Southern Hemisphere midlatitude ground-based measurements of ClONO2

Abstract

We report the first long-term analysis of the total column of ClONO2 from groundbased infrared solar absorption measurements recorded at Lauder, New Zealand. Between September 1990 and August 1994 the ClONO2 total column averaged 1.22(±0.4)×1015cm-2, in good agreement with previous airborne and spaceborne measurements at southern hemisphere midlatitudes. The monthly mean ClONO2 column over Lauder shows a clear seasonal cycle with a peak amplitude of 22(±3)% of the yearly mean with the seasonal maximum occurring in early September. This is the first measured seasonal variation of ClONO2. -from Authors Show more