The apparent temperature of the sea at microwave frequencies

A discussion of the apparent temperature of the sea at microwave frequencies is presented using a theory based on the Kirchhoff approximation for scattering from rough, finitely conducting surfaces. Detailed numerical results on the variation of the temperature with wind speed are discussed for a frequency of 19.4 GHz. The dependence of the rms slope of the sea on wind speed, which is needed in the theory, is based on experimental measurements. It is found that significant temperature changes occur with increasing wind speed for horizontally polarized radiation. The temperature of vertically polarized radiation is much less affected by the wind and, at an angle of
50\deg
(at 19.4 GHz), is almost independent of the state of the sea.