Implications of Satellite OH Observations for Middle Atmospheric H 2 O and Ozone

Abstract

Satellite observations by the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI) have produced global measurements of hydroxyl (OH) in the atmosphere. These observations reveal a sharp peak in OH density near an altitude of 65 to 70 km and are thus consistent with observations from the Halogen Occultation Experiment (HALOE) on the NASA Upper Atmosphere Research Satellite (UARS), which showed an unexplained H ₂ O layer at the same level. Analysis of stratopause (about 50 kilometers) OH measurements and coincident ozone observations from the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment reveals that the catalytic loss of ozone attributable to odd-hydrogen chemistry is less than that predicted with standard chemistry. Thus, the dominant portion of the ozone deficit problem in standard models is a consequence of overestimation of the OH density in the upper stratosphere and lower mesosphere.