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Does increasing horizontal resolution improve the simulation of intense tropical rainfall?
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  • Akshaya C Nikumbh,
  • Pu Lin,
  • David Paynter,
  • Yi Ming
Akshaya C Nikumbh
Princeton Universitysity

Corresponding Author:[email protected]

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Pu Lin
Princeton University
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David Paynter
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Yi Ming
Boston College
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We examine tropical rainfall from Geophysical Fluid Dynamics Laboratory’s Atmosphere Model version 4 (GFDL AM4) at three horizontal resolutions of 100 km, 50 km, and 25 km. The model produces more intense rainfall at finer resolutions, but a large discrepancy still exists between the simulated and the observed frequency distribution. We use a theoretical precipitation scaling diagnostic to examine the frequency distribution of the simulated rainfall. The scaling accurately produces the frequency distribution at moderate-to-high intensity (≥10 mm day-1). Intense tropical rainfall at finer resolutions is produced primarily from the increased contribution of resolved precipitation and enhanced updrafts. The model becomes more sensitive to the grid-scale updrafts than local thermodynamics at high rain rates as the contribution from the resolved precipitation increases. On the contrary, the observed tropical precipitation extremes do not show a strong sensitivity to the grid-scale updrafts.
15 Oct 2023Submitted to ESS Open Archive
17 Oct 2023Published in ESS Open Archive