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Investigating Changes in Tropical Cyclone Rainfall in Aquaplanet Simulations Under Idealized Warming

Presentation Date
Monday, December 14, 2020 at 5:34am
Location
Virtual
Authors

Author

Abstract

The estimated rate at which climate change increases rainfall within tropical cyclones (TCs) has a wide range of uncertainty. Previous studies using various methods have found rates both below and greatly above the theoretical Clausius-Clapeyron rate of ~6-7% per degree of warming. This study utilizes an idealized model to further explore the potential changes in TC rainfall due to climate change. Specifically, the Community Atmosphere Model version 5, the atmospheric component of the Community Earth System Model, is run at high-resolution using an aquaplanet configuration with uniform thermodynamic forcing following the Radiative Convective Equilibrium Model Intercomparison Program protocols, but with Earth’s rotation rate. This essentially creates a “global tropics” experimental setup with each simulation having a specified sea surface temperature (SST) that is uniform over the global domain. These experimental SSTs span the range of 295K to 305K, which approximates the SST range measured under TCs in real-world observations. The idealized model setup provides a simplified setting to study TCs without the effects of wind shear, land, and varying SSTs, and similar setups have been used previously to examine the dynamic controls of TC genesis and size. In addition to rainfall, other TC characteristics that may impact rainfall, such as genesis location, size, and intensity, will be compared among the simulations with different SSTs. Preliminary results show that while TC rainfall increases in simulations with warmer SSTs, the effect is complicated by changes in TC frequency, lifetime, intensity, and size.

Funding Program Area(s)