Tropical tropospheric ozone and biomass burning

New methods for retrieving tropospheric ozone column depth and absorbing ae rosol (smoke and dust) from the Earth Probe-Total Ozone Mapping Spectromete r (EP/TOMS) are used to follow pollution and to determine interannual varia bility and trends. During intense fires over Indonesia (August to November 1997), ozone plumes, decoupled from the smoke below, extended as far as Ind ia, This ozone overlay a regional ozone increase triggered by atmospheric r esponses to the El Nino and Indian Ocean Dipole. Tropospheric ozone and smo ke aerosol measurements from the Nimbus 7 TOMS instrument show El Nino sign als but no tropospheric ozone trend in the 1980s. Offsets between smoke and ozone seasonal maxima point to multiple factors determining tropical tropo spheric ozone variability.