The stratospheric sulfur burden: an assessment based on gas and particle phase measurements

Monday, 19 March 2018
Iriarte (Hotel Botanico)
Terry Deshler1, Corinna Kloss2, Larry Willis Thomason3, Michael Hoepfner4, Bengt G Martinsson5, Stefanie Kremser6, Adam E Bourassa7, Norbert Glatthor8, John Edward Barnes9, Marc von Hobe10, Markus Hermann11, Nicholas B Jones12, Thomas Trickl8, Justus Notholt13, James C Wilson14, Mathias Palm13, Dan Smale15, James W Hannigan16, Ben Liley17, Osamu Uchino18, Sergey M. Khaykin19 and Annika Günther8, (1)LASP University of Colorado, Laramie, WY, United States, (2)Forschungszentrum, Jülich, Germany, (3)NASA Langley Research Center, Hampton, VA, United States, (4)Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Karlsruhe, Germany, (5)Lund University, Lund, Sweden, (6)Bodeker Scientific, Alexandra, New Zealand, (7)University of Saskatchewan, Saskatoon, SK, Canada, (8)Karlsruhe Institute of Technology, Karlsruhe, Germany, (9)NOAA, Hilo, HI, United States, (10)Forschungszentrum Jülich GmbH, Inst. of Energy and Climate Research (IEK-7), Juelich, Germany, (11)Leibniz Institute for Tropospheric Research, Leipzig, Germany, (12)Univ Wollongong, Wollongong, Australia, (13)University of Bremen, Bremen, Germany, (14)Univ Denver, Denver, CO, United States, (15)National Institute of Water and Atmospheric Research, Wellington, New Zealand, (16)National Center for Atmospheric Research, Boulder, CO, United States, (17)National Institute of Water and Atmospheric Research, Lauder, New Zealand, (18)NIES, Tsukuba, Japan, (19)LATMOS Laboratoire Atmosphères, Milieux, Observations Spatiales, LATMOS, Paris Cedex 05, France
Abstract:
Sulfur, by far the most common element found in stratospheric aerosol, appears in the particles due to the low vapor pressure of sulfuric acid which leads to quick condensation on pre-existing particles or homogeneous nucleation in regions of high sulfuric acid concentrations. The sulfuric acid arises through several oxidations of sulfur dioxide (SO2), ultimately by OH. Due to abundance of water, compared to sulfuric acid, the particles quickly take on water and grow. The SO2 appears in the stratosphere either through direct injection, or the photolysis and subsequent oxidation of carbonyl sulfide (OCS). Both SO2 and OCS are transported into the stratosphere through the upwelling caused by tropical convection, the Brewer Dobson circulation, and sporadic volcanic eruptions. Volcanic eruptions are particularly important for SO2. Due to the abundance of sulfur in stratospheric aerosol and to the reliance of that aerosol on gas phase sources of sulfur, an estimate of the sulfur burden from both phases is important to assess stratospheric aerosol and requires profile measurements of stratospheric aerosol, SO2 and OCS. Regular profile measurements of particle phase sulfur began in the 1970s at selected locations using lidar and balloon-borne instruments. The particle measurements became global in the 1980s with satellite-borne instruments. Regular measurements of gas phase sulfur began with ground based measurements at selected locations in the 1980s and became global in the 2000s with satellite-based instruments. Here details of estimations of the sulfur component from the particle measurements of either aerosol extinction, backscatter, limb scatter, or size distribution are presented along with results from gas phase measurements of SO2 and OCS. The temporal and spatial coverage of the measurements will be described, as well as inherent measurement uncertainties arising from instrumental factors, and the assumptions required. Integrals of the sulfur mixing ratios derived will provide a map of the stratospheric sulfur burden available from measurements. Interpolation and extrapolation of the sulfur burden can be used to provide a rudimentary temporal history of the global stratospheric sulfur burden since the beginning of this century, and perhaps earlier.
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