MSX measurements of BTH and ATH gravity waves and ATH polar mesospheric clouds

A major goal of the Midcourse Space Experiment (MSX) sponsored by the Ballistic Missile Defense Organization (BMDO) was to generate database of terrestrial and atmospheric background scenes to aid in the development and evaluation of infrared surveillance systems. The SPIRIT III cryogenic sensor aboard the MSX satellite, designed and built by the Space Dynamics Laboratory of Utah State University, collected infrared (IR) data from over 200 measurements of terrestrial and atmospheric backgrounds in 1996 and 1997. One-third of the events viewed below-the-horizon (BTH) terrestrial scenes only in the mid-wave infrared (MWIR) since the long wave infrared (LWIR) channels saturated, and the remainder events looked above-the-horizon (ATH), primarily at limb altitudes up to 200 km. The bulk of the IR data is from the SPIRIT III radiometer, with lesser amounts from the SPIRIT III interferometer. The capability of SPIRIT III to make measurements over a broad dynamic range of spectral and radiometric sensitivities with signal to noise above 100 has enabled observations of atmospheric structure in the MWIR from cloud and cloud-free regions and from thunderstorm sources, auroral enhancements, polar mesospheric clouds, and IR airglow layers and is enabling the derivation of global radiance statistics for limb and terrestrial backgrounds. In this report we review selected results from the analysis of this important database.