FORUM sensitivity to surface emissivity

FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) is a satellite mission selected in 2019 as the ninth ESA (European Space Agency) Earth Explorer mission. FORUM will provide interfer- ometric measurements in the spectral interval encompassing the Far-InfraRed (FIR) part of the spectrum, responsible for about 50% of the outgoing longwave ux lost by our planet into space. While more accu- rate measurements of the Top Of the Atmosphere (TOA) resolved spectrum in the FIR are necessary for reducing uncertainty in climate models, existing instruments are insucient. The observations will also improve the knowledge of several atmospheric variables, such as water vapor in the upper troposphere - lower stratosphere region, ice cloud properties and especially surface emissivity in the FIR, the focus of this seminar. In particular, I will present the results of our recent study of FORUM sensitivity in measuring surface emissivity in both clear and cloudy sky conditions, focusing on dierent aspects of the computational pipeline. Of particular interest are procedures for the injection of data from the ERA5 database, that is the fth generation ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis for the global climate and weather, and Bayesian techniques for deriving a-priori estimates from the MODIS (Moderate Resolution Imaging Spectroradiometer) database. Finally, I will conclude by dis- cussing extensions of the current surface emissivity database to IASI-NG (Infrared Atmospheric Sounding Interferometer New Generation) frequency range.