Validation of the TOR fields using this methodology is extremely difficult. An initial comparison of TOR values with a number of ozonesonde stations showing the improvement of the application of the empirical correction to the lowest three levels of the Version 6 SBUV archive was presented in Fishman et al. [2003] [PDF]. Another validation study showing how the TOR accurately captures the horizontal gradient of the monthly climatological values of tropospheric column ozone derived from long-term ozonesonde stations was presented in Creilson et al. [2003; see Figure 8].

The most comprehensive validation study was recently published in Wozniak et al. [2005]. Although the validation of TOR fields is extremely difficult without intensive dedicated field missions, the other product generated by the TOR methodology, namely the stratospheric column ozone (SCO), can be compared against available measurements derived from both in situ and satellite techniques. In turn, these satellite measurements have undergone intensive scrutiny since they have been used to assess how much ozone has been destroyed due to the release of chlorofluorocarbons [WMO, 1999; WMO, 2003]. A comparison between the SCO values derived from our empirically corrected SBUV methodology and the SCO derived from SAGE is shown in Figure 9.

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