Stability-Dependent Exchange Coefficients for Air-Sea Fluxes

摘要

This study introduces exchange coefficients for wind stress (C(sub D)), latent heat flux (C(sub L)), and sensible heat flux (C(sub S)) over the global ocean. They are obtained from the state-of-the-art Coupled Ocean- Atmosphere Response Experiment (COARE) bulk algorithm (version 3.0). Using the exchange coefficients from this bulk scheme, C(sub D), C(sub L), and C(sub s) are then expressed as simple polynomial functions of air-sea temperature difference (T(sub a)-T(sub s)) where air temperature (T(sub a)) is at 10 m, wind speed (V(sub a)) is at 10 m, and relative humidity (RH) is at the air-sea interface-to parameterize stability. The advantage of using polynomial based exchange coefficients is that they do not require any iterations for stability. In addition, they agree with results from the COARE algorithm but at approximately 5 times lower computation cost, an advantage that is particularly needed for ocean general circulation models (OGCMs) and climate models running at high horizontal resolution and short time steps. The effects of any water vapor flux in calculating the exchange coefficients are taken into account in the polynomial functions, a feature that is especially important at low wind speeds (e.g., V(sub a)).