Comparisons of satellite ozone data in the lower stratosphere for 1978/1979

Abstract

Lower stratospheric zonal mean ozone distributions are compared in both hemispheres from the Nimbus 7 Solar Backscattered Ultraviolet (SBUV) (version 5) and Limb Infrared Monitor of the Stratosphere (LIMS) data sets. Generally, there is very good agreement with regard to individual profile shape and magnitude and with their longitudinal variability about the zonal mean. When the data are considered in terms of Umkehr layer amounts, there are subtle but significant differences in the respective meridional ozone gradients and their variations with time. These differences do not seem to be related to SBUV diffuser plate drift effects because differences are not apparent in the upper stratosphere and because they are pronounced in late spring to summer of both hemispheres of the lower stratosphere. It appears more likely that the differences are related to a changing ozone optical depth (LIMS) and constraints to an assumed profile climatology in the retrieval (SBUV). Stratospheric Aerosol and Gas Experiment (SAGE) satellite ozone results are also presented for April 1979 at 10, 16, and 30 mbar, and they tend to split the differences between SBUV and LIMS. Additional comparisons with electrochemical concentration cell (ECC) sonde and Mastsonde ozone profiles are presented in an attempt to sort out the more noticeable differences. At tropical latitudes, LIMS ozone is too large in layer 4; no measurements were available for layer 3. SBUV is too high in layer 3. Layer 5 results are not conclusive, but LIMS appears high by about 10% while SBUV appears low by a similar percentage. At higher latitudes (38°–55°N) of the northern hemisphere, ECC and Mastsonde comparison results are not accurate enough to differentiate between SBUV and LIMS in layer 5, even though there are persistent differences in the satellite data of the order of 10–15%. LIMS ozone is about 10% larger than balloon values in layer 4 during northern hemisphere spring. Both SBUV and LIMS are too high in layer 3. The sign of the SBUV/LIMS satellite differences changes with latitude in layers 4 and 5, and the differences in layer 4 approach 20% at mid‐latitudes during late spring and summer. The May SBUV/LIMS differences at 30°N are similar to the SBUV/ECC differences found at Palestine, Texas (32°N) in the June 1983 Balloon Ozone Intercomparison Campaign (BOIC) I ozone intercomparison. All of this means that annual variations in the SBUV and LIMS satellite ozone data and their meridional gradients in the middle to lower stratosphere must be judged as only qualitative at this time.