Atmospheric methane sulfonate and non‐sea‐salt sulfate records at the European Project for Ice Coring in Antarctica (EPICA) deep‐drilling site in Dronning Maud Land, Antarctica

Abstract

During three summer campaigns in January/February 2000, 2001, and 2002 the ionic composition of the aerosol at the European Project for Ice Coring in Antarctica (EPICA) deep‐drilling site at Kohnen Station was measured in daily resolution. In 2000 and 2002 we observed mean (±std) non‐sea‐salt sulfate (nss‐SO42−) concentrations of 353 ± 100 ng m−3 and 320 ± 250 ng m−3, as well as methane sulfonate (MS) concentrations of 59 ± 36 ng m−3 and 74 ± 80 ng m−3, respectively. For the summer campaign in 2001, significantly lower nss‐SO42− and MS levels of 164 ± 150 ng m−3 and 19 ± 12 ng m−3, respectively, were typical. The mean MS/nss‐SO42− ratio ranged from about 0.1 to 0.2. MS and nss‐SO42− concentrations and their variability were roughly comparable to coastal stations at summer. Supported by air mass back trajectory analyses, this finding documented an efficient long‐range transport to Kohnen via the free troposphere. MS/nss‐SO42− ratios exhibited a strong dependence on the MS concentration with systematically higher ratios at higher MS concentrations, a peculiarity which is also evident in a firn core drilled at this site.