GLOBAL CF2CL2 MEASUREMENTS BY UARS CRYOGENIC LIMB ARRAY ETALON SPECTROMETER - VALIDATION BY CORRELATIVE DATA AND A MODEL

The cryogenic limb array etalon spectrometer (CLAES) onboard the Upper Atmosphere Research Satellite (UARS) has obtained the first global me asurements of CF2Cl2 over six seasons, for which 388 days have been pr ocessed in data version 7 for the period from January 9, 1992, to May 5, 1993. The CLAES measurements provide a near-global view of this str atospheric species, greatly extending the altitude, latitude, and seas onal coverage of previous measurements. This work evaluates CLAES vers ion 7 data set quality. To arrive at estimates of experimental error, we compared the CLAES CF2Cl2 profiles with all of the available correl ative data from balloon and space-borne sensors, and we looked at the repeatability of multiple profiles in the same location. In addition, we carried out empirical estimates of experimental error based on know ledge of instrument characteristics, and we performed consistency chec ks using the Lawrence Livermore National Laboratory two-dimensional (L LNL-2D) model and the CLAES N2O data set. Both the range of mean diffe rences between CLAES and the available correlative data and the empiri cal estimates of the instrument systematic error indicate a CF2Cl2 pro file systematic error of 14% over the range of 18.7 through 32 km and 22% for 33-35 km and 16-18 km. These systematic errors are applicable in the spring through fall seasons for the midlatitude region and all seasons in the tropical region. The CF2Cl2 estimated random errors, wh ich are close to the observed data repeatability, are 32 to 11 pptv be tween 17 and 32 km and translate to an average 9% in the low to midstr atosphere. The altitude range of best confidence for the CF2Cl2 mixing ratio profiles is 18.7 to 32 km (similar to 68 to 10 mbar), to which we assign an accuracy (root-sum-square of systematic and random errors ) of similar to 17%. In the tropics the profiles from 16 to about 26 k m may sometimes be biased low by up to 14% due to a data processing al gorithm constraint. The CLAES CF2Cl2 global fields show generally good spatial correlation and exhibit the major morphological and seasonal features seen in other global tracer field data. Overall, the results of this validation exercise indicate that the CLAES version 7 CF2Cl2 d ata set, within the limitations discussed in the paper, can be used fo r quantitative and qualitative studies of stratospheric structure and dynamics.