First retrieval of cloud phase from SCIAMACHY spectra around 1.6 μm

Abstract An index for fast thermodynamic cloud phase retrievals, the cloud phase index (CPI), is presented. The index is calculated by fitting the spectral slope of the reflectance around 1.6 μm. It is normalized with the reflectance at 1.64 μm in order to make the index insensitive to calibration constants. A selected set of observations by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), an instrument on board the ENVISAT platform, is used. Preliminary results are encouraging, showing a positive index between ≈25 and 50 for ice clouds.