Monday, 30 July 2001
A Comparison of Bulk Aerodynamic Methods for Calculating Air-sea Fluxes
The Louis flux parameterization as applied in the Navy’s Coupled Oceanic and Atmospheric Prediction System (COAMPS) is compared to the TOGA-COARE flux algorithm using observations collected during the Aerosol Characterization Experiment (ACE-1) 15 November 1995 to 15 December 1995. The Louis method is computationally very compact and works well for large-scale numerical forecast models. On the mesoscale, other Bulk methods have been proposed in order to improve the accuracy of the air-sea flux calculations to better depict local scale forcing. The TOGA-COARE flux algorithm is a state-of-the-art method incorporating several physical considerations neglected in earlier models. This method is specifically designed to produce more accurate flux estimates from bulk methods but is an iterative approach that is more computationally expensive.
These two methods were found to be extremely sensitive to accurate sea surface temperature (SST) measurements. The warm-layer correction algorithms incorporated in the TOGA-COARE method to adjust from Bulk SST to skin temperature were found to improve the resultant fluxes. The two Bulk methods showed close agreement with each other and with eddy correlation measurements of the actual fluxes for momentum flux. For latent and sensible heat flux, the two methods showed good agreement in low flux regimes but the Louis method underestimated the flux in weakly stable and highly convective environments.