NOAA/WDS Paleoclimatology - Hercules Nèvé, Antarctica 220 Year Ice Core d18O and Accumulation Data

A 42.2 m firn core was collected at the Hercules Nèvé Plateau (100 km inland and 2960 m a.s.l.) in Northern Victoria Land, during the 1994-95 Italian Antarctic Expedition. Chemical (Cl-, NO3-, SO4-2 and H2O2) and isotope (d18O) analyses were performed to evaluate the snow-accumulation rate at this site. Tritium measurements were performed in the upper part of the core in order to narrow down the dating of the core. High nss SO4-2 concentrations seem to be related to some explosive volcanic eruptions, such as Tambora (1815) and the preceding event called "Unknown" (A.D. 1809), Coseguina (A.D. 1835), Makjan (A.D. 1861), Krakatoa (A.D. 1883) and Tarawera (A.D. 1886). A comparison between the seasonal variations observed in the isotope and chemical profiles was carried out in order to reduce the dating uncertainty, using the tritium and the volcanic markers as time constraints. A deposition period of 222 years was thus determined. The 3 year smoothed d18O profile shows more negative values from the bottom of the core (dated A.D. 1770) throughout all the 19th century, suggesting 'cooler' conditions in agreement with other East Antarctic ice-core records. Subsequently, a general increase in d18O values is observed. The calculated average snow-accumulation rates between the above-mentioned time markers are 111-129 kg m-2 a-1.