Advanced microwave sounding unit

From Glossary of Meteorology



Advanced Microwave Sounding Unit

The Advanced Microwave Sounding Unit (AMSU) instrument suite consists of AMSU-A and AMSU-B. The primary function of the AMSUs is to obtain temperature and water vapor in the troposphere and stratosphere. The first AMSU was launched on 13 May 1998, on board the National Oceanic and Atmospheric Administration's (NOAA's) NOAA-15 Polar-Orbiting Operational Environmental Satellite (POES), and the last one was launch on NOAA-19 (6 February 2009). For actual characteristics of each AMSU on NOAA-15 through NOAA-19, see the NOAA KLM Users Guide (section 3.3, 3.4 and Appendix D).

AMSU-A is a 15-channel microwave sounder designed primarily to obtain temperature profiles in the troposphere and stratosphere. Each AMSU-A instrument is composed of two separate units: AMSU-A2 with 2 channels at 23.8 and 31.4 GHz and AMSU-A1 with 12 channels in the range of 50.3–57.3 GHz plus 1 channel at 89.0 GHz. AMSU-A1 has a set of 12 oxygen band channels (3–14) for retrieving the atmospheric temperature profile from the Earth's surface to about 50 km in altitude. Precipitation, sea ice, snow cover, surface emissivity, atmospheric liquid water, and total precipitable water are derived primarily from three window channels (23.8 and 31.4 GHz from AMSU-A2 and 89.0 GHz from AMSU-A1).

AMSU-B, later called the Microwave Humidity Sounder (MHS) measures five microwave channels and accompanies AMSU-A: one channel in the 89-GHz "window" channel, one channel at 150 GHz, and remaining three channels around the 183-GHz water vapor line. The primary function of AMSU-B (MHS) is to obtain the water vapor profile in the troposphere and lower stratosphere.

Term edited 10 August 2021.