Comparison of Odin-OSIRIS OH A2∑+-X 2Π 0-0 mesospheric observations and ACE-FTS water vapor observations

Abstract

[1] As the production of hydroxyl (OH) in the mesosphere is driven by solar photodissociation of water vapor, the OH vertical profile is thus influenced by the water vapor profile. The details of this coupling are investigated by using experimental water vapor profiles observed by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument as input to a photochemical model to predict OH profiles for comparison with experimental OH profiles observed by the Optical Spectrograph and Infra-Red Imager System (OSIRIS) instrument. We show that the model OH profiles in the 60 km to 80 km altitude region employing standard reaction rates are in agreement within 15% with the experimental OH profiles over a range of longitudes and local times, whereas the MAHRSI observations indicate the model OH densities in the middle mesosphere are approximately 30% too large. The quality of the OSIRIS OH observations and the ACE-FTS water vapor observations are both sufficiently accurate in the upper mesosphere to yield satisfactory agreement for individual profile comparisons. An example of the hemispheric maps of OH density measured by OSIRIS is shown for an altitude of 80 km. Copyright 2006 by the American Geophysical Union.