast for hydroclimatic variables i.e., precipitation and streamflow preserving their spatial and temporal variability. Climatologists have identified different oceanic-atmospheric oscillations that seem to influence the behavior of these variables and in turn can be used to extend the forecast lead time. In the absence of a good physical understanding of the linkages between oceanic-atmospheric oscillations and hydrological processes, it is difficult to construct a physical model. An attractive alternative to physically based models are the Artificial Intelligence (AI) type models, also referred to as machine learning or data-driven …
Using Oceanic-Atmospheric Oscillations For Long Lead Time Streamflow Forecasting, Ajay Kalra, Sajjad Ahmad
Using Oceanic-Atmospheric Oscillations For Long Lead Time Streamflow Forecasting, Ajay Kalra, Sajjad Ahmad
Civil and Environmental Engineering and Construction Faculty Research
We present a data-driven model, Support Vector Machine (SVM), for long lead time streamflow forecasting using oceanic-atmospheric oscillations. The SVM is based on statistical learning theory that uses a hypothesis space of linear functions based on Kernel approach and has been used to predict a quantity forward in time on the basis of training from past data. The strength of SVM lies in minimizing the empirical classification error and maximizing the geometric margin by solving inverse problem. The SVM model is applied to three gages, i.e., Cisco, Green River, and Lees Ferry in the Upper Colorado River Basin in the …