Recent Developments to the COAMPS-TC Dynamic Initialization Schemes

The accurate and balanced initialization of tropical cyclones (TCs) in mesoscale numerical weather prediction (NWP) models remains a great challenge. Imbalances in the initial condition can manifest in rapid adjustments leading to large short term (0-48 h) intensity errors. In order to improve TC initialization, dynamic initialization schemes have been developed for the U. S. Navy's Coupled-Ocean Atmosphere Mesoscale Prediction System-Tropical Cyclones (COAMPS-TC). These schemes include: (i) a tropical cyclone dynamic initialization scheme (TCDI), where the TC vortex is spun-up in a quiescent environment and inserted into the model initial fields (after removal of the existing vortex), (ii) a full-model dynamic initialization (DI) scheme, where the forecast model is run forward with full-physics, but relaxed to the analyses' horizontal momentum during the initialization period, and (iii) a TCDI/DI scheme, which combines the first two schemes, and (iv) the DI scheme with the addition of prescribed heating in order to improve the TC secondary circulation. Testing of these schemes is conducted on a sample of TCs from 2011-2014 in comparison to a static initialization scheme. It is demonstrated that the dynamic initialization schemes have improved initial vortex structure and balance, and reduced short-term intensity errors.