Evidence of non-LTE effects in mesospheric water vapor from spectrally-resolved emissions observed by CIRRIS-1A

Evidence of non-LTE effects in mesospheric water vapor as determined by infrared spectral emission measurements taken from the space shuttle is reported. A cryogenic Michelson interferometer in the CIRRIS-1A shuttle payload yielded high quality atmospheric infrared spectra. These measurements demonstrate the enhanced daytime emissions of H2O (020-->010) which are the result of non-LTE processes and in agreement with non-LTE models. The radiance ratios of H2O (010-->000) and (020-->010) Q(1) transitions during daytime are compared with non-LTE model calculations to assess the vibration-to-vibration exchange rate between H2O and O-2 in the mesosphere. An exchange rate of 1.2x10(-12) cm(3) s(-1) is derived.