On the total ozone depletion over Greece derived from satellite-flown and ground-based instruments

Abstract

There is abundant evidence of the depletion of atmospheric ozone concentration, both from ground-based measurements and from satellite data. However, one set of data published in 1989 by Bais et al. relating to Thessaloniki, in northern Greece, reported no depletion but rather said ‘the period March 1982 to March 1988 shows an insignificant change of total ozone, of about +0-02 per cent per year’. The data of Thessaloniki, obtained from the same instrument (Brewer spectrophotometer no. 5) as that used by Bais et al. has now also been published in the Red Book. In this paper we examine TOMS data for Thessaloniki, Athens and Crete for the six-year period from March 1982 to March 1988 and find a common ozone depletion of the order of 30 per cent during this period, for each of these three sites, including Thessaloniki; this is in contradiction to the results of Bais et al. for Thessaloniki. We have analysed the Red Book data for Thessaloniki and found that it shows total ozone depletion consistent with the results obtained from TOMS data, which are themselves consistent with results from other ground-based measurements in mid-latitudes. It is concluded that there are errors both in the data presented by Bais et al. and in their analysis and, in particular, that their statement quoted above is incorrect and should be disregarded.