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Constraining and Characterizing the size of Atmospheric Rivers: A perspective independent from the detection algorithm.
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  • Héctor Alejandro Inda Díaz,
  • Travis Allen O'Brien,
  • Yang Zhou,
  • William D. Collins
Héctor Alejandro Inda Díaz
University of California Davis, University of California Davis

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Travis Allen O'Brien
Indiana University Bloomington, Indiana University Bloomington
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Yang Zhou
Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory
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William D. Collins
Lawrence Berkeley National Lab, Lawrence Berkeley National Lab
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Atmospheric rivers (AR) are large and narrow filaments of poleward horizontal water vapor transport. Because of its direct relationship with horizontal vapor transport, extreme precipitation, and overall AR impacts over land, the AR size is an important characteristic that needs to be better understood. Current AR detection and tracking algorithms have resulted in large uncertainty in estimating AR sizes, with areas varying over several orders of magnitude among different detection methods. We develop and implement five independent size estimation methods to characterize the size of ARs that make landfall over the west coast of North America in the 1980-2017 period and reduce the range of size estimation from ARTMIP. ARs that originate in the Northwest Pacific (WP) (100$^\circ$E-180$^\circ$E) have larger sizes and are more zonally oriented than those from the Northeast Pacific (EP) (180$^\circ$E-240$^\circ$E). ARs become smaller through their life cycle, mainly due to reductions in their width. They also become more meridionally oriented towards the end of their life cycle. Overall, the size estimation methods proposed in this work provide a range of AR areas (between 7x10$^{11}$m$^2$ and 10$^{13}$ m$^2$) that is several orders of magnitude narrower than current methods estimation. This methodology can provide statistical constraints in size and geometry for the AR detection and tracking algorithms; and an objective insight for future studies about AR size changes under different climate scenarios.
27 Aug 2021Published in Journal of Geophysical Research: Atmospheres volume 126 issue 16. 10.1029/2020JD033746