Developing a drought climatology for Delaware (1948-2005)

Date
2012
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University of Delaware
Abstract
Drought index (Palmer Drought Severity Index and Standardized Precipitation Index), precipitation, and streamgage data were used in the development of a drought climatology for Delaware based on the period 1948 to 2005. Twelve meteorological droughts were identified during the study period, eleven of which resulted in concurrent hydrological droughts. Analysis of drought index and precipitation data revealed that meteorological drought is, on average, more severe in northern Delaware than in coastal and southern regions of the state. Through the analysis of the 500hPa height anomalies present during each respective drought, several synoptic patterns were found to be associated with the onset, duration, and termination of droughts in Delaware. Chi-square tests were used to determine if statistically significant relationships exist between incidence of drought in Delaware and variations in the Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), El NiƱo Southern Oscillation (ENSO), and Pacific North American Teleconnection Pattern (PNA). A statistically significant relationship was found between drought occurrence and the combined effect of the PDO and AMO; prolonged drought events during the study period were found to occur when both the PDO and AMO were positive, or when PDO was in its positive phase and AMO negative in its negative phase.
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