Variability and trends in the OH airglow layer observed by GOMOS/ENVISAT

Abstract : The OH near-infrared nigthglow emission in the upper mesosphere is a marker of the chemistry and dynamics occurring at this level. The stellar occultation spectrometer GOMOS on board ENVISAT allowed to observe the OH(8-4) Meinel band in the spectral range 930-955 nm with a spectrometer dedicated to the observation of the water vapour. Climatology of OH emission has been established for the period 2002-2012. It allowed to confirm already published results as the maximum of intensity and semi-annual variation at the equator. The causes of variability and trends in the brightness and maximum altitude of the OH layer will be discussed. A new result concerns the apparent correlation of the emission rate with the solar activity.