MHS instrumentation

The Microwave Humidity Sounder (MHS) instrument is a compact five-channel self-calibrating microwave rotating radiometer weighing around 63 kg. Occupying a 0.8-metre cube, it is positioned on the nadir-facing side of the MetOp satellite and is designed to scan perpendicular to the direction flight (across track) at a rate of 2.67 seconds per scan. The swath width of the scan is approximately +/- 50°. The scan is synchronised with the AMSU-A1 and A2 instruments, with MHS performing three scan cycles for every one performed by the AMSU instruments.

The MHS incorporates four receiver chains at 89 GHz, 157 GHz and 190 GHz, with the 183 GHz data sampled in two discrete bands to provide the five channels. The separation of the four target frequencies is achieved by quasi-optical elements integrated in the received subsystem.