Stratospheric NO2 variations from a long time series at Lauder, New Zealand

Abstract

Eighteen years of NO2 measurements using zenith-scattered sunlight are analyzed for seasonal, cyclic, and episodic variability and secular trends. The analysis shows a marked increase in stratospheric NO2 over the period, corresponding to a trend of 5% per decade, and the influences of both the El Chichón and Pinatubo eruptions are clearly evident. Smaller effects of the El Niño-Southern Oscillation and quasi-biennial oscillation are apparent, but correlation with the solar cycle is poor after correction for autocorrelation. All of these effects are similar for sunrise and sunset NO2. Copyright 2000 by the American Geophysical Union.