Recorded presentation5.5
Global drought in the second half of the twentieth century
Konstantinos Andreadis, Univ. of Washington, Seattle, WA; and J. Sheffield, E. Wood, and D. Lettenmaier
Although droughts are among the costliest of natural disasters, relatively little is known about their space-time characteristics, and how they have changed in the recent past – particularly in lesser developed parts of the world. Droughts can be characterized by their severity, duration, frequency, and spatial extent. Although past work has often used indices such as the Palmer Drought Severity Index (PDSI), which are based entirely on climatic indicators, the advent of land surface parameterizations (LSPs) provides a much stronger physical basis for understanding the nature of drought as represented by anomalies in soil moisture and runoff. We used a global gridded data set of soil moisture and runoff produced by the Variable Infiltration Capacity (VIC) LSP at one degree latitude-longitude spatial resolution to explore the characteristics of agricultural and hydrological drought over the last half of the 20th century. The hydrological state variables were simulated by the VIC LSP, driven by a hybrid meteorological forcing dataset that combines reanalysis fields with a suite of observations. Severity-Area-Duration (SAD) analysis was used to summarize the envelope of the most extreme global droughts over large space and time scales. Drought severities (calculated from soil moisture and runoff departures from a threshold percentile) for different areas and durations were used to construct an envelope SAD curve of the most severe drought events for different global regions. The variability of drought spatial extent and severity was also analyzed. In addition, we evaluated trends in drought characteristics, both globally and regionally. Finally, we performed an exploratory analysis of correlations of drought characteristics (for the most severe drought events) with precipitation and temperature, as well as climate signals (ENSO), in an effort to identify possible teleconnections between drought severity/duration with sea surface temperature. Recorded presentation
Session 5, Drought Assessment And Prediction
Tuesday, 22 January 2008, 1:30 PM-3:00 PM, 223
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