Microwave sounding of earth covers at the frequencies near 118.75 GHz oxygen line

The basic characteristic of terrestrial covers obtained by remote sounding is the brightness temperature. The brightness temperature is a sum of its self-radiation and atmospheric thermal radiation scattered on a cover. In a millimeter wavelength range, and especially in its short-wave part, temporal variations of both components are comparable to natural contrasts of various types of covers. The radio thermal imagine of a terrain is less stable, than it is in more long-wave spectral ranges. More stable characteristic of a cover is emissivity ore albedo. The two-frequency technique is proposed to enhance the stability of millimeter wave picture of terrain. The technique also makes it possible to estimate both albedo and thermodynamic temperatures of the earth cover. The polarimeter operating on several frequencies near the oxygen line 118,75 GHz have been developed to realize the technique. The measurement results show great potential method using atmospheric spectral features to increase informative facility for remote sensing of terrestrial surface in the millimeter wavelength range.