Synchronous deposition of volcanic ash and sulfate aerosols over Greenland in 1783 from the Laki eruption (Iceland)

Sulfate aerosols from the 1783 - 1784 A. D. Laki eruption are widely used as a reference horizon for constraining Greenland ice core time scales, yet the timing of the arrival of the sulfate remains under discussion. Two ice cores from western Greenland, analyzed with high temporal resolution, confirm that sulfate aerosols arrived over Greenland late in 1783, concomitant with the tephra, elevated concentrations of Cd, Bi, and Tl, all indicators of volcanic emissions, and with a short-lived Rare Earth Elements anomaly. Thereafter sulfate deposition declined rapidly. Very modest concentrations of sulfate in 1784 snowfall, evident in six Greenland cores, suggest a relatively short (less than 1 year) atmospheric residence time and an injection height limited to the lower stratosphere. An improved estimate of the associated stratospheric sulfate burden is calculated and provides an important input for models assessing climatic impacts of this volcanic eruption.