Type of Document Thesis Author Stevens, Kelly Ann Author's Email Address firstname.lastname@example.org URN etd-12132007-112937 Title Statistical associations between large scale climate oscillations and mesoscale surface meteorological variability in the Apalachicola-Chattahoochee-Flint River Basin Degree Master of Science Department Meteorology, Department of Advisory Committee
Advisor Name Title Dr. Paul Ruscher Committee Chair Dr. Henry Fuelberg Committee Member Dr. Jon Ahlquist Committee Member Keywords
Date of Defense 2007-11-13 Availability unrestricted AbstractThe “water wars” of the Apalachicola-Chattahoochee-Flint (ACF) River Basin are fueled largely by historic and current droughts in the southeastern United States. In attempts to describe climatological circumstances that could lead to low flows in the ACF, this study examines relationships between some available surface climatological variables connected to evapotranspiration and four climatic oscillations using canonical correlation analysis (CCA).
The surface meteorological variables for the dependent data set include monthly values of maximum and minimum temperature, as well as precipitation, extracted from the National Climatic Data Center (NCDC) and the Parameter-elevation Regressions on Independent Slopes Model (PRISM) data sets for four climate divisions in the ACF. The precipitation data are used to compute standardized precipitation index (SPI) values for three, six, twelve, and twenty-four month periods (SPI3, SPI6, SPI12, SPI24) for 1901-2000. The oscillations chosen based upon their previously researched associations to climate patterns in the southeastern United States include the global scale Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Southern Oscillation Index (SOI). We apply analysis thresholds to the canonical loadings and cross loadings for the canonical roots extracted at the 95% significance level to display the relational results for two separate tests conducted using CCA.
The dependent data set for one test consists of the temperature data and SPI6, while the independent data set consists of all the indices for four seasons, allowing for time-lagged and concurrent relationship discoveries. In this test, the standardized temperature data account for much of the variance explained for the CCA-derived concocted variate, with the strongest canonical relationships occurring during the winter season (DJF). Precipitation appears in the wetter spring (MAM) and summer (JJA) season with an indirect relationship to SOI (spring) and PDO (summer). The climate indices with intra-annual frequencies tend to show inverse relationships with temperature throughout the year. The second test utilizes only the four intervals of SPI values for the dependent variable set to focus on precipitation variability at different time scales for the northernmost and southernmost sub-basin areas. The variations of precipitation in the Apalachicola sub-basin (southernmost) results are most sensitive to the SOI in the winter and spring seasons, where a significant relationship is found with the standardized precipitation indices with the higher variance (SPI3 and SPI6). Quite differently, the Upper Chattahoochee sub-basin results largely consist of indirect relationships between the climate oscillations with longer frequencies (AMO and PDO) with the longest time averaged SPI variable (SPI24). These findings reveal that weather and climate patterns in the ACF are not heterogeneous, and that multiple scales and multiple indices appear to be required to develop a comprehensive understanding of the nature of drought in this region.
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