The Sensitivity of Eyewall Replacement Cycles to Shortwave Radiation

The sensitivity of tropical cyclone secondary eyewall formation (SEF) and subsequent eyewall replacement cycles (ERCs) to shortwave radiation is examined in this study by varying the solar constant and diurnal cycle at different times prior to an ERC using idealized simulations from the Weather Research and Forecasting model. The magnitude of shortwave radiation plays an important role in modifying the timing of the SEF with nonlinear interactions amplifying the SEF formation differences at longer lead-times. Shortwave radiation has a delaying effect on the SEF and ERC primarily through its modifications of the distribution of convective and stratiform heating profiles in the rainbands. Shortwave radiation reduces both the area and diabatic heating of convection in the model domain, while increasing the amount of stratiform precipitation that has weaker low-level cooling and upper-level heating rates. The primary mechanism by which shortwave radiation reduces the diabatic heating profile and frequency of convection in the rainbands is through heating of the mid-upper troposphere which stabilizes the region and reduces convective available potential energy.