Special Sensor Microwave Imager Sounder
|Within Vocab||SeaVoX Device Catalogue|
|Preferred Label||Special Sensor Microwave Imager Sounder|
|Definition||The Special Sensor Microwave Imager Sounder (SSMI/S) is a passive microwave radiometer that is an enhanced version of the The Special Sensor Microwave Imager (SSM/I). It measures atmospheric, oceanic and terrestrial microwave brightness temperatures from 19 to 183 GHz, from which ocean surface wind speed, atmospheric water vapour, cloud liquid water and rain rate can be derived. The SSMI/S is an enhanced version of the SSM/I. It consists of an offset 24-inch parabolic reflector fed by a corrugated, broad-band, seven-port horn antenna. The reflector and feed are mounted on a drum that contains the radiometers, digital data subsystem, mechanical scanning subsystem, and power subsystem. The reflector-feed-drum assembly is rotated about the axis of the drum by a coaxially mounted bearing and power transfer assembly (BAPTA). All data, commands, timing and telemetry signals, and power pass through the BAPTA on slip ring connectors to the rotating assembly.The absolute brightness temperature of the scene incident upon the antenna is received and spatially filtered by the antenna to produce an effective input signal or antenna temperature at the input of the feed horn antenna. The feedhorn data are input to the receiver subsystem where frequency multiplexing occurs to produce 24 channels of data. The receiver outputs are converted to the video spectrum, digitized and formatted. The SSMI/S has 24 channels and eight frequencies. It measures the same frequencies and polarisations as the SSM/I, with the exception of the 85.5 GHz channel which has been replaced by a 91.655 GHz channel. A 183 GHz channel has also been added. The instrument rotates continuously about an axis parallel to the local spacecraft at 31.6 rpm and measures the upwelling scene brightness temperature over an angular range of 143.2 degrees at nadir. It has a swath width of approximately 1700 kilometres. Frequency multiplexing occurs as the main reflector is illuminated by six broadband corrugated feedhorns, grouping Channels 1-5; Channels 6, 7, 19-24; Channels 12-14; Channels 15-16; Channels 8-11; and Channels 17-18. Flown on F16, F17, F18, F19. https://nsidc.org/data/docs/daac/ssmis_instrument/|
|Has Current Version||http://vocab.nerc.ac.uk/collection/L22/current/TOOL1053/3/|
|Authored On||2017-08-10 12:25:4|
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