Global validation of empirically corrected EP-Total Ozone Mapping Spectrometer (TOMS) total ozone columns using Brewer and Dobson ground-based measurements

This article focuses on the global‐scale validation of the empirically corrected Version
8 total ozone column data set acquired by the NASA Total Ozone Mapping Spectrometer
(TOMS) during the period 1996–2004 when this instrument was flying aboard the Earth
Probe (EP) satellite platform. This analysis is based on the use of spatially co‐located,
ground‐based measurements from Dobson and Brewer spectrophotometers. The original
EP‐TOMS V8 total ozone column data set was also validated with these ground‐based
measurements to quantify the improvements made by the empirical correction that was
necessary as a result of instrumental degradation issues occurring from the year 2000
onward that were uncorrectable by normal calibration techniques. EP‐TOMS V8‐corrected
total ozone data present a remarkable improvement concerning the significant negative
bias of around ∼3% detected in the original EP‐TOMS V8 observations after the year
2000. Neither the original nor the corrected EP‐TOMS satellite total ozone data sets show
a significant dependence on latitude. In addition, both EP‐TOMS satellite data sets
overestimate the Brewer measurements for small solar zenith angles (SZA) and
underestimate for large SZA, explaining a significant seasonality (∼1.5%) for cloud‐free
and cloudy conditions. Conversely, relative differences between EP‐TOMS and Dobson
present almost no dependence on SZA for cloud‐free conditions and a strong dependence
for cloudy conditions (from +2% for small SZA to −1% for high SZA). The dependence of
the satellite ground‐based relative differences on total ozone shows good agreement for
column values above 250 Dobson units. Our main conclusion is that the upgrade to TOMS
V8‐corrected total ozone data presents a remarkable improvement. Nevertheless, despite
its quality, the EP‐TOMS data for the period 2000–2004 should not be used as a source for
trend analysis since EP‐TOMS ozone trends are empirically corrected using NOAA‐16
and NOAA‐17 solar backscatter ultraviolet/2 data as external references, and therefore,
they are no longer considered as independent observations.
Citation: Antón, M., M. E. Koukouli, M. Kroon, R. D. McPeters, G. J. Labow, D. Balis, and A. Serrano (2010), Global
validation of empirically corrected EP‐Total Ozone Mapping Spectrometer (TOMS) total ozone columns using Brewer and
Dobson ground‐based measurements, J. Geophys. Res., 115, D19305, doi:10.1029/2010JD014178.