An overview of the COAMPS-TC system applied during HFIP and T-PARC

The newly developed Coupled Ocean/Atmosphere Mesoscale Prediction System – Tropical Cyclone (COAMPS®-TC) designed to predict tropical cyclone track, structure and intensity has been applied in real time in support of the THORPEX Pacific Asian Regional Campaign (T-PARC) and the ONR Tropical Cyclone Structure-08 (TCS08) experiments, as well as the recent Hurricane Forecast Improvement Project (HFIP) in the Atlantic for the 2009 season. For these real time tests, COAMPS-TC system was configured with three nested grids with 45, 15, 5 km horizontal resolution, with the inner two most meshes moving with the tropical cyclone center. Statistical verification indicates that the COAMPS-TC system provided skillful track forecasts competitive with other limited area and global models. However, some systematic biases were apparent in the intensity forecasts, particularly during TCS08. A new version of COAMPS-TC recently has been evaluated using the TCS08 and HFIP datasets. This new COAMPS-TC version includes a new shallow cumulus parameterization and improvements to a number of model components including the vertical diffusion, surface flux, and boundary layer parameterizations. The new version of COAMPS-TC shows considerable improvements in the structure and intensity forecasts for both the W. Pacific and Atlantic basins, on par with other statistical and dynamical models for forecast lead times out to 48 h. An update on recent sensitivity tests of the TC track and intensity forecasts to aspects of the model physics and lateral boundary conditions will be presented as well.