Remote sensing of cirrus cloud microphysical properties using spectral measurements over the full range of their thermal emission

The thermal emission of cirrus clouds, spectrally-resolved in the 100–1400 cm − 1 range (100–7.1 μm), has been modeled and compared with measurements performed during two field campaigns from the ground-based site of Testa Grigia on the Italian Alps at 3480 m of altitude. The analysis of cirrus microphysics, through spectral fitting, shows the importance of using also the far infrared portion of the emitted spectrum at wavenumbers below the 667 cm − 1 carbon dioxide absorption band, where only a few measurements exist because of the high opacity of the atmosphere caused by the strong water vapor absorption. The resulted distribution of the fitted cloud parameters is in good agreement with the typical statistical distribution of the midlatitude cirrus cloud parameters.