13C.3 How Does the Diurnal Radiative Heating Cycle Impact the Genesis and Intensification of Tropical Cyclones?

Thursday, 19 April 2018: 11:00 AM
Champions ABC (Sawgrass Marriott)
James H. Ruppert Jr., Max Planck Institute for Meteorology, Hamburg, Germany

While prior studies have revealed the important impacts of interactive radiation and its diurnal cycle on tropical cyclones, a controlled assessment of the daily-mean impacts of the diurnal shortwave heating cycle has not been conducted. This issue is addressed here by conducting a set of convection–permitting numerical simulations using the radiative–convective equilibrium (RCE) framework with prescribed sea surface temperature (SST). Radiation and surface fluxes are calculated interactively in each simulation, with daily-mean shortwave heating unvaried, but with the diurnal cycle of shortwave heating switched either on or off. Analogous to simulations of non-rotating self-aggregation, a cyclone spontaneously develops from an initially homogeneous environment with randomly distributed deep convection, and intensifies due to feedbacks from cloud–radiation interaction and surface fluxes. The pronounced impact of diurnal shortwave heating on circulation and mean precipitation is described, while the daily-mean impact of the diurnal shortwave heating cycle on genesis and intensification is quantified.
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