Eastern U.S. Atmospheric River Types and Trends

Keywords: atmospheric rivers, eastern U.S., rainfall
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 03:40 PM (Eastern Time (US & Canada)) - 2/27/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 27

Abstract

Atmospheric rivers (ARs), driven by extratropical cyclogenesis, are the primary moisture transport forcing in the Western U.S. and principal producer of extreme precipitation events. A growing body of evidence suggests similar impacts for the Central and Eastern U.S. This study determines the leading modes of variability, or “types” of ARs in the Central and Eastern U.S. study domain through the implementation of a machine learning methodology. Self-organizing maps (SOMs) are leveraged to determine these ARs types, including an analysis of ARs during all months, and a subsequent analysis focusing on winter ARs. Additionally, trend analyses on the strength and size of ARs are produced to analyze changes to AR-driven integrated moisture transport over the 40-year study period. The SOMs confirm extratropical cyclones as the primary driver of ARs and the SOMs show coastal cyclones and lee-side cyclones as the producer of the strongest ARs. The trend analysis results suggest that mature cyclones, most notably Nor'easters and ARs rooted in the Gulf of Mexico, are transporting increasing amounts of moisture throughout the study period. Increasing moisture transport by mature cyclones across the Central and Eastern U.S. have important implications for flooding in highly populated corridors, including the Northeast U.S. and Mid-South. The results presented here show the types of ARs that drive increased precipitation in these regions. This study provides evidence that topography helps increase precipitation efficiency during certain AR types.