Modeling the stratospheric warming following the Mt. Pinatubo eruption: uncertainties in aerosol extinctions 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 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
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observational database but instead to using outdated data sets, to deficiencies in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
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.: 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.