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Signature of the Contemporary Southwestern North American Megadrought in Mesopause Region Wave Activity
  • Chester S. Gardner,
  • Chiao-Yao She
Chester S. Gardner
University of Illinois at Urbana Champaign

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Chiao-Yao She
Colorado State University
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The Southwestern North American (SWNA) megadrought began in 2000 and is now believed to be the driest 22-year period in the region since at least 800 CE. The precipitation deficit during the megadrought (8.3% during 2000-2021) has been accompanied by a significant decrease in gravity waves observed in the upper atmosphere. Prior to the drought (1990-2000), wave-driven temperature fluctuation variances, between 85 and 100 km at Albuquerque and Ft. Collins, were comparable (62.2 K2 and 60.5 K2, respectively), with the largest variances occurring during winter and summer storm seasons. During the first decade of the drought (2001-2010), wave activity above Ft. Collins decreased by 28%, mostly above 94 km, and changed from primarily semiannual to primarily annual variations. These changes may be related to reduced wave generation by tropospheric storms during the megadrought and to an altered geographic distribution of precipitation events in the western and mid-western United States.