FIRSC measurements of cirrus during CRYSTAL-FACE

The FIRSC (Far Infrared Sensor for Cirrus) Fourier transform spectrometer was part of the cirrus remote sensing payload onboard the Proteus high altitude aircraft during the CRYSTAL-FACE campaign in July 2002. FIRSC measures submillimeter and far-infrared upwelling radiation from the Earth and the scattering effects of this radiation due to cirrus clouds below the aircraft. This technique is particularly sensitive to ice water path and particle size for large particles and thick cirrus. Cirrus parameters retrieved from measurements made during CRYSTAL-FACE are presented here. Comparisons are made with other remote sensing instruments on the same platform and with other aircraft and ground instruments for co-incident air masses.