CLOUDS - A cloud, arerosol, radiation and precipitation explorer

The CLOUDS study defines a small satellite addressing the objective of cloud-radiation interaction monitoring for improved climate and weather prediction. The study was funded by the EC, and now various paths are explored to provide study continuation and eventual programme implementation. Only passive radiometers are included, covering the spectral range from UV to MW, with more polarisations and viewing geometries. There are six instruments, four (the optical ones) integrated into a single package, one in MW, one in Sub-mm waves. All instruments have conical scanning, with fore- and aft- views; one has multi-angle capability. The resolution is 5 or 10 or 40 km depending on the instrument, and the observing cycle is 24 h for measurement from TIR or MW, or 48 h for measurements which involve channels operating with solar radiation. Sizing parameters of CLOUDS are: mass ∼ 900 kg, power ∼ 1.6 kW, data rate 1.1 Mbps for direct read-out in S-band, 30 Mbps for global data in X-band, volume compatible with launch by Eurockot.