During the first four years of the implementation of the WMO Global Ozone Research and Monitoring Project, efforts were, to a large extent, concentrated on improving the quality and quantity of ozone observations. This was mainly achieved by upgrading almost half of the Dobson spectrophotometers in the global network.

        By mid-1979 it was becoming increasingly obvious that an assessment of the performance characteristics of various ozone observing systems was necessary, and the WMO Executive Committee approved a meeting on this subject in 1980, the report of which is available as Ozone Report No. 9. It was evident at that meeting that there was a pressing need for a comprehensive review that would attempt to quantify all the errors associated with the taking of ozone observations with Dobson spectrophotometers. This fact was further reinforced at the WMO Meeting of Experts on Source of Errors in Detection of Ozone Trends (Toronto, 1982, Ozone Report No. 12). Until that time, no such study had ever been undertaken. WMO consequently arranged for Dr. Reid E. Basher of the New Zealand Meteorological Service to prepare the review. Dr. Basher was uniquely qualified for the task, because he had spent some years at Oxford University in the United Kingdom, and had had access to the original papers of G.M.B. Dobson, the inventor of the spectrophotometer.

        This detailed report entitled "Review of Dobson Spectrophotometer Total Ozone Measurement Accuracy" is the result of his labours. As you will note, it contains chapters on every known and potential source of errors affecting Dobson instruments from a physics point of view, and where possible, quantifies the errors likely in the total ozone measurements, which the author prefers to refer to as "measurements of column ozone amount". This report should be considered as representing his own scientific findings and judgement.

        I wish to take this opportunity to thank Dr. Basher on behalf of the WMO Global Ozone Research and Monitoring Project for what has undoubtedly been a difficult and painstaking task.


Rumen D. Bojkov
December, 1982

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