A climatology of atmospheric river interactions with the southeastern United States coastline

Abstract

Atmospheric rivers ( ARs ) are narrow and elongated bands of anomalous water vapour transport that have been widely studied due to their notable influence on regional weather patterns, surface hydrology, and the global water cycle. Although ARs produce a relatively large proportion of the annual precipitation in the southeastern quadrant of the United States, a detailed climatological analysis of Southeastern atmospheric rivers ( SE ‐ ARs ) has not been conducted. In this study, a climatology of SE‐AR coastal interactions from 1979 to 2014 was constructed from a global AR data set to examine the spatiotemporal characteristics of SE‐ARs as well as the importance of synoptic‐scale and low‐frequency modes of climate variability in modulating their frequency. The climatology revealed that SE‐ARs were most prevalent during the cold season, with the majority of these wintertime coastal interactions occurring predominately in the Gulf of Mexico. The synoptic‐scale and low‐frequency modes of climate variability favourable for SE‐AR development differed depending on the season and sub‐region of the Southeast considered. More specifically, a dipole effect was discovered, as conditions conducive for SE‐AR coastal interactions along the western Gulf generally inhibited SE‐AR interactions with the Florida Peninsula and vice versa. Overall, a better understanding of the seasonality of SE‐ARs as well as the synoptic‐scale and low‐frequency modes of climate variability that encourage their development could lead to improved forecasting and community awareness of the devastating AR ‐related flood events that occur throughout the Southeast.

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