Assessing the climate-scale variability of atmospheric rivers affecting western North America

TitleAssessing the climate-scale variability of atmospheric rivers affecting western North America
Publication TypeJournal Article
Year of Publication2017
AuthorsGershunov A, Shulgina T, F. Ralph M, Lavers DA, Rutz JJ
JournalGeophysical Research Letters
Date Published2017/08
ISBN Number1944-8007
Keywords1840 Hydrometeorology; 1854 Precipitation; 3305 Climate change and variability; 3339 Ocean/atmosphere interactions; 4313 Extreme events; Climate variability; detection of atmospheric rivers; extreme orographic precipitation; hydroclimate; integrated vapor transport; western North America
Abstract

A new method for automatic detection of atmospheric rivers (ARs) is developed and applied to an atmospheric reanalysis, yielding an extensive catalog of ARs land-falling along the west coast of North America during 1948–2017. This catalog provides a large array of variables that can be used to examine AR cases and their climate-scale variability in exceptional detail. The new record of AR activity, as presented, validated and examined here, provides a perspective on the seasonal cycle and the interannual-interdecadal variability of AR activity affecting the hydroclimate of western North America. Importantly, AR intensity does not exactly follow the climatological pattern of AR frequency. Strong links to hydroclimate are demonstrated using a high-resolution precipitation data set. We describe the seasonal progression of AR activity and diagnose linkages with climate variability expressed in Pacific sea surface temperatures, revealing links to Pacific decadal variability, recent regional anomalies, as well as a generally rising trend in land-falling AR activity. The latter trend is consistent with a long-term increase in vapor transport from the warming North Pacific onto the North American continent. The new catalog provides unprecedented opportunities to study the climate-scale behavior and predictability of ARs affecting western North America.

DOI10.1002/2017GL074175
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