In the context of satellite remote sensing, “hyper-spectral” is a generic term that means that “many channels” are observed. For InfraRed (IR) instruments, this term is associated with thousands channels, but for the MicroWave (MW) domain, an instrument with hundred of channels is already considered to be hyper-spectral. There are two main alternative concepts in using hyper-spectral information in MW:
1. Hyper-spectral observations can consist in observing given absorption bands with a very high spectral resolution. The current operational MW instruments only provide observations in a few channels in each absorption band, and a continuous sampling within those bands with much finer spectral resolution deserves investigation. Following the ESA instructions, it is this concept that has been examined here.
2. Hyper-spectral observations can also be interpreted as a continuous sweep of a large frequency domain. In the MW, it could mean systematic observations from 20 to 800 GHz, with a spectral resolution of the order of 1 GHz. This option has not been considered in this study, following the ESA instructions. However, its interest for the scientific community will be discussed in the perspectives section.