The Advanced Microwave Sounding Unit (AMSU) is an instrument that flies aboard several satellites. It is a radiometer that looks at the microwave spectrum. Its primary goal is to perform atmospheric sounding measurements of the atmosphere and return brightness temperature and moisture levels.
AMSU instruments are flown by both NASA and NOAA on several meteorological satellites:
The AMSU instruments aboard Aqua and MetOp work closely with AIRS and MHS respectively to produce several blended Level 2 geophysical data products.