Precipitation regime change in Western North America: The role of Atmospheric Rivers.

Gershunov, A., T.M. Shulgina, R.E.S. Clemesha, K. Guirguis, D.W. Pierce, M.D. Dettinger, D.A. Lavers, D.R. Cayan, S.D. Polade, J. Kalansky and F.M. Ralph, 2019: Precipitation regime change in Western North America: The role of Atmospheric RiversNature Scientific Reports, 9:9944, DOI:10.1038/s41598-019-46169-w.

Here, we explain the dominant mechanism for projected intensification of extreme precipitation in California and Western North America as part of the changing precipitation regime of this region. We have known about the decreasing frequency of precipitation in all Mediterranean climate regions as they become more subtropical and the increasing intensity of precipitation (especially in California) from previous work. In this latest study, we identify the dominant mechanism by which heavy precipitation becomes more extreme. The results are not necessarily surprising as other studies have suggested intensification of atmospheric rivers (ARs) in a warming climate, but we have now explicitly linked this intensification of ARs to changes in finely-resolved precipitation. This more mechanistic understanding of the intensification of heavy precipitation gives us a better handle on interpreting ongoing changes and planning for managing water resources and flood risk in a progressively more volatile future. 

The paper can be accessed online here. A press release about this work was issued by Scripps Institution of Oceanography. 

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