Discovery of a Water Vapor Layer in the Arctic Summer Mesosphere: Implications for Polar Mesospheric Clouds
NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
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We report the discovery of a layer of enhanced water vapor in the Arctic summer mesosphere that was made utilizing two new techniques for remotely determining water vapor abundances. The first utilizes Middle Atmosphere High Resolution Spectrograph Investigation MAHRSI OH measurements as a proxy for water vapor. The second is a reanalysis of Halogen Occultation Experiment HALOE water vapor data with a technique to simultaneously determine polar mesospheric cloud PMC ice particle extinction along with the water vapor abundance. These results reveal a narrow layer of enhanced water vapor centered between 82-84 km altitude and coincident with PMCs, that exhibits water vapor mixing ratios of 10-15 ppmv. This indicates that a higher degree of supersaturation is present in the PMC region, and that PMCs are thus more efficient at sequestering total water both ice particles and vapor within the layer, than previously believed.
- Atmospheric Physics