Recent Developments to the COAMPS-TC Dynamic Initialization Schemes

Prediction of tropical cyclone intensity and structure remains a great challenge. Tropical cyclone (TC) dynamic initialization schemes have been developed for the Navy's operational Coupled-Ocean Atmosphere Mesoscale Prediction System-Tropical Cyclones (COAMPS-TC). The suite of dynamic initialization schemes include: (i) the tropical cyclone dynamic initialization scheme (TCDI), where the TC vortex is spun-up in a quiescent environment and inserted into the model initial fields, (ii) the dynamic initialization (DI) scheme, where the forecast model is run with full-physics, but relaxed to the analyses' horizontal momentum during the additional initialization period, and (iii) the TCDI/DI scheme, which combines the first two schemes. Previous testing has shown the TCDI/DI scheme to be superior to the other two in intensity prediction.

Recent enhancements to the TCDI/DI scheme are described. The major enhancement is the utilization of the idealized version of COAMPS-TC for the vortex spin-up at high horizontal resolution (5-km), and the implementation of dynamic relaxation to user-specified intensity and radial wind structure. Verification of the performance of the new scheme on the prediction of track, size, and intensity is conducted on TCs in the North Atlantic basin. Then, the intensity and track verification is run on a larger sample of TCs, including other ocean basins. The new scheme is shown to have improved initial balance and improved prediction of TC intensity and size over the older scheme. Future plans for operational implementation will be discussed.