Sensitivity of Quasi-Periodic Outer Rainband Activity of Tropical Cyclones to the Surface Entropy Flux

摘要

The influence of outer-core surface entropy fluxes(SEFs)on tropical cyclone(TC)outer rainband activity is investigated in this study with a fully compressible,nonhydrostatic model.A control simulation and two sensitivity experiments with the outer-core SEF artificially increased and decreased by 20%respectively were conducted to examine the quasi-periodic outer rainband behavior.Larger negative horizontal advection due to the greater radial wind and the positive contribution by asymmetric eddies leads to a longer period of outerrainband activity in the SEF-enhanced experiment.The well-developed outer rainbands in the control and SEF-reduced simulations significantly limit the TC intensity,whereas such an intensity suppression influence is not pronounced in the SEF-enhanced experiment.As diabatic heating in outer rainbands strengthens the outer-core tangential wind,the quasi-periodic activity of outer rainbands contributes to the quasi-periodic variations of the inner-core size of the TCs.