1Institute for Atmospheric and Climate Science ETH Zurich, Zurich, Switzerland
2Oeschger Centre 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, VA, USA
Received: 10 Dec 2012 – Published in Atmos. Chem. Phys. Discuss.: 18 Feb 2013
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 model-derived stratospheric warming following the Pinatubo eruption as derived from SAGE II extinction data including recent improvements in the processing algorithm. This method, termed SAGE_4λ, makes use of the four wavelengths (385, 452, 525 and 1024 nm) of the SAGE II data when available, and uses a data-filling procedure in the opacity-induced "gap" regions. Using SAGE_4λ, we derived aerosol size distributions that properly reproduce extinction coefficients also at much longer wavelengths. 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 data set in a global chemistry–climate model (CCM) still leads to stronger aerosol-induced stratospheric heating than observed, with temperatures partly even higher 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warming after the Pinatubo eruption may not be ascribed to an insufficient observational database but instead to using outdated data sets, to deficiencies in the implementation of the forcing data, or to radiative or dynamical model artifacts. Conversely, the SAGE_4λ approach reduces the infrared absorption in the tropical tropopause region, resulting in a significantly better agreement with the post-volcanic temperature record at these altitudes.
Revised: 03 Sep 2013 – Accepted: 07 Oct 2013 – Published: 18 Nov 2013
Arfeuille, F., Luo, B. P., Heckendorn, P., Weisenstein, D., Sheng, J. X., Rozanov, E., Schraner, M., Brönnimann, S., Thomason, L. W., and Peter, T.: Modeling the stratospheric warming following the Mt. Pinatubo eruption: uncertainties in aerosol extinctions, Atmos. Chem. Phys., 13, 11221-11234, doi:10.5194/acp-13-11221-2013, 2013.