Climate Dynamics

, Volume 34, Issue 2, pp 381–398

Stratospheric temperature trends: impact of ozone variability and the QBO

  • Mauro Dall’Amico
  • Lesley J. Gray
  • Karen H. Rosenlof
  • Adam A. Scaife
  • Keith P. Shine
  • Peter A. Stott
Article

DOI: 10.1007/s00382-009-0604-x

Cite this article as:
Dall’Amico, M., Gray, L.J., Rosenlof, K.H. et al. Clim Dyn (2010) 34: 381. doi:10.1007/s00382-009-0604-x

Abstract

In most climate simulations used by the Intergovernmental Panel on Climate Change 2007 fourth assessment report, stratospheric processes are only poorly represented. For example, climatological or simple specifications of time-varying ozone concentrations are imposed and the quasi-biennial oscillation (QBO) of equatorial stratospheric zonal wind is absent. Here we investigate the impact of an improved stratospheric representation using two sets of perturbed simulations with the Hadley Centre coupled ocean atmosphere model HadGEM1 with natural and anthropogenic forcings for the 1979–2003 period. In the first set of simulations, the usual zonal mean ozone climatology with superimposed trends is replaced with a time series of observed zonal mean ozone distributions that includes interannual variability associated with the solar cycle, QBO and volcanic eruptions. In addition to this, the second set of perturbed simulations includes a scheme in which the stratospheric zonal wind in the tropics is relaxed to appropriate zonal mean values obtained from the ERA-40 re-analysis, thus forcing a QBO. Both of these changes are applied strictly to the stratosphere only. The improved ozone field results in an improved simulation of the stepwise temperature transitions observed in the lower stratosphere in the aftermath of the two major recent volcanic eruptions. The contribution of the solar cycle signal in the ozone field to this improved representation of the stepwise cooling is discussed. The improved ozone field and also the QBO result in an improved simulation of observed trends, both globally and at tropical latitudes. The Eulerian upwelling in the lower stratosphere in the equatorial region is enhanced by the improved ozone field and is affected by the QBO relaxation, yet neither induces a significant change in the upwelling trend.

Keywords

All-forcings simulations of recent climate assessed by the IPCC 2007 AR4Observed zonal mean ozone distributionsQBO of stratospheric equatorial zonal wind11-year solar cycleVolcanic eruptions of El Chichón and Mt. PinatuboVariability and trends of stratospheric temperatures

Copyright information

© Crown Copyright  2009

Authors and Affiliations

  • Mauro Dall’Amico
    • 1
    • 2
  • Lesley J. Gray
    • 1
  • Karen H. Rosenlof
    • 3
  • Adam A. Scaife
    • 4
  • Keith P. Shine
    • 5
  • Peter A. Stott
    • 6
  1. 1.NCAS Climate, Department of MeteorologyUniversity of ReadingReadingUK
  2. 2.Deutsches Zentrum für Luft-und RaumfahrtInstitut für Physik der AtmosphäreOberpfaffenhofenGermany
  3. 3.NOAA Earth System Research LaboratoryBoulderUSA
  4. 4.Met Office Hadley CentreExeterUK
  5. 5.Department of MeteorologyUniversity of ReadingReadingUK
  6. 6.Met Office Hadley CentreExeterUK