TABLE OF CONTENTS In 1978 the Scanning Multichannel Microwave Radiometer (SMMR) was launched on the U.S. satellite Nimbus-7. SMMR represented a new and very successful concept: the multifrequency passive imager that has played a dominating role within remote sensing of the Earth's surface. SMMR measured the two polarizations of the brightness temperature from the Earth at the frequencies: 6.6, 10.69, 18.0, 21.0, 37.0 GHz. It used a 25 conical reciprocating scan with an incidence angle on the ground of 50 . The antenna aperture was 79 cm and the footprints were: 79 121, 49 74, 29 44, 25 38, 14 21 (FPS FPL in kilometers) [1].
Data from the SMMR has been widely used through the years and the established applications are in Table 13.1.
| Ocean parameters | Sea surface temperature |
| Wind speed | |
| Atmospheric parameters | Water vapor |
| Liquid water | |
| Rain intensity | |
| Cryopheric parameters | Sea ice (fractional ice coverage, ice boundary, ice type classification) |
| Perennial snow (on ice caps and glaciers) | |
| Seasonal snow (area, water equivalent, water runoff) | |
| Land parameters | Permafrost |
| Soil moisture | |
| Vegetation characteristics |
The life of SMMR came to an end in 1987 (many years after the anticipated date) and replacements or upgrades were studied by the space agencies. In 1979/1980 the ESA Imaging Microwave Radiometer (IMR) was studied [2]. It employed the frequencies of 6.84, 10.65, 15.3, 23.8, 36.5, and 90 GHz and a 1.26-m aperture. Thus, it was basically an upgraded version of...
