A Comparison of Bulk Aerodynamic Methods for Calculating Air-Sea Flux
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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The Louis et al. 1982 bulk aerodynamic method for air-sea flux estimates is currently used in mesoscale models such as COAMPS, while the TOGA-COARE method is a state of the art flux parameterization involving recent findings in surface layer meteorology, and has been proposed as a replacement to Louis. The Louis and TOGA-COARE methods were compared to direct observations daring ACE-1. Results from both methods compared well to observations for momentum flux. For sensible and latent heat flux, both methods showed good agreement in low flux regimes and underestimated the fluxes at higher values. Calculation of the transfer coefficients required to match observations indicated that the bulk transfer coefficients do not increase rapidly enough for zL values less than -0.5. In the high wind regime, the transfer coefficients were very sensitive to static stability. The COARE method was superior to the Louis method for sensible heat flux estimates while the Louis method was better for latent heat flux. A sensitivity test was done to use the COARE roughness length parameterization in the Louis method. This resulted in slight improvement in sensible heat flux estimates for highly convective conditions. Latent heat flux was overestimated by the modified Louis parameterization in the same manner as the COARE algorithm, indicating that specification of the latent heat roughness length requires further study.
- Atmospheric Physics