Vertical profiles of the rate of linear change (trend) in the altitude range
15–50 km are determined from decadal O<sub>3</sub> time series obtained from
SCIAMACHY<sup>1</sup>/ENVISAT<sup>2</sup>
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 O<sub>3</sub>
trends of around 5% per decade are found in the upper stratosphere in
the tropics and at midlatitudes. Comparisons between SCIAMACHY and EOS
MLS<sup>3</sup> show
reasonable agreement both in the tropics and at midlatitudes for most
altitudes. In the tropics, measurements from OSIRIS<sup>4</sup>/Odin and SHADOZ<sup>5</sup> are also analysed. These yield rates of
linear change of O<sub>3</sub> 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.
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<br><br>
<sup>1</sup> SCanning Imaging Absorption spectroMeter for Atmospheric
CHartographY
<sup>2</sup> European environmental research satellite
<sup>3</sup> Earth Observing System (EOS) Microwave Limb Sounder (MLS)
<sup>4</sup> Optical Spectrograph and InfraRed Imager System
<sup>5</sup> Southern Hemisphere ADditional OZonesonde