Atmos. Chem. Phys. Discuss., 13, 4601-4635, 2013
© Author(s) 2013. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Uncertainties in modelling the stratospheric warming following Mt. Pinatubo eruption
F. Arfeuille1,2, B. P. Luo1, P. Heckendorn1, D. Weisenstein3, J. X. Sheng1, E. Rozanov1,4, M. Schraner5, S. Brönnimann2, L. W. Thomason6, and T. Peter1
1Institute for Atmospheric and Climate Science ETH Zurich, Zurich, Switzerland
2Oeschger Center for Climate Change Research and Institute of Geography, University of Bern, Bern, Switzerland
3School of Engineering and Applied Science, Harvard University, Cambridge, MA, USA
4Physical-Meteorological Observatory/World Radiation Center, Davos, Switzerland
5Federal office of Meteorology and Climatology, Meteoswiss, Zürich, Switzerland
6NASA Langley Research Center, Hampton, Virginia, USA

Abstract. In terms of atmospheric impact, the volcanic eruption of Mt. Pinatubo (1991) is the best characterized large eruption on record. We investigate here the stratospheric warming following the Pinatubo eruption derived from SAGE II extinction data including most recent improvements in the processing algorithm and a data filling procedure in the opacity-induced "gap" regions. From these data, which cover wavelengths of 1.024 micrometer and shorter, we derived aerosol size distributions which properly reproduce extinction coefficients at much longer wavelength. This provides a good basis for calculating the absorption of terrestrial infrared radiation and the resulting stratospheric heating. However, we also show that the use of this dataset in the global chemistry-climate model (CCM) SOCOL leads to exaggerated aerosol-induced stratospheric heating compared to observations, even partly larger than the already too high values found by many models in recent general circulation model (GCM) and CCM intercomparisons. This suggests that the overestimation of the stratospheric warming after the Pinatubo eruption arises from deficiencies in the model radiation codes rather than an insufficient observational data basis. Conversely, our approach reduces the infrared absorption in the tropical tropopause region, in better agreement with the post-volcanic temperature record at these altitudes.

Citation: Arfeuille, F., Luo, B. P., Heckendorn, P., Weisenstein, D., Sheng, J. X., Rozanov, E., Schraner, M., Brönnimann, S., Thomason, L. W., and Peter, T.: Uncertainties in modelling the stratospheric warming following Mt. Pinatubo eruption, Atmos. Chem. Phys. Discuss., 13, 4601-4635, doi:10.5194/acpd-13-4601-2013, 2013.
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