Aerosol concentration at Kohnen station in south summer 2000, 2001 and 2002

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-[SO4]2-) concentrations of 353 ± 100 ng/m3 and 320 ± 250 ng/m3, as well as methane sulfonate (MS) concentrations of 59 ± 36 ng/m3 and 74 ± 80 ng/m3, respectively. For the summer campaign in 2001, significantly lower nss-[SO4]2- and MS levels of 164 ± 150 ng/m3 and 19 ± 12 ng/m3, respectively, were typical. The mean MS/nss-[SO4]2- ratio ranged from about 0.1 to 0.2. MS and nss-[SO4]2- 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-[SO4]2- 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.