Mission objectives and instrument design concept of EarthCARE FTS

EarthCARE(Earth Clouds, Aerosol and Radiation Explorer) project is a candidate ofthe ESA(European Space Agency)Earth Explorer Core Missions. There are many uncertainties mainly caused by aerosols, clouds and their interactionwith radiation in predictions of climate change using numerical models. EarthCARE will provide vertical and horizontaldistributions and physical characteristics of clouds and aerosols, and also provide the Earth radiation budget. Earth-CARE is the joint proposal between ESA, National Space Development Agency of JAPAN (NASDA) and Communica-tions Research Laboratory (CRL). The Phase-A study is going on. The EarthCARE satellite has five sensors, CloudProfiling Radar (CPR), ATmospheric LIDar (ATLID), Multi-Spectral Imager (MSI), Broad Band Radiometer (BBR)and Fourier Transform Spectrometer (FTS).NASDA is studying FTS design. Main objective of EarthCARE FTS is to provide spectrally resolved outgoing radi-ance. This spectrum has many useful signatures from the surface/cloud/aerosol/water which can not get from spectrallyintegrated measurement. Another objective of EarthCARE FTS is to retrieve temperature and water vapor profiles inclear air and above the clouds. EarthCARE FTS is a compact Michelson interferometer, which covers from 5.6psn to25 tm with 0.5 cm' spectral resolution. The FOV(Field OfView) is 10km so that the data can be used in conjunctionwith BBR.Keywords: EarthCARE, FTS, fourier transform spectrometer, Infrared