The influence of non-wind based parameters on estimating the active and total whitecap coverage globally

Whitecap formation is dominantly driven by surface stress imparted to the ocean surface by the wind and is often parameterized using wind speed. Wind speed alone cannot explain the variance of the data. Recent efforts by Salisbury et al. (2013) identified some secondary parameters using PCA, but no functional forms were provided for estimating whitecap coverage. While PCA is a useful tool in understanding influential parameters, estimating whitecap coverage requires a functional form. This study determines the most important parameters to include in estimating whitecap coverage globally using a modified power law function,

W=a^(P)*u₁₀^b(P),

where W is the whitecap coverage, u₁₀ is the equivalent neutral wind at 10-m, and a and b are functions of a given parameter, P. Whitecap values and additional parameterizations come from the Windsat Whitecap Database (WWD).

The WWD, developed by Anguelova and Webster, provides microwave emissivity-based whitecap coverage from WindSat's 10 and 37 GHz channels. The Whitecap Database provides daily whitecap coverage on a 0.5° x 0.5° global grid with values representing the active and total whitecap coverage. Whitecap coverage is matched to the new QuikScat Level 2B Version 3 Winds, GDAS, and SSM/I winds. Additional parameterizations including SST, Tair, and currents are included in the database. The top preforming parameters are presented with functional forms.