Sun, R., A. C. Subramanian, B. D. Cornuelle, M. R.
Mazloff, A. J. Miller, F. M. Ralph, H. Seo and I. Hoteit, 2021:
The role of air-sea interactions in Atmospheric Rivers:
Case studies using the SKRIPS regional
coupled model
Journal of Geophysical Research-Atmospheres, 126, e2020JD032885.
Abstract.
Atmospheric rivers (ARs) play a key role in California's water supply and are
responsible for most of the extreme precipitation and major
ooding along the west coast of
North America. Given the high societal impact, it is critical to improve our understanding
and prediction of ARs. This study uses a regional coupled ocean-atmosphere modeling
system to make hindcasts of ARs up to 14 days. The roles of air{sea interactions
in AR events are investigated by comparing coupled model hindcasts to hindcasts made
using persistent sea surface temperature (SST). Two groups of coupled runs are
highlighted in the comparison: (1) ARs occurring during times with strong SST cooling and
(2) ARs occurring during times with weak SST cooling. During the events with strong
SST cooling, the coupled model simulates strong upward air-sea heat
fluxes associated
with ARs; on the other hand, when the SST cooling is weak, the coupled model
simulates downward air-sea heat
fluxes in the AR region. Validation data shows that the
coupled model skillfully reproduces the evolving SST, as well as the surface turbulent heat
transfers between the ocean and atmosphere. To evaluate the
influence of the ocean on
ARs we analyze two representative variables of AR intensity, the vertically integrated
water vapor (IWV) and integrated vapor transport (IVT). During strong SST cooling
AR events the simulated IWV is improved by about 12% in the coupled run at lead times
greater than one week. For IVT, which is about twice more variable, the improvement
in the coupled run is about 5%.
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