A new self‐calibration method applied to TOMS and SBUV backscattered ultraviolet data to determine long‐term global ozone change

Abstract

The currently archived (1989) total ozone mapping spectrometer (TOMS) and solar backscattered ultraviolet (SBUV) total ozone data (version 5) show a global average decrease of about 9.0% from November 1978 to November 1988. This large decrease disagrees with an approximate 3.5% decrease estimated from the ground-based Dobson network. The primary source of disagreement was found to arise from an overestimate of reflectivity change and its incorrect wavelengths dependence for the diffuser plate used when measuring solar irradiance. Both of these factors have led to an overestimate of the rate of atmospheric ozone depletion by SBUV and TOMS. For total ozone measured by TOMS, a means has been found to use the measured radiance-irradiance ratio from several wavelengths pairs to construct an internally self consistent calibration. The method uses the wavelength dependence of the sensitivity to calibration errors and the requirement that albedo ratios for each wavelength pair yield the same total ozone amounts. Smaller errors in determining spacecraft attitude, synchronization problems with the photon counting electronics, and sea glint contamination of boundary reflectivity data have been corrected or minimized. New climatological low-ozone profiles have been incorporated into the TOMS algorithm that are appropriate for Antarctic ozone hole conditions and other low ozone cases. The combined corrections have led to a new determination of the global average total ozone trend (version 6) as a 2.9 -+ 1.3% decrease over 11 years (October 1978 to November 1989). Version 6 data are shown to be in agreement within error limits with the average of 39 ground-based Dobson stations and with the world standard Dobson spectrometer 83 at Mauna Loa, Hawaii. The global average ozone trend from version 6 data shows the presence of varying short-period trends (1979 to 1983, -0.33%/yr; 1983 to 1986, -0.91% yr, and 1986 to 1990, +0.16%/yr) that are partially masked in the original version 5 trends.

Investigating the Temporal and Spatial Variability of Total Ozone Column in the Yangtze River Delta Using Satellite Data: 1978–2013

“…Moreover, only Lin'an station is located in the Yangtze River Delta; however, it no longer provides new data. Fortunately, TOC measurements derived from remotely sensed data collected by multiple satellite platforms have been demonstrated to be effective to quantify the spatiotemporal variability of TOC at various scales by many researchers [22,[25][26][27][28][29][30][31]. At the same time, the studies on the TOC variations in YRD are scarce so far.…”

Search for evidence of trend slow-down in the long-term TOMS/SBUV total ozone data record: the importance of instrument drift uncertainty

“…The instrument drift uncertainty is difficult to assess. Herman et al (1991) did a thorough evaluation of drift uncertainty for the Nimbus 7 TOMS during its first decade of measurements. The authors estimated the drift uncertainty in each component of the calibration for the Nimbus 7 TOMS instrument and propagated these through the entire algorithm process.…”

Boreas RSS-10 Toms Circumpolar One-Degree Par Images

“…Errors associated with sea-glint contamination and spacecraft attitude were also corrected in Version 6. Details on the wavelength and radiometric calibration for Nimbus-7 TOMS is given by McPeters et al (1993McPeters et al ( , 1996, and Herman et al (1991).…”

“…The Nimbus-7 TOMS data archive was reprocessed in Version 6 to account for effects of diffuser plate degradation on the measured irradiance (Herman et al, 1991 None given.…”