HR: 11:35h
AN: A51G-05    [PDF]
TI: The Impact of the 1991 Pinatubo Volcanic Eruption on Climate Using a Vertically Resolved Stratospheric Aerosol Data Set Derived from SAGE II Observations
AU: * Stenchikov, G L
EM: gera@envsci.rutgers.edu
AF: Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901 United States
AU: Robock, A
EM: robock@envsci.rutgers.edu
AF: Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901 United States
AU: Hamilton, K
EM: kph@soest.hawaii.edu
AF: International Pacific Research Center, University of Hawaii, 2525 Correa Road, Honolulu, HA 96822 United States
AU: Ramaswamy, V
EM: vr@gfdl.noaa.gov
AF: NOAA Geophysical Fluid Dynamics Laboratory, P.O. Box 308, Princeton, NJ 08542 United States
AU: Schwarzkopf, M D
EM: ds@gfdl.noaa.gov
AF: NOAA Geophysical Fluid Dynamics Laboratory, P.O. Box 308, Princeton, NJ 08542 United States
AU: da Silva, A
EM: dasilva@gsfc.nasa.gov
AF: Goddard Space Flight Center, Mailstop 910.3, Greenbelt, MD 20771 United States
AU: Thomason, L W
EM: L.W.Thomason@nasa.gov
AF: NASA Langley Research Center, Mailstop 475, Hampton, VA 23693 United States
AB: Satellite observations of stratospheric aerosol extinction with the SAGE I, SAGE II, and SAM II instruments provide the best global coverage for the past two decades. The SAGE III instrument will continue this outstanding monitoring program. In addition SAGE provides the vertical structure of aerosol characteristics, which is important for calculation of aerosol radiative forcing and radiative heating of the lower stratosphere. Therefore these observations are invaluable for simulating the climate effects of stratospheric aerosols and their contribution to contemporary climate change. Most of our understanding of the impacts of volcanic eruptions comes from studies of the 1991 Mt. Pinatubo eruption in the Philippines, the largest and best observed eruption of the 20th century. Using SAGE II and CLAES/ISAMS satellite observations we have developed a spectral-, space-, and time-dependent set of aerosol parameters for two years after the Mt. Pinatubo eruption. Here we use this aerosol data set to study the effect of this eruption on the Arctic Oscillation (AO), accounting for the quasi-biennial oscillation (QBO) in the tropical stratosphere for the first time. We use the SKYHI troposphere-stratosphere-mesosphere climate model, which effectively assimilates observed zonal mean winds in the tropical stratosphere. The dynamical response to the Pinatubo eruption, with an enhanced positive mode of the AO, was reproduced by the model in the first and second Northern Hemisphere winters following the eruption, as observed. The phase of the QBO modulates climate system sensitivity to an external forcing. The QBO in its westerly phase strengthens the AO response. Because of nonlinear interactions, aerosols and the QBO together produce a stronger response than a linear superposition of responses to each of these forcings. Improved quantification of the QBO effect helps to better understand mechanisms of the stratospheric contribution to natural and externally forced climate variability.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0370 Volcanic effects (8409)
DE: 3309 Climatology (1620)
DE: 3319 General circulation
DE: 8409 Atmospheric effects (0370)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting