A new improved Louis surface flux parameterization scheme has been developed at the Naval Research Lab (NRL) that is expected to implement in the Navy’s operational mesoscale model (COAMPS). This new parameterization, run in offline mode, is tested against the COARE2.6 parameterization developed by Fairall and Bradley group and the direct flux observations from TOGA COARE, respectively. The results show that it significantly improves the behavior of Louis scheme under the low wind regime. It also takes consideration on the different roughness length for momentum and scalars. Modifications for the stable regime are also made.

The new scheme is further tested in this work using a variety of data sources, including those from the pilot measurements of the Coupled Boundary Layer Air Sea Transfer (CBLAST) in the summer of 2001. The data were selected to ensure the wide range of stability factor and wind speed over water. The original Louis scheme and the COARE2.6 parameterization are also included in this comparison. In addition, the sensitivity of turbulent fluxes to the settings of scalar roughness length is also examined.