Decadal timescale links between Antarctic Peninsula ice-core oxygen-18, deuterium and temperature

The Antarctic Peninsula region has exprienced a long-term warming trend over the twentieth century, with the 1971-90 mean at Faraday being 1.9°C warmer than the mean over 1903-41 based on expedition reports. For the period prior to 1900, there is conflicting evidence from different data sources. An initial interpretation of isotopic data from ice cores suggests that the nineteenth century was warmer than the twentieth century. In contrast, snow accumulation rate data for the nineteenth century from the same ice cores suggest lower temperatures. Here we investigate these facts by studying the links between atmospheric temperature over the Antarctic Peninsula, circulation parameters and isotopic data over the period of instrumental records. We show that the relationships between these variables are complex and highly spatially variable. In particular, the correlations between temperature and d 18O and dD are generally of the order r = 0.5 or less on timescales of one to five years. Conflicts between evidence from accumulation rate and isotopic data appear to reflect the influence of source-region effects on the isotope records. To unravel the complex isotopic records available for the Peninsula region better; additional cores must be analysed for both d 18O and 8D at the same site

Distribution and fall-out of 137Cs and other radionuclides over Antarctica

International audienceAbstract This article aims to give a comprehensive view of the distribution patterns for natural and artifical radionuclides over Antarctica. We focus this study on 137 Cs, 210 Pb and tritium. Applying various statistical methods, we show that the deposition of radionuclides reveals a structured distribution, although local drift redistribution and the snow-surface roughness disturb the representativeness of samples and produce a “noise” effect. The deposition of 137 Cs over Antarctica (885 TBq) represents 0.09% of the total deposition of this radionuclide in the world and the correlation between 137 Cs fluxes and accumulation shows two sub-populations. For the stations with a mean annual temperature above −21° C, a strong correlation is found, whereas the correlation is lower for locations with temperatures below −21° C. The flux of 210 Pb varies from 0.9 to 8.2 Bq m −1 a − 1 with values strongly correlated with the accumulation and a well-defined spatial structure. The same mechanism governs the deposition of artificial and natural tritium but it clearly differs from that of other radionuclides associated with particulate material. The “dry fall-out” accounts for between 60 and 80% of the total fall-out for the artificial radionuclides and around 40% for 210 Pb. This difference is likely related to a tropospheric fraction for 210 Pb. Despite its isolated location, the radioactive fall-out of artificial long-lived radionuclides over Antarctica has been ten times greater than for natural radionuclides