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June 4, 2024 - 10:00 am
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School of Meteorology (Defense)Thesis Defense
Examining the Characteristics and Evolution of Temperature Whiplash Events in the US Southern Plains
Katie Giannakopoulos
Tuesday, June 4th, 2024
NWC 5600 | 10:00 AM
If unable to attend in person:
https://oklahoma.zoom.us/j/92547506259?pwd=85Nv1rLbAxDmHpbdIPaVNy5i2V6vb3.1
Meeting ID: 925 4750 6259
Passcode: 22202516
Abstract: Rapid extreme temperature swings, termed “temperature whiplashes”, can lead to significant and intense socioeconomic impacts. Few studies have considered temperature whiplashes over global, continental, or other large domains. These analyses suggest that certain locations within the domain may experience greater temperature swings, one being the United States Southern Plains. By selecting a specific area and considering temperature whiplashes on a regional scale, skillful, long-lead prediction and mitigation of these events may be improved. This study focuses on defining and characterizing temperature whiplash events in the Southern Plains region of the United States, specifically during the winter months (December-February). Two types of whiplashes are defined: the hot-to-cold and cold-to-hot. Using the ERA-5 dataset from 1950-2023, the Temperature Swing Index, defined as the standard deviation of the 24-hour difference filtered 6-hourly 2-meter temperature, is calculated and area-averaged across the Southern Plains. Days where the Temperature Swing Index exceeds the 90th percentile are termed “high swing days” (HSD). Temperature whiplash events are selected by examining each HSD, and considering the longevity and persistence of the overall temperature trend and the signs of the temperature anomalies up to 4 days before and after the HSD. This definition yields 45 anomalously hot-to-cold whiplash events and 14 cold-to-hot whiplash events. Composites of the geopotential height field at multiple pressure levels and lags illustrate large-scale atmospheric evolutions and key features that could enhance long-range prediction. Additionally, stratospheric-tropospheric interactions such as wave reflection are identified as a possible precursor to these events. By establishing the characteristics of temperature whiplash events and their precursors, there is the opportunity to improve predictions of these extreme events and determine how they may change in a changing climate.