Comparison of the Nimbus-4 BUV ozone data with the Ames two-dimensional model

A comparison is made of the first two years of Nimbus-4 backscattered ultraviolet (BUV) ozone measurements with the predictions of the Ames two-dimensional model. The ozone observations used in this study consist of the mixing ratio on the 1-, 2-, 5-, and 10-mb pressure surfaces. These data are zone and time averaged to obtain seasonal means for 1970 and 1971 and are found to show strong and repeatable meridional and seasonal dependencies. The model used for comparison with the observations extends from 80°N to 80°S latitude and from altitudes of 0 to 60 km with 5° horizontal grid spacing and 2.5-km vertical grid spacing. The chemical reaction and photolysis rate constants used in the model are those recommended in the report of the NASA Panel for Data Evaluation (1979) Chemical reaction and photolysis rates are diurnally averaged, and the photodissociation rates are corrected for the effects of scattering.It is found that the large altitude, latitude, and seasonal changes in the ozone data agree well with the model predictions. Also shown are model predictions of the sensitivity of the comparisons to changes in the assumed mixing ratios of water vapor, odd nitrogen, and odd chlorine, as well as to changes in the ambient temperature and transport parameters.