Advanced microwave sounding unit

For NOAA-18 (NOAA N), launched May 20, 2005, AMSU-B was replaced by a similar instrument, the Microwave Humidity Sounder (MHS).

Versions of AMSU-A also fly on the NASA Aqua Earth science satellite and the EUMETSAT MetOp series.

On these spacecraft, AMSU-B is replaced by similar microwave humidity sounders: HSB for Aqua and MHS for MetOp.

The next generation in the family is the Advanced Technology Microwave Sounder (ATMS), first flown on Suomi-NPP in 2011 and now standard equipment on the JPSS series of satellites, the first of which, NOAA-20, launched in 2017.

In the case of Metops and EOS Aqua this results in their crossing the equator at the same two local solar times every orbit.

It then makes observations of a warm calibration target and of cold space before it returns to its original position for the start of the next scan.

AMSU-B, with five channels between 89 and 183.3 GHz, has a spatial resolution near nadir of 15 km and is primarily intended for moisture sounding.

The EOS AMSU-A is part of a closely coupled triplet of instruments that include the AIRS and HSB.