A Comparison of AURA-OMI Column Ozone Values to Values from Recalibrated Earth-Probe TOMS

The front optics of the Total Ozone Mapping Spectrometer (TOMS) onboard the Earth Probe satellite have degraded over time causing a complex change in the instrument's sensitivity. Due to diminished accuracy resulting from this degradation, EP/TOMS total column ozone data from late 2001 to the present are not recommended for the calculation of long-term ozone trends. Attempts to correct the data based on physical principles have been unsuccessful. Therefore, an empirical calibration technique has been employed to adjust the TOMS ozone values during this time period. Total ozone comparisons in daily coincident matchups of the NOAA-16 Solar Backscatter UltraViolet (SBUV/2) and EP/TOMS showed a distinct time-dependent and solar zenith angle-dependent change in the EP/TOMS data. These differences were used to make simple ozone corrections to the ozone values in the TOMS data. The corrected dataset was compared to ground-based measurements and to data from the Ozone Monitoring Instrument (OMI) aboard NASA's Aura spacecraft. Results showed a much better agreement between EP/TOMS and OMI total ozone after the SBUV-based corrections were applied.