NOAA/WDS Paleoclimatology - Amundsenisen Dronning Maud Land oxygen isotope and accumulation rate data from 1895-1996 CE

STUDY NOTES: DML data contributed to the PAGES 2k project Provided Keywords: oxygen isotope of water, temperature proxy, accumulation rate
ABSTRACT SUPPLIED BY ORIGINATOR: The paper focuses on studies of snow-pit samples and shallow firn cores taken during the 1995–96 and 1996–97 field seasons at Amundsenisen, Dronning Maud Land, Antarctica. The dating of the firn is based on the artificial tritium distribution in the snow cover and on several reference horizons identified by electrical measurements. The early 1964 through 1965 horizon is marked by the deposition of sulfate released to the atmosphere during the eruption of the Agung volcano in March 1963; this horizon was detected by dielectric profiling and electrical conductivity measurements; the proof by chemical analysis has still to be seen. At the ten investigated sites on Amundsenisen the 1964–65 horizon was identified 4.1–5.7 m below the surface. The accumulation rates on Amundsenisen are 41–91 kg m-2a-1. The cores are up to 100 years old. A relationship between isotope content and the mean air temperature on a regional scale can be based on measurements of firn temperature at 10 m depth at the drilling sites. Between Neumayer station at the coast and Heimefrontfjella, the temperature gradient of the deuterium content is 9.6‰ K-1. South of Heimefrontfjella, on the Amundsenisen plateau, it is only 5.5‰ K-1. Time series of yearly accumulation rates show no significant trend. For the isotope records a significant trend to higher values with gradients of 0.1–0.2 ?2H‰a-1 can be seen in five of the ten time series.