The main objective of the microwave radiometer (MWR) on board ERS-1 and ERS-2 was the measurement of the integrated atmospheric water vapour column and cloud liquid water content, as correction terms for the signal of the radar altimeter (RA) on board the satellites.

In addition, MWR measurement data were useful for the determination of surface emissivity and soil moisture over land, for surface energy budget investigations to support atmospheric studies, and for ice characterisation.

The ERS-1 mission ended on 10 March 2000 and MWR measurements were continued on board the ERS-2 satellite which was retired on 5 September 2011.