A 200 year sulfate record from 16 Antarctic ice cores and associations with Southern Ocean sea-ice extent

Abstract

Chemistry data from 16, 50-115m deep, sub-annually dated ice cores are used to investigate spatial and temporal concentration variability of sea-salt (ss) SO42- and excess (xs) SO42- over West Antarctica and the South Pole for the last 200 years. Low-elevation ice-core sites in western West Antarctica contain higher concentrations of SO42- as a result of cyclogenesis over the Ross Ice Shelf and proximity to the Ross Sea Polynya. Linear correlation analysis of 15 West Antarctic ice-core SO42- time series demonstrates that at several sites concentrations of ssSO42- are higher when sea-ice extent (SIE) is greater, and the inverse for xsSO42-. Concentrations of xsSO42- from the South Pole site (East Antarctica) are associated with SIE from the Weddell region, and West Antarctic xsSO42- concentrations are associated with SIE from the Bellingshausen-Amundsen-Ross region. The only notable rise of the last 200 years in xsSO42-, around 1940, is not related to SIE fluctuations and is most likely a result of increased xsSO42- production in the mid-low latitudes and/or an increase in transport efficiency from the mid-low latitudes to central West Antarctica. These high-resolution records show that the source types and source areas Of ssSO42- and xsSO42- delivered to eastern and western West Antarctica and the South Pole differ from site to site but can best be resolved using records from spatial ice-core arrays such as the International Trans-Antarctic Scientific Expedition (ITASE).