Differences in the Vertical Ozone Distribution Deduced from Umkehr and Ozonesonde Data at Goose Bay

Abstract

This study is devoted to a comparison between the vertical ozone distribution profiles obtained using indirect Umkehr and direct ozonesonde methods. In the three year period 1963?1965, there were 17 days with simultaneous Umkehr and ozonesonde profiles at 53N, 60W, predominantly in the winter-spring season. The mean ozone profiles indicate that the greatest differences occur at or about the level of the ozone maximum. The ozonesonde profile shows two maxima with the predominant one at about 20 km and a secondary one between 13 and 14 km, whereas the Umkehr profile shows only one maximum near 22 km. The center of gravity of the Umkehr profile is close to 21 km, and is about 1 km above that of the mean ozonesonde profile. Generally, the vertical ozone distribution obtained by both methods shows an approximately similar percentage distribution of the ozone amount. Only within the 15?24 km layer in all cases do the sondes give 9 per cent (of the total amount) more ozone content than the Umkehr method. Above 24 km the ozone partial pressure given from Umkehr is higher than it is from sondes. In this region the Umkehr profile gives 6 per cent (of the total amount) more ozone than the sondes. The correlation between the simultaneous changes in the integrated ozone within a given layer, estimated by alternative sampling methods, is high (≥0.80) between 10 and 19 km. Little relationship is found between them in the troposphere and above 24 km. The study suggests that direct comparisons of profiles taken by Umkehr and ozonesonde methods cannot be useful for the study of short-period and small-scale features.