THE DETECTION OF THE HYDROXYL NIGHTGLOW LAYER IN THE MESOSPHERE BY ISAMS UARS/

Measurements of night-time radiance near 4.6 mu m by the ISAMS instrum ent on board the UARS satellite exhibit an enhancement in the upper me sosphere. We show in this work that this increase around 85 km tangent height is due to the OH (9-8) and OH (8-7) Meinel bands. The ISAMS da tabase therefore contains valuable information on the variability over a seasonal cycle of the OH high vibrational populations from which th e chemical heating of the upper mesosphere can be derived.