Algorithm for the charge-coupled-device scanning actinic flux spectroradiometer ozone retrieval in support of the Aura satellite validation

Stratospheric ozone column data was acquired during four recent aircraft-based validation missions for the Aura satellite flown in years 2004-2006. The data was retrieved by the spectrally-resolved actinic flux measurements of the charge-coupled-device scanning actinic flux spectroradiometer (CAFS) instrument carried on board the NASA WB-57 and DC-8 aircrafts. Each dataset contains information on temporal and spatial variability in the stratospheric ozone column. Analyses of the CAFS datasets provide guidance for assimilation of data from individual satellite orbits into the global maps of stratospheric ozone. Moreover, the 10-second samplings of the CAFS data supply information on spatial variability of stratospheric ozone column across the footprint of a satellite measurement. The CAFS data is available as a function of altitude and geo location of the aircraft. This paper describes the algorithm for the retrieval of an ozone column above the aircraft level, along with validation of the CAFS retrieved ozone product. A discussion of the retrieval uncertainty is provided with emphasis on the algorithm's assumptions and instrumental uncertainties. Sensitivity of the ozone retrieval to fundamental atmospheric parameters is discussed in detail, and the range of uncertainties is estimated under a variety of observational conditions. The characteristic model uncertainty of the CAFS partial ozone column retrieval is better than 3 %, whereas the CAFS measurement precision contributes less than 1 % to the retrieval uncertainty.