Stratospheric ozone trends and variability as seen by SCIAMACHY from 2002 to 2012

Abstract

Vertical profiles of the rate of linear change (trend) in the altitude range 15–50 km are determined from decadal O₃ time series obtained from SCIAMACHY¹/ENVISAT² measurements in limb-viewing geometry. The trends are calculated by using a multivariate linear regression. Seasonal variations, the quasi-biennial oscillation, signatures of the solar cycle and the El Niño–Southern Oscillation are accounted for in the regression. The time range of trend calculation is August 2002–April 2012. A focus for analysis are the zonal bands of 20° N–20° S (tropics), 60–50° N, and 50–60° S (midlatitudes). In the tropics, positive trends of up to 5% per decade between 20 and 30 km and negative trends of up to 10% per decade between 30 and 38 km are identified. Positive O₃ trends of around 5% per decade are found in the upper stratosphere in the tropics and at midlatitudes. Comparisons between SCIAMACHY and EOS MLS³ show reasonable agreement both in the tropics and at midlatitudes for most altitudes. In the tropics, measurements from OSIRIS4/Odin and SHADOZ⁵ are also analysed. These yield rates of linear change of O₃ similar to those from SCIAMACHY. However, the trends from SCIAMACHY near 34 km in the tropics are larger than MLS and OSIRIS by a factor of around two. ¹ SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY ² European environmental research satellite ³ Earth Observing System (EOS) Microwave Limb Sounder (MLS) ⁴ Optical Spectrograph and InfraRed Imager System ⁵ Southern Hemisphere ADditional OZonesondes