6.2 A Re-analysis for the Observed Responses of Mesospheric H2O to Solar Cycle Forcings

Tuesday, 27 June 2017: 11:00 AM
Salon G-I (Marriott Portland Downtown Waterfront)
Ellis Remsberg, NASA/LaRC, Hampton, VA

This study reports on responses of mesospheric water vapor (H2O) to the 11-year variations of the 10.7-cm solar flux proxy. The re-analyses herein are for time series of H2O from the Halogen Occultation Experiment (HALOE) from June 1992 to November 2005, and they employ multiple linear regression (MLR) techniques. H2O responses are large and negative in the upper mesosphere at solar maximum, due to the enhanced flux at Lyman-α wavelength. There is an observed changeover to weaker, positive H2O responses for the middle and lower mesosphere, and there is good continuity for those responses across latitude and pressure-altitude. A positive response at solar maximum comes from enhancements of the uv-photolysis of molecular oxygen (O2) leading to increased production of ozone and O (1D), followed by the subsequent oxidation of methane (CH4) and production of H2O. Separate analyses verify that the responses of HALOE CH4 are negative at solar maximum in the lowermost mesosphere. The domain of positive H2O responses also exhibits asymmetry with latitude for the southern versus the northern hemispheres, most likely due to differences in the net transport across their domains. The associated H2O trends from the MLR analyses agree with independent determinations of their trends in the mesosphere from satellite and ground-based observations over 1992-2005.
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