Mid-course Space Experiment (MSX): capabilities of the LWIR interferometer for remote sensing of trace constituents in the stratosphere and mesosphere

The planned mid-course space experiment (MSX) observations will include two experiments for remote detection of atmospheric trace constituents above 10 km altitude, based on measurements of limb spectral radiance by the cryogenic IR interferometer and the ultraviolet and visible spectrographic imagers. The timing of the measurements is particularly advantageous since they will likely be the only regular limb observations of trace constituents during the operational lifetime of the MSX satellite. The SPIRIT III interferometer has a maximum spectral resolution of 1 cm -1 in six spectrally isolated channels whose vertical fields of view are between 4 and 13 km in line-of-sight tangent altitude. The six channels will provide spectra over wavelengths in the 2.6-28 micrometers range for tangent heights up to 180 km. The capabilities of the interferometer for the planned remote-sensing experiments, based on predicted instrument noise and saturation levels, are described in this paper.