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The Response of Tropical Cyclone Inner Core and Outer Rainband Precipitation to Warming in Idealized Convection-Permitting WRF
  • Alyssa M. Stansfield,
  • Kristen Rasmussen
Alyssa M. Stansfield
The University of Utah

Corresponding Author:[email protected]

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Kristen Rasmussen
Colorado State University
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Abstract

Global mean and extreme tropical cyclone (TC) precipitation has been increasing and is expected to continue to increase into the future due to climate change. While climate models project that precipitation will increase mainly in the TC inner core, data from satellite observations show a decrease in mean TC inner core precipitation over time and an increase in the outer rainbands since 1998. This work uses convection-permitting Weather Research and Forecasting (WRF) model simulations to investigate if this discrepancy between models and observations is related to coarse model resolutions used in past studies. The simulations are idealized, with single TCs initialized from weak vortices over domain-constant sea surface temperatures (SSTs). In these simulations, TC intensity and inner core precipitation greatly increase with SST warming while outer rainband precipitation increases slightly. More of the inner core is occupied by convection more frequently in the warmer simulations, while the convective activity remains constant with warming in the TC outer region. Mixing ratios of hydrometeors and cloud ice increase with warming in both the inner core and outer rainbands, while the TCs’ vertical circulations deepen and mean upward velocities strengthen. Results suggest that even convection-permitting models do not capture a decrease in TC inner core precipitation with warming, albeit in an idealized model set-up. This work demonstrates how analysis of three-dimensional storm mode structures can provide insight into processes that change TC precipitation in different regions of the storm, and future work will include applying this analysis to more realistic convection-permitting simulations.
14 Aug 2024Submitted to ESS Open Archive
15 Aug 2024Published in ESS Open Archive