Why Does the Initial Wind Profile Inside the Radius of Maximum Wind Matter to Tropical Cyclone Development?

This study examines the possible dependence of tropical cyclone (TC) development on the initial winds inside the radius of maximum wind (RMW) through ensemble axisymmetric numerical simulations. Results demonstrate that the vortex with higher initial winds inside the RMW favor larger surface enthalpy flux and thus faster moistening and earlier convective organization in the inner core, significantly shortening the initial spinup period. Higher inertial stability associated with higher winds inside the RMW implies higher eyewall-heating efficiency, giving rise to higher intensification rate in the subsequent intensification stage but little difference in the steady-state intensity. The results are confirmed with several sensitivity experiments using different model parameters and three-dimensional simulations using the same model and configuration. The findings from this study strongly suggest that the realistic representation of the initial inner-core winds is key to skillful TC intensity forecasts by numerical models and routine high-resolution observations of the inner-core wind structure are urged for improving TC intensity forecasts.