Assessing snow melt conditions is another use. Tracking sea ice distribution and conditions is a prime oceanographic application. Another marine use is for assessing sea surface temperature. Passive microwave sensors are important components on some meteorological satellites, being well suited to obtain temperature profiles through the atmosphere, as well as water vapor and ozone distributions and precipitation conditions. We describe the ESMR and SMMR scanning microwave radiometers flown on Nimbus metsats described on page 14-4 .
Open water appears in gray-green tones.
Several other satellites, e.g., TRMM, that use passive microwave to learn more about meteorological conditions are discussed on page 14-5 . It can measure such variables as wind velocity, soil moisture, and rainfall. One of its prime functions, useful for both military and civilian needs, is to monitor sea ice, much in the manner of the ESMR discussed above. Use this as a framework to follow ice variations in the Arctic in a temporal animation at this Norwegian Web site . I uses several of its channels to determine brightness temperatures over land and sea.