HR: 13:45h
AN: A53B-02    [Abstracts]
TI: Trends in Non-Volcanic Stratospheric Aerosol Determined from 30 Years of Aerosol Measurements by Lidar and Balloon-borne Particle Counters
AU: * Deshler, T
EM: deshler@uwyo.edu
AF: University of Wyoming, Department of Atmospheric Science, 1000 E. Univ. Ave., Laramie, WY 82071 United States
AU: Anderson-Sprecher, R
EM: Sprecher@uwyo.edu
AF: University of Wyoming, Dept. of Statistics, 1000 E. Univ. Ave., Laramie, WY 82071 United States
AU: J„ger, H
EM: horst.jaeger@imk.fzk.de
AF: Institut fr Meteorologie und Klimaforschung, Atmosph„rische Umweltforschung, Forschungzentrum, Karsruhe, Germany
AU: Barnes, J
EM: John.E.Barnes@noaa.gov
AF: National Oceanic and Atmospheric Administration, R/CMDL, Boulder, CO 80305 United States
AU: Hofmann, D
EM: David.J.Hofmann@noaa.gov
AF: National Oceanic and Atmospheric Administration, R/CMDL, Boulder, CO 80305 United States
AU: Clemesha, B
EM: bclem@laser.inpe.br
AF: Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758 , S. J. dos Campos, Brazil
AU: Simonich, D
EM: simonich@laser.inpe.br
AF: Instituto Nacional de Pesquisas Espaciais, Avenida dos Astronautas, 1758 , S. J. dos Campos, Brazil
AB: Junge's initial stratospheric aerosol measurements (1959-1960), at the end of a long volcanically quiescent period, and the long term stratospheric aerosol measurements beginning in the 1970s have been investigated for trends in non-volcanic stratospheric aerosol. These investigations have focused on the inter-volcanic "background" periods, which until post Pinatubo, have been rather brief. Since 1959 there have been approximately 30 eruptions with volcanic explosivity indices of 4 or more. The five 30 year records of stratospheric aerosol are comprised of one in situ record [aerosol concentration for 0.15 and 0.25 um radius particles above Laramie, Wyoming, USA (1971-2003, 41N)] and four lidar records [S. J. dos Campos, Brazil (1972-2003, 23S), Mauna Loa, Hawaii, USA (1974-2003, 20N), Hampton, Virginia, USA (1974-2002, 37N), Garmisch-Partenkirchen, Germany (1976-2002, 48N)]. These data capture the three major aerosol-producing eruptions, Fuego, El Chich˘n and Pinatubo, as well as the three inter-volcanic background periods. These records form the basis for an assessment of the trend in background stratospheric aerosol. The quantities to be investigated are integral number concentrations and integrated backscatter above the tropopause. These records were analyzed following two approaches. First the 3 volcanically quiescent periods are compared using a standard analysis of variance approach. Second an empirical model is used to remove the volcanic signal from the long term records and then the residuals are investigated for trends. The model is a parametric exponential decay model, requiring 4 parameters for each volcano and 2 parameters for background. The optimization procedure uses a priori estimates for each parameter and then standard squared-error residual minimization to obtain the set of parameters providing the minimum in the residuals. The baseline and autocorrelated residuals are then investigated for trend. The results suggest that the trend in background stratospheric aerosol is not significantly different than zero for S. J. dos Campos, Mauna Loa, and Garmisch, with a slight negative trend for the Hampton and Laramie data. This approach does not permit investigations of microphysical changes such as changing size distribtutions. This work forms part of the SPARC assessment of stratospheric aerosol.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0340 Middle atmosphere--composition and chemistry
DE: 8409 Atmospheric effects (0370)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly