The Advanced Microwave Sounding Unit-A (AMSU-A) is a 15-channel microwave sounder designed primarily to obtain temperature profiles in the upper atmosphere (especially the stratosphere) and to provide a cloud-filtering capability for tropospheric temperature observations. 

AMSU-A1 and AMSU-A2 along with the Atmospheric Infra-Red Sounder (AIRS) and the Humidity Sensor for Brazil (HSB) instruments collectively form the AIRS Project Instrument Suite aboard NASA’s Aqua platform that provides 3D measurements of temperature and water vapor through the atmospheric column along with measurements of atmospheric trace gases and surface and cloud properties.