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Ocean Surface Flux Algorithm Effects on Tropical Indo-Pacific Intraseasonal Precipitation
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  • Chia-Wei Hsu,
  • Charlotte A. DeMott,
  • Mark Branson,
  • Jack Reeves Eyre,
  • Xubin Zeng
Chia-Wei Hsu
Colorado State University

Corresponding Author:[email protected]

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Charlotte A. DeMott
Colorado State University
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Mark Branson
Colorado State University
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Jack Reeves Eyre
University of Washington
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Xubin Zeng
The University of Arizona
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Surface latent heat fluxes help maintain tropical intraseasonal precipitation. We develop a latent heat flux diagnostic that depicts how latent heat fluxes vary with the near-surface specific humidity vertical gradient (dq) and surface wind speed (|V|). Compared to fluxes estimated from |V| and dq measured at tropical moorings and the COARE3.0 algorithm, tropical latent heat fluxes in the NCAR CEMS2 and DOE E3SMv1 models are significantly overestimated at |V| and dq extrema. Madden–Julian oscillation (MJO) sensitivity to surface flux algorithm is tested with offline and inline flux corrections. The offline correction adjusts model output fluxes toward mooring-estimated fluxes; the inline correction replaces the original bulk flux algorithm with the COARE3.0 algorithm in atmosphere-only simulations of each model. Both corrections reduce the latent heat flux feedback to intraseasonal precipitation, in better agreement with observations, suggesting that model-simulated fluxes are overly supportive for maintaining MJO convection.
16 Apr 2022Published in Geophysical Research Letters volume 49 issue 7. 10.1029/2021GL096968