Vertical ozone profile by Umkehr measurements at Syowa Station

Abstract

Dobson Umkehr measurement for derivation of the vertical ozone profile has been conducted at Syowa station (69.0°S, 39.6°E) in Antarctica since 1977. Introduction of a highly automated measuring system in 1994 at Syowa has brought about many opportunities and high quality data acquisition for Umkehr measurements. Short Umkehr measurement (A, C and D pairs) has been routinely conducted at Syowa, where solar zenith angle is generally high, except for the polar summer when the solar zenith angle is too low. In this study, recently re-evaluated N-value records acquired at Syowa and the new algorithm UMK04 are used to deduce ozone profiles. The ozone hole in 2006 was developed to the largest size ever observed, and at Syowa the lowest total ozone of 114 DU since the beginning of observation was recorded. Umkehr measurements also show extremely low ozone amount in each layer above Syowa. This is the minimum record in Umkehr data at Syowa since the beginning of observation in 1977. The ozone profiles for recent years show decreasing tendency in spring in the upper (about 40 km) and lower stratosphere.