Total ozone determinations from National Oceanic and Atmospheric Administration operational solar backscattered ultraviolet 2 instrument observations: An update

Total ozone amounts have been derived from observations of the Solar Backsc attered Ultraviolet 2 (SBUV/2) instruments on National Oceanic and Atmosphe ric Administration (NOAA) operational satellites since 1985. The data from the NOAA-9 instrument for the period 1985-1997 have been reprocessed using instrument characterizations based on in-orbit operation and comparisons wi th Shuttle Solar Backscattered Ultraviolet (SSBUV) observations. The data f rom the NOAA-11 satellite for the period 1989-1994 have also been reprocess ed using mainly internal spacecraft information. The data from the NOAA-14 satellite for the period 1995-1998 have been reprocessed using complete ins trument characterization. The NOAA-11 and NOAA-14 data for 1998 to the pres ent, briefly discussed herein, are preliminary. The calibration adjustments used in the reprocessing of NOAA-9, NOAA-11, and NOAA-14 total ozone data are internal, with the exception of those derived from SSBUV analysis, and are independent of Dobson and Total Ozone Mapping Spectrometer (TOMS) total ozone measurements. The reprocessed data have been validated with ground-b ased Dobson spectrophotometer observations, and are compared to other sourc es of total column ozone amounts. The mean bias between NOAA-9 data and Dob son data is 1.9% +/- 0.6% over the 12-year record with a trend of 0.1% per year. The mean bias between NOAA-11 and Dobson data is 0.8% +/- 0.2% with a near-zero trend. The mean bias between NOAA-14 and Dobson data is 1.5% +/- 0.3% with a trend of 0.2% per year; the NOAA-14 calibration and characteri zation data for the period 1998 to the present are not yet fully analyzed. The methods used in the validations are discussed here, as are some reasons for the results. Finally, a recommendation is made for the use of a relati vely continuous total ozone data set.