Calibration of the NOAA 11 solar backscatter ultraviolet (SBUV/2) ozone data set from 1989 to 1993 using in‐flight calibration data and SSBUV

Abstract

Total ozone and ozone profiles are currently being measured by solar backscatter ultraviolet (SBUV/2) instruments onboard NOAA polar orbiting spacecraft using the backscattered ultraviolet technique. The NOAA 11 SBUV/2 operational data set was reprocessed from January 1989 to May 1993 and is now called version 6. The version 6 data include an updated algorithm and revised prelaunch and postlaunch calibrations of the geometrical albedo observations used to derive ozone values. Only the calibration revisions are described in this paper. The postlaunch revisions remove time dependent errors in the ozone amounts due to instrument drift, while the revised prelaunch calibration corrects the absolute value of retrieved ozone. The prelaunch corrections are a result of calibration checks from in‐orbit comparisons of ultraviolet geometric albedos measured by shuttle SBUV (SSBUV) and the NOAA 11 SBUV/2. Geometric albedo comparison data are further corrected using a radiative transfer code to account for the small difference in observing conditions between the two spacecraft. The postlaunch corrections rely on in‐flight calibration and solar irradiance data to account for time dependent changes in instrument gain, thermal response, and instrument diffuser degradation over time. Comparison of data from three SSBUV flights, which occurred about one year apart, with concurrent SBUV/2 data provided an independent check of the time dependent change derived from the in‐flight calibration data. Time independent corrections result in an increase of about 1% for total ozone, 5% for ozone at 1 mbar, and near 0% at 15 mbar. The time dependent corrections amount to an increase of 2% for total ozone, 10% for ozone near 1 mbar, and 3% at 15 mbar at the end of the current record in May 1993. Recent laboratory studies indicate that the absolute radiance calibrations may still be in error by a few percent which results in ozone profile values that are too low. The SBUV/2 total and ozone profile data are compared to the Nimbus SBUV data during the period when the data overlapped. Total ozone values agree to about 1%, while ozone profile differences range from −4% to +6%, depending on latitude and altitude, relative to SBUV. These differences are not statistically significant given the uncertainties of the two data sets.

Vertical Structure of the Anomalous 2002 Antarctic Ozone Hole

“…Some calibration parameters, such as changes in detector gain range ratio, are monitored and updated daily (Kondragunta et al 2000). Other calibration parameters, such as changes in solar diffuser plate reflectivity and changes in detector nonlinearity correction, use extrapolated characterizations and are updated less frequently (Hilsenrath et al 1995;Ahmad et al 1994). The latest calibration update for NOAA-16 SBUV/2 was implemented in June 2002.…”

Long‐term evolution of upper stratospheric ozone at selected stations of the Network for the Detection of Stratospheric Change (NDSC)

“…The NDSC data are compared to three long‐term satellite data sets: The 1979 to 2003 data set from various Solar Backscatter Ultraviolet instruments (SBUV) [ Hilsenrath et al , 1995; Bhartia et al , 1996], the 1979 to 2004 data set from the Stratospheric Aerosol and Gas Experiment I and II (SAGE) [ McCormick et al , 1989], and the 1991 to 2004 data set from the HALogen Occultation Experiment (HALOE) [ Russell et al , 1993].…”

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

“…The current MOD total ozone data set includes measurements from 6 satellites: Nimbus 7 TOMS, Nimbus 7 SBUV, NOAA 9, 11, and 16 SBUV/2s, and Earth Probe (EP) TOMS (Heath et al, 1975;Frederick et al, 1986;Hilsenrath et al, 1995;McPeters et al, 1996;McPeters et al, 1998). We use the data released by the individual instrument teams, and then apply additional adjustments to each record such that the merged data set is calibrated relative to a reference standard.…”