1CESAM, Department of Physics, University of Aveiro, Portugal
2National Center for Atmospheric Research, Boulder, Colorado, USA
3Center for Limb Atmospheric Sounding, University of Colorado at Boulder, Boulder, Colorado, USA
4Goddard Earth Sciences Technology and Research, Morgan State University, Baltimore, Maryland, USA
Abstract. The statistical relationships among the variability of the area covered by double tropopause (DT) events, the strength of the tropical upwelling, the variabilities of total column ozone and of lower stratospheric water vapour are analyzed. The QBO and ENSO signals in the double tropopause and tropical upwelling as well as their influence on the statistical relationships are also presented. The analysis is based on both reanalysed data (ERA-Interim) and satellite data.
Significant anticorrelations were found between the area covered by double tropopause events and the total column ozone in the midlatitudes of the Northern Hemisphere. This relationship is confirmed by a large positive correlation between the areas covered by ozone laminae and double tropopause events as found in the HIRDLS satellite data. Significant anticorrelations were also found between the global area of double tropopause events and the near global (50° S–50° N) water vapour in the lower stratosphere.
The correlations of DT variables with total column ozone and ozone laminae are both consistent with the poleward displacement of tropical air with lower ozone mixing ratio and with tropospheric intrusions of tropical tropospheric air into the lower extratropical stratosphere.
Finally, a significant anticorrelation was found between the tropical upwelling and the near global lower stratospheric water vapour. The step like decrease in the lower stratospheric water vapour after 2001 is mirrored by a step like increase in the tropical upwelling.