The dual channel METEOSAT radiometer

A high-resolution dual-channel radiometer is described which will constitute the main payload of the European METEOSAT and provide a full-time cloud and earth mapping capability with a ground resolution of about 5 km on the IR channel and 2.5 km on the optical channel. Development of the instrument is briefly outlined, and detailed descriptions are presented of the scanning process, thermal channel, optical system, and electronics packages. The thermal channel is capable of measuring the radiance of cold clouds and hot ground with a noise equivalent temperature difference no greater than 0.4 K for an image at 300 K or 1.2 K at 200 K. A proposed water vapor channel is described which will replace one optical channel at night and whose data will be multiplexed with the optical channel outputs.