Gravity-capillary curvature spectrum determined from the sea surface brightness temperature

Polarimetric measurements collected by microwave radiometers at several view angles and frequencies give an opportunity to convert the sea surface brightness temperatures to mean square slope of long waves and curvature spectral density in the gravity-capillary interval without a priori assumptions about the shape of spectrum. Such an inversion was made using radiometric data collected during Coastal Ocean Probe Experiment (COPE'95) from a blimp. It is shown that at low and moderate wind speed conditions typical for COPE'95 (4-7 m/s) the curvature spectrum has a maximum at wavenumber of about 4.5 rad/cm, slightly higher than the wavenumber of phase velocity minimum. The estimation of mean square slope of surface waves is very close to values of Cox and Munk model.