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Tropical Cyclones and Equatorial Waves in a Convection-Permitting Aquaplanet Simulation with Off-Equatorial SST Maximum
  • Rosimar Rios-Berrios,
  • Christopher A Davis,
  • Jonathan Martinez
Rosimar Rios-Berrios

Corresponding Author:[email protected]

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Christopher A Davis
National Center for Atmospheric Research, P.O. Box 3000, 3450 Mitchell Lane, Boulder, Colorado 80307
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Jonathan Martinez
National Hurricane Center
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Tropical cyclogenesis can be influenced by convectively coupled equatorial waves; yet, existing datasets prevent a complete analysis of the multi-scale processes governing both tropical cyclones (TCs) and equatorial waves. This study introduces a convection-permitting aquaplanet simulation that can be used as a laboratory to study TCs, equatorial waves, and their interactions. The simulation was produced with the Model for Prediction Across Scales-Atmosphere (MPAS-A) using a variable resolution mesh with convection-permitting resolution (i.e., 3-km cell spacing) between 10oS–30oN. The underlying sea-surface temperature is given by a zonally symmetric profile with a peak at 10oN, which allows for the formation of TCs. A comparison between the simulation and satellite, reanalysis, and airborne dropsonde data is presented to determine the realism of the simulated phenomena. The simulation captures a realistic TC intensity distribution, including major hurricanes, but their lifetime maximum intensities may be limited by the stronger vertical wind shear in the simulation compared to the observed tropical Pacific region. The simulation also captures convectively coupled equatorial waves, including Kelvin waves and easterly waves. Despite the idealization of the aquaplanet setup, the simulated three-dimensional structure of both groups of waves is consistent with their observed structure as deduced from satellite and reanalysis data. Easterly waves, however, have peak rotation and meridional winds at a slightly higher altitude than in the reanalysis. Future studies may use this simulation to understand how convectively coupled equatorial waves influence the multi-scale processes leading to tropical cyclogenesis.
15 May 2023Submitted to ESS Open Archive
25 May 2023Published in ESS Open Archive