Evaluation of COAMPS™ Real Time Forecast for CBLAST-Low Summer Experiments 2002/2003

For two consecutive years (2002 and 2003), Navy’s COAMPS has been used to provide real-time forecasts for CBLAST-Low field experiments in the Northeast coastal area. This real-time effort has four objectives: (1) providing weather information to CBLAST scientists for mission planning; (2) providing surface forcing for Rutgers University’s ocean model to perform the ocean forecast over the region; (3) evaluating the COAMPS model; and (4) studying the coastal boundary layer and air-sea interaction. During the intensive observational periods, COAMPS produced 60 hour forecasts every 12 hours on a three grid-nest (3, 9, and 27 km) configuration. To evaluate the turbulence mixing parameterizations both in the boundary layer and at the surface, we have compared the predicted mean and turbulence structures with the measurements from a variety of observational platforms operated in CBLAST IOPs. The comparison shows that the predicted boundary layer is generally warmer than the observed, likely due to the higher sea surface temperature used in the model. COAMPS consistently and successfully predicted sea/land breeze and their transitions, which may lead to significant regime change of the marine boundary layer due to the impacts of marine and continental air mass. A direct comparison between the modeled and observation derived surface fluxes shows that both the sensible and latent fluxes are significantly overestimated. It results likely because the sea surface temperature used in the model is generally higher than the observed. When using the observed sea surface temperature and mean variables, COAMPS surface flux parameterization produces considerably improved fluxes. Therefore, sea surface temperature field is a focus in order to improve COAMPS simulations of marine boundary layer structure.