Global distribution and seasonal dependence of satellite‐based whitecap fraction

We present the first study of global seasonal distributions of whitecap fraction, W , obtained from satellite‐based radiometric observations. Satellite‐based W incorporates variability from forcings other than wind speed and can capture differences in W in initial and late lifetime stages. The satellite‐based W is more uniform latitudinally than predictions from a widely used wind speed‐dependent parameterization, W ( U 10 ), formulated from in situ observations, being on average higher than the W ( U 10 ) predictions at low latitudes and lower at middle and high latitudes. This difference provides an explanation for the consistent geographical biases in sea spray aerosol concentration found in a number of large‐scale models. Satellite estimates of W would benefit air‐sea interaction and remote sensing applications that use parameterizations in terms of W such as sea spray flux, gas transfer, and surface winds.