Volcanic sulfate deposition to Greenland and Antarctica: A modeling sensitivity study

Toohey, Matthew, Krüger, Kirstin and Timmreck, Claudia (2013) Volcanic sulfate deposition to Greenland and Antarctica: A modeling sensitivity study Journal of Geophysical Research: Atmospheres, 118 (10). pp. 4788-4800. DOI 10.1002/jgrd.50428.

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Abstract

Reconstructions of the atmospheric sulfate aerosol burdens resulting from past volcanic eruptions are based on ice core-derived estimates of volcanic sulfate deposition and the assumption that the two quantities are directly proportional. We test this assumption within simulations of tropical volcanic stratospheric sulfur injections with the MAECHAM5-HAM aerosol-climate model. An ensemble of 70 simulations is analyzed, with SO2 injections ranging from 8.5 to 700 Tg, with eruptions in January and July. Modeled sulfate deposition flux to Antarctica shows excellent spatial correlation with ice core-derived estimates for Pinatubo and Tambora, although the comparison suggests the modeled flux to the ice sheets is 4–5 times too large. We find that Greenland and Antarctic deposition efficiencies (the ratio of sulfate flux to each ice sheet to the maximum hemispheric stratospheric sulfate aerosol burden) vary as a function of the magnitude and season of stratospheric sulfur injection. Changes in simulated sulfate deposition for large SO2 injections are connected to increases in aerosol particle size, which impact aerosol sedimentation velocity and radiative properties, the latter leading to strong dynamical changes including strengthening of the winter polar vortices, which inhibits the transport of stratospheric aerosols to high latitudes. The resulting relationship between Antarctic and Greenland volcanic sulfate deposition is nonlinear for very large eruptions, with significantly less sulfate deposition to Antarctica than to Greenland. These model results suggest that variability of deposition efficiency may be an important consideration in the interpretation of ice core sulfate signals for eruptions of Tambora-magnitude and larger.

Document Type: Article
Additional Information: WOS:000325272000062
Keywords: volcanic eruptions; ice cores; sulfate aerosol; sulfate deposition; aerosol transport
Research affiliation: OceanRep > SFB 574
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
DOI etc.: 10.1002/jgrd.50428
ISSN: 2169-8996
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 574256
Date Deposited: 16 Jul 2013 09:46
Last Modified: 06 Feb 2018 13:14
URI: http://eprints.uni-kiel.de/id/eprint/21561

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