NOTE: As of October 2011, the AMSR-E instrument on board the Aqua satellite stopped producing data due to a problem with the rotation of its antenna.
The Advanced Microwave Scanning Radiometer (AMSR-E), onboard NASA's Earth Observation Satellite (EOS) Aqua and launched in May of 2002, is a conically scanning, dual-polarized microwave radiometer that detects faint microwave emissions from the Earth's surface and atmosphere at 12 channels and 6 frequencies ranging from 6.9 to 89.0 GHz. Horizontally and vertically polarized radiation are measured separately at each frequency (Kawanishi et al., 2003 and wwwghcc.msfc.nasa.gov/AMSR/instrument_descrip.html).
The AMSR-E rotates continuously about an axis parallel to the local spacecraft vertical at 40 revolutions per minute (rpm). At an altitude of 705 km, it measures the upwelling scene brightness temperatures over an angular sector of ±61 degrees about the sub-satellite track, resulting in a swath width of 1445 km. During a period of 1.5 seconds the spacecraft sub-satellite point travels 10 km. Even though the instantaneous field-of-view for each channel is different, active scene measurements are recorded at equal intervals of 10 km (5 km for the 89 GHz channels) along the scan. The half cone angle at which the reflector is fixed is 47.4° that results in an Earth incidence angle of 55.0°. Table 2.1 lists the pertinent performance characteristics.
Various geophysical parameters can be retrieved from AMSR-E, including water vapor, cloud liquid water, precipitation, sea surface temperature, sea surface wind speed, sea ice concentration, snow water equivalent, and soil moisture. Global and continuous observation is performed with fine spatial resolution by using one of the largest ever microwave radiometer antenna. The long-term geophysical record will play an important role in climate change monitoring and will provide valuable information for understanding the Earth's climate system, including water and energy circulation. Near real-time products will be used to investigate satellite data assimilation into weather forecasting models and to contribute to improved forecasting accuracy. The 10.65 GHz frequency data is used in the SCR algorithm for soil moisture retrieval.