SSMI

SSMI stands for Special Sensor Microwave Imager, a family of passive microwave imagers carried on the Defense Meteorological Satellite Program (DMSP) satellites. The instrument provides global measurements of the Earth's surface and atmosphere by detecting microwave brightness temperatures at several frequencies. Because microwaves can penetrate clouds, SSMI data enable observations under all weather conditions and during day and night, supporting weather forecasting and climate research.

The instrument is a cross-track scanning radiometer with multiple microwave channels. The observations are used to derive geophysical parameters such as sea ice concentration, rainfall and snowfall over the oceans, ocean surface wind speeds, snow cover, soil moisture, and various land-surface properties. Over the oceans, the brightness temperatures correlate with wind speed, and specific channels help distinguish precipitation from cloud liquid water, improving interpretation in cloudy regions.

The SSMI program began in the late 20th century and has been implemented on successive DMSP satellites. In the 2000s a related instrument, SSMIS (Special Sensor Microwave Imager/Sounder), expanded the channel set and capabilities to provide enhanced observations and additional products. The SSMI data stream formed a long-running, widely used data record for meteorology, cryosphere monitoring, and climate research. Data are archived and disseminated by NOAA and partner organizations and are accessible for scientific analysis, assimilation into numerical weather prediction models, and climate monitoring.