The Scanning Multichannel Microwave Radiometer (SMMR) operated on NASA's Nimbus-7 satellite for more than eight years, from 26 October 1978 to 20 August 1987, transmitting data every other day as part of NASA's Pathfinder Program. The SMMR was a ten channel instrument capable of receiving both horizontally and vertically polarized radiation, and delivered orthogonally polarized antenna temperature data. A combination of oval Instantaneous Fields of View (IFOVs) and the integration times of the radiometers yields roughly circular beam spots with the following diameters: 6.6 GHz at 148 km, 10.7 GHz at 91 km, 18 GHz at 55 km, 21 GHz at 46 km, and 37 GHz at 27 km.

The primary purpose of SMMR was to measure sea surface temperature and near-surface winds under all weather conditions for developing and testing global ocean circulation models and other aspects of ocean dynamics. Additional parameters were also measured using SMMR, such as winds, water vapor, liquid-water content, mean cloud droplet size, rainfall rate, and sea ice.

The National Snow and Ice Data Center (NSIDC) archives and distributes daily data products from SMMR. To obtain SMMR data, please refer to the Passive Microwave Sea Ice Products Web page.