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The Role of Radiative Interactions in Tropical Cyclone Development under Realistic Boundary Conditions

Presentation Date
Monday, December 14, 2020 at 8:34pm



The impact of radiative interactions on tropical cyclones (TCs) is investigated using a global, TC-permitting general circulation model (GCM) with realistic boundary conditions. In this model, synoptic-scale radiative interactions are suppressed by overwriting the model-generated atmospheric radiative cooling rates with its monthly-varying climatological values. When radiative interactions are suppressed, the global TC frequency is significantly reduced. This suggests that radiative interactions are a critical component of TC development even in the presence of spatially varying boundary conditions. The reduced TC activity is primarily due to a decrease in the frequency of pre-TC synoptic disturbances (“seeds”), whereas the background environment in which the seeds undergo cyclogenesis is less affected. This suggests that synoptic-scale radiative interactions primarily influence TC activity at the pre-genesis stage. When radiative interactions are suppressed, TC genesis shifts toward coastal regions, whereas TC lysis locations stay almost unchanged; together the distance between genesis and lysis is shortened, reducing TC duration. In a warmer climate, the magnitude of TC reduction due to suppressing radiative interactions is diminished due to the larger contribution from latent heat release in the moister climate. These results highlight the importance of radiative interactions in modulating the frequency and duration of TCs under realistic boundary conditions.

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