climatology of single-day rapid drought cessation events in the southwestern United States
Emily Pearl Harris
University of West Florida,
Master of Science (MS), University of West Florida
2019
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Abstract
Drought is a common and important component of the hydroclimatology of the southwestern USA. However, less attention has been paid to drought termination in the region, especially Rapid Drought Cessation Events (RDCEs). Here, the "Southwest" was defined by drought region using Principal Components Analysis (PCA) of the annual average Palmer Drought Severity Index (PDSI) for all NOAA state climate divisions in the U.S.A. For the Southwest, 765 droughts occurred between 1895 to 2017; 575 (6.2%) of these droughts ended abruptly (for one month's time). Furthermore, 54 (0.6%) of those RDCEs occurred in a single-day. The majority of RDCEs, and single-day RDCEs, occurred in the cool season. Droughts of short (<1 months) and long (>76months) duration were ended by single-day RDCEs. Similarly, RDCEs ended droughts of varying severity, the extreme being a -5.68 (PDSI; November 1951). While there is no significant trend when SD-RDCEs occur, the results showed that most occur in the winter season and most occurring in Arizona. Analyses are in progress to identify the storm type responsible for every occurrence of RDCE and describe the spatiotemporal properties of RDCE and associated storm type.