Tropical Tropospheric Ozone From Nimbus 7 and Earth-Probe Toms: Validation, ENSO Signals and Trends

The well-known wave-one pattern seen in tropical total ozone has been used to develop a modified-residual (MR) method for retrieving time-averaged stratospheric ozone and tropospheric ozone column amount from TOMS (Total Ozone Mapping Spectrometer) over the 14 complete years of Nimbus 7 observations (1979-1992) and from Earth-Probe (1996-present) and ADEOS/TOMS (1996-1997). Nine- to sixteen-day averaged tropical tropospheric ozone (TTO) maps show a seasonality expected from dynamical and chemical influences. Validation of the TTO time-series is presently limited to Atlantic sounding stations, notably Ascension Island, Natal, Brazil, and Brazzaville, Congo. Stratospheric column ozone, which is also derived from the modified-residual method, compares well with sondes and with stratospheric ozone column derived from other satellites.