Solar Backscatter UV (SBUV) total ozone and profile algorithm

[摘要] We describe the algorithm that has been applied to develop a 42 yr record oftotal ozone and ozone profiles from eight Solar Backscatter UV (SBUV)instruments launched on NASA and NOAA satellites since April 1970. TheVersion 8 (V8) algorithm was released more than a decade ago and has been inuse since then at NOAA to produce their operational ozone products. Thecurrent algorithm (V8.6) is basically the same as V8, except for updates toinstrument calibration, incorporation of new ozone absorption cross-sections,and new ozone and cloud height climatologies. Since the V8 algorithm has beenoptimized for deriving monthly zonal mean (MZM) anomalies for ozoneassessment and model comparisons, our emphasis in this paper is primarily oncharacterizing the sources of errors that are relevant for such studies. Whendata are analyzed this way the effect of some errors, such as verticalsmoothing of short-term variability, and noise due to clouds and aerosolsdiminish in importance, while the importance of others, such as errors due tovertical smoothing of the quasi-biennial oscillation (QBO) and other periodic and aperiodic variations, becomemore important. With V8.6 zonal mean data we now provide smoothing kernelsthat can be used to compare anomalies in SBUV profile and partial ozonecolumns with models. In this paper we show how to use these kernels tocompare SBUV data with Microwave Limb Sounder (MLS) ozone profiles. These kernels are particularlyuseful for comparisons in the lower stratosphere where SBUV profiles havepoor vertical resolution but partial column ozone values have high accuracy.We also provide our best estimate of the smoothing errors associated withSBUV MZM profiles. Since smoothing errors are the largest source ofuncertainty in these profiles, they can be treated as error bars in derivinginterannual variability and trends using SBUV data and for comparing withother measurements. In the V8 and V8.6 algorithms we derive total columnozone by integrating the SBUV profiles, rather than from a separate set ofwavelengths, as was done in previous algorithm versions. This allows us toextend the total ozone retrieval to 88° solar zenith angle (SZA).Since the quality of total column data is affected by reduced sensitivity toozone in the lower atmosphere by cloud and Rayleigh attenuation, which getsworse with increasing SZA, we provide our best estimate of these errors, aswell as the kernels that can be used to test the sensitivity of the derivedcolumns to long-term changes in ozone in the lower atmosphere.

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