Impacts of the Diurnal Cycle of Radiation on Tropical Cyclone Intensification and Structure

To investigate the impacts of the diurnal cycle on tropical cyclones (TCs), a set of idealized simulations were conducted by specifying different radiation (i.e., nighttime-only, daytime-only, full diurnal cycle). It was found that, for an initially weak storm, it developed faster during nighttime than daytime. The impacts of radiation were not only on TC intensification, but also on TC structure and size. The nighttime storm tended to have a larger size than its daytime counterparts. During nighttime, the radiative cooling steepened the lapse rate and thus reduced the static stability in cloudy regions, enhancing convection. Diabatic heating associated with outer convection induced boundary layer inflows, which led to outward expansion of tangential winds and thus increased the storm size.