Improved Oceanic Cool-Skin Corrections Using a Refined Solar Penetration Model

Abstract

The oceanic near-surface temperature profile must be accurately characterized to enable precise determination of air?sea heat exchange and satellite retrievals of sea surface temperature. An improved solar transmission parameterization is integrated into existing models for the oceanic warm layer and cool skin within the Tropical Ocean and Global Atmosphere Coupled Ocean?Atmosphere Response Experiment (TOGA COARE) bulk flux model to improve the accuracy of predictions of the temperature profile and corresponding heat flux components. Application of the revised bulk flux model to data from 12 diverse cruises demonstrates that the improved parameterization results in significant changes to the predicted cool-skin effect and latent heat fluxes at low wind speeds with high solar radiation due to reduced absorption of solar radiation just below the surface. Daytime skin-layer cooling is predicted to increase by 0.03 K on average but by more than 0.25 K for winds below 1 m s?1 and surface irradiance exceeding 900 W m?2. Predicted changes to the warm-layer correction were smaller but exceeded 0.1 K below 1 m s?1. Average latent and sensible heat fluxes changed by 1 W m?2, but the latent flux decreased by 5 W m?2 near winds of 0.5 m s?1 and surface irradiance of 950 W m?2. Comparison with direct observations of skin-layer cooling demonstrated, in particular, that use of the improved solar transmission model resulted in the reduction of previous systematic overestimates of diurnal skin-layer warming. Similar results can be achieved using a simplified treatment of solar absorption with an appropriate estimate of the fraction of incident solar radiation absorbed within the skin layer.