SAFIRE-A - Spectroscopy of the Atmosphere using Far-InfraRed mission /Airborne

A new instrument named SAFIRE-A (Spectroscopy of the Atmosphere using Far-Infrared Emission/Airborne),which can operate on high-altitude platforms, has been developed for the study of the atmospheric compositionthrough limb-scanning emission measurements. The instrument is a polarizing Fourier transform spectrometerthat operates in the far infrared with a resolution of 0.004 cm-1. SAFIRE-A uses efficient photon noise limiteddetectors and a novel optical configuration, which provide a cold pupil and field stop as well as cold narrowbandpass filters to enhance its sensitivity. The instrument was successfully operated on an M-55 stratosphericresearch aircraft in the polar regions during the winter 1996-97 Airborne Polar Experiment. The instrumentdesign, aircraft integration, and performances attained in the field campaign are described and discussed. Theatmospheric emission spectrum is measured with an rms noise accuracy of 0.5 K (measured in brightnesstemperature) in each spectral element near 20 cm-1 with a 30 s measurement time.