New results from CRISTA

Abstract

Trace gas distributions and temperatures in the mesosphere and lower thermosphere were derived from infrared spectra measured by the two CRISTA experiments flown in November 1994 and in August 1997. CRISTA (CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere) is a triple telescope cryogenically cooled infrared spectrometer which senses the Earth limb from a Shuttle orbit. The geographical coverage was -57°/+68° and -74°/+74° during the two missions, respectively. Each mission lasted slightly more than one week. The mesospheric set of trace gases include ozone, carbon dioxide and carbon monoxide, methane, water vapor, and atomic oxygen. In addition temperatures and pressures are obtained from the CO2 15 μm band. The temperature/pressure results are used to derive geostrophic wind fields. Most of the data reduction required non-LTE modelling of the radiation properties of the species. Practically all data exhibit considerable large scale structures in both latitude and longitude due to planetary waves or interhemispheric transport.