The Greenland Ice Sheet provides an excellent archive for the paleoclimatic and paleoenvironmental conditions, particularly for the Northern Hemisphere. The chemical analyses of five multi-century Greenland ice cores have yielded a high resolution volcanic aerosol history. This provides an improved estimate of the stratospheric sulfate burden, which is an important input for models assessing the climatic impacts of volcanic eruptions. Additionally, these cores made it possible to confirm the timing of the arrival of the ash and aerosols from Laki over Greenland, which is essential for dating ice cores from low accumulation region in Greenland.
The spatial characteristics of the sulfate aerosol deposition associated with specific eruptions provide information about the transport processes and the mechanisms dominating local deposition. Examination of the sulfate deposited from the 1783-84 A.D. Laki and the 1815 A.D. Tambora eruptions reveals that precipitation over the southeastern regions in 1783 may have been suppressed. This also suggests that Laki aerosols were likely deposited primarily by dry deposition. In contrast, the Tambora sulfate is more spatially homogeneous, suggesting deposition primarily via wet processes. To quantify the impact of geographical factors on the deposition of volcanic sulfate over Greenland, a category explanatory variable analysis was conducted. The results indicate that the location of ice cores relative to the ice divide strongly affects EXS deposition, but the elevation of the core site is relatively unimportant.
Since 1850, the EXS flux extracted from Greenland ice cores has increased primarily due to anthropogenic sulfur emissions. To quantify this impact as well as the accumulation effect, a linear mixed model was applied. The results indicate that for every Gg increase in the annual NH sulfur emissions, there is a 0.0013% increase in the annual non-volcanic sulfate flux. The impact of accumulation on sulfate deposition varies over Greenland, likely as a function of the dominant local depositional mechanisms. Additionally, as local sources as well as the depositional and post-depositional processes may affect the sulfate deposition on the ice sheet, it will be valuable to reconstruct the histories of other contributor and to closely examine the depositional processes.