[A-AS02] Advances in Tropical Cyclone Research: Past, Present, and Future

[AAS02-16] Intensified Tropical Cyclones Simulations Employing a High-Wind Drag Relation over Sea Surface

*Wei Wei¹ (1.CMA Earth System Modeling and Prediction Centre)

Keywords: Surface drag relation, Tropical cyclones, Climate models

Accurate parametrization of momentum fluxes at high winds across the air–sea interface is crucial for realistically simulating the surface wind fields of tropical cyclones (TCs). Climate models often struggle to reproduce observed TC intensities, particularly surface wind speeds. This study evaluates the performance of a revised surface drag scheme with capping drag coefficient at high wind speeds in global climate models. Our results indicate that the revised surface drag scheme significantly improves the representation of TCs in a statistical sense: i) Not only the mature intensity but also the maximum 10-meter wind speeds throughout the TC lifecycle are largely enhanced; ii) Biases in the pressure–wind relationship are notably alleviated, exhibiting reasonable agreement with observations; and iii) Other TC statistical features, such as TC number, central sea level pressure, individual lifetime, and intensification rate show relatively minor sensitivity to the surface drag schemes. The main reason for the superiority of the revised high-wind drag relation is that the lower drag coefficient in high-wind conditions significantly increases the maximum potential intensity (MPI), indicating a higher theoretical limit for TC intensities. These findings are consistent across different model versions and resolutions, highlighting the robustness of the high-wind surface drag parameterization in controlling the simulated surface wind speeds of TCs.