Recent improvements to NRL's mesoscale modeling system

The Naval Research Laboratory (NRL) recently has added a number of new capabilities to the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) to enable more accurate analysis and prediction of the atmosphere and ocean at high-resolution. An overview of several of these new development efforts targeted for the atmospheric module of COAMPS will be highlighted in this presentation. The NRL Atmospheric Variational Data Assimilation System (NAVDAS) is a 3DVar analysis system that has been developed for global data assimilation and prediction using NOGAPS, and more recently for mesoscale data assimilation applications using COAMPS. The results indicate that COAMPS using NAVDAS with a 6-h incremental update cycle shows a significant improvement in the analysis and prediction of temperature and moisture relative to a multivariate optimum interpolation system. The Weather Research and Forecasting (WRF) model physical parameterizations software has been integrated in a modular manner into COAMPS to enable seamless access to the NCEP and NCAR WRF parameterization suites. The modular physics package gives COAMPS a diverse set of parameterization options available for deterministic or ensemble model applications. A generalized input/output software interface is now under development to enable the COAMPS and WRF modeling systems to be tested using identical initial and boundary conditions. Recent improvements to the COAMPS physical parameterization suite include implementation of the NOAH/WRF land surface model and an urban model. Several modifications have been made to the surface flux parameterization over the ocean in order to improve the representation of air-sea transfer for the low-wind and high-wind regimes based on the recent Coupled Boundary Layers Air-Sea Transfer (CBLAST) field campaigns. Results will be shown that describe the positive impact on forecast skill associated with the more accurate representation of these surface processes. For high-resolution applications, COAMPS has also been recently extended to perform in a Large Eddy Simulation (LES) mode. Results will be summarized from the COAMPS-LES system, which includes a new anelastic pressure solver and new physics modules, for a range of cloud-topped boundary layer flows.