Ozone and temperature trends in the upper stratosphere at five stations of the Network for the Detection of Atmospheric Composition Change

Abstract

Upper stratospheric ozone anomalies from the satellite-borne Solar Backscatter Ultra-Violet (SBUV), Stratospheric Aerosol and Gas Experiment II (SAGE II), Halogen Occultation Experiment (HALOE), Global Ozone Monitoring by Occultation of Stars (GOMOS), and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instruments agree within 5% or better with ground-based data from lidars and microwave radiometers at five stations of the Network for the Detection of Atmospheric Composition Change (NDACC), from 45°S to 48°N. From 1979 until the late 1990s, all available data show a clear decline of ozone near 40 km, by 10%–15%. This decline has not continued in the last 10 years. At some sites, ozone at 40 km appears to have increased since 2000, consistent with the beginning decline of stratospheric chlorine. The phaseout of chlorofluorocarbons after the International Montreal Protocol in 1987 has been successful, and is now showing positive effects on ozone in the upper stratosphere. Temperature anomalies near 40 km altitude from European Centre for Medium Range Weather Forecast reanalyses (ERA-40), from National Centers for Environmental Prediction (NCEP) operational analyses, and from HALOE and lidar measurements show good consistency at the five stations, within about 3 K. Since about 1985, upper stratospheric temperatures have been fluctuating around a constant level at all five NDACC stations. This non-decline of upper stratospheric temperatures is a significant change from the more or less linear cooling of the upper stratosphere up until the mid-1990s, reported in previous trend assessments. It is also at odds with the almost linear 1 K per decade cooling simulated over the entire 1979–2010 period by chemistry–climate models (CCMs). The same CCM simulations, however, track the historical ozone anomalies quite well, including the change of ozone tendency in the late 1990s.

Acknowledgements

It is not an easy task to put together consistent data sets over many years or even decades. This requires efforts by many people, contributing foresight, skill, dedication, and sometimes just a lot of hard work. The authors greatly acknowledge the excellent work of many people in the satellite and ground-based measurement communities, as well as in the weather forecasting centres. The provision of GOMOS and SCIAMACHY data by ESA is acknowledged. SCIAMACHY data analysis at the University of Bremen is funded by DLR (50EE0727) and ESA (SCIAMACHY Quality Working Group). The Chemistry Climate Model Validation Activity (CCMVal) is supported by WCRPs (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) project. We thank the modelling groups of AMTRAC (GFDL, USA), CCSRNIES (NIES, Tsukuba, Japan), CMAM (MSC, University of Toronto and York University, Canada), GEOSCCM (NASA/GSFC, USA), LMDZrepro (IPSL, France), MAECHAM4CHEM (MPI Mainz, Hamburg, Germany), MRI (MRI, Tsukuba, Japan), SOCOL (PMOB/WRC and ETHZ, Switzerland), ULAQ (University of L'Aquila, Italy), UMETRAC (UK Met Office, UK, NIWA, NZ), UMSLIMCAT (University of Leeds, UK), and WACCM (NCAR, USA) for providing their simulation runs, and we thank the British Atmospheric Data Centre for assistance with the CCMVal Archive.