Tropospheric ozone derived from TOMS/SBUV measurements during TRACE A

The use of data from Total Ozone Mapping Spectrometer (TOMS) and Solar Backscatter Ultraviolet (SEW) measurements to develop daily maps of the amount of ozone in the troposphere during Transport and Atmospheric chemistry Near the Equator-Atlantic (TRACE A) is presented. By comparing these maps with available ozone measurements from sensors aboard the NASA DC-8, we show that the agreement between the satellite-derived measurements and the other data is generally very good. The TOMS/SBUV technique successfully captures large-scale gradients and the derived integrated tropospheric ozone amount is generally within 10-15% of the observed amounts. The largest discrepancy between the two data sets occurs when copious amounts of lower-tropospheric (1-6 km) aerosols (from intense widespread biomass burning) are present. The amount of ozone found over the TRACE A region for the September-October 1992 period agrees well with the climatological values published previously using TOMS and Stratospheric Aerosol and Gas Experiment (SAGE) measurements and with ozonesonde measurements from several tropical sites established as part of TRACE A. The satellite-derived ozone maximum observed during TRACE A is similar to 1000 km north of the previously published climatological data and it is not obvious whether or not this northward shift is due to normal interannual variability, or if it is a result of systematic data processing differences between the SAGE and the SBUV data sets.