AN INTERCOMPARISON OF MODEL OZONE DEFICITS IN THE UPPER-STRATOSPHERE AND MESOSPHERE FROM 2 DATA SETS

We have compared a diurnal photochemical model of ozone with nighttime data from the limb infrared monitor of the stratosphere (LIMS) and gr ound-based microwave observations. Consistent with previous studies, t he model underpredicts the observations by about 10-30%. This agreemen t is strong confirmation that the model ozone deficit is not simply an artifact of observational error since it is unlikely to occur for two completely different ozone data sets. We have also examined dhe seaso nal, altitudinal, and diurnal morphology of the ozone deficit. Both co mparisons show a deficit that peaks in the upper stratosphere (2-3 mba r) and goes through a minimum in the lower mesosphere from 1.0 to 0.4 mbar. At lower pressures (< 0.2 mbar) the deficit appears to increase again. The seasonal variation of the deficit is less consistent. The d eficit kith respect to the LIMS data is least in winter while with res pect to the microwave data, the deficit shows little seasonal variatio n. Finally, the night-to-day ratio in our model is iii generally good agreement with that seen in the microwave experiment. Increasing the r ate coefficient for the reaction O + O-2 + M --> O-3 + M improves the fit, while a very large (50%) decrease in the HOx catalytic cycle is n ot consistent with our observations. Increasing the atomic oxygen reco mbination rate also improves the overall agreement with both data sets ; however, a residual discrepancy still remains. There appears to be n o single chemical parameter which, when modified, can simultaneously r esolve both the stratospheric and mesospheric ozone deficits.