A detailed study of snow accumulation and stable isotope content in Dome C (Antarctica)

Abstract

Snow samples have been taken in the Dome C area in order to study the variations of the accumulation rate and of the stable isotope content over the last century. Stake observations indicate a large spatial variability of the accumulation rate at a 1‐year scale (σs = 2.6 g cm−2 yr−1 for a mean value ā = 3.6 g cm−2 yr−1). The depth of the 1965 and 1955 layers determined from beta radioactivity measurements in 19 sites lets us deduce that the spatial variability becomes small at a 10‐year scale (σs = 0.3 g cm−2 yr−1), showing that the snow collected at one point is well representative of the fallen precipitation over this period. The rate of snow accumulation since 1965 is about 30% higher than during the 1955–1965 period. This conclusion is supported by measurements over a large geographical sector of East Antarctica. Shorter‐term changes of the snow accumulation have been studied by various means and in particular from detailed deuterium content profiles; by comparing with the beta and tritium radioactivity determinations it is shown that the deuterium variations do not allow us to obtain a seasonal record. In such a low‐accumulation area, different mechanisms (such as smoothing of the isotopic signal, roughness of the surface, irregularity of the accumulation) which may disturb the short‐term record are discussed. The interpretation of stratigraphie observations is not straightforward. However, it was possible to obtain a calibration down to the 1955 layer, which allows us to offer a dating of the snow layers over the last century. The mean accumulation so obtained (3.7 g cm−2 yr−1) is in good agreement with the value (3.6±0.5) deduced from lead 210 measurements. Geographical changes of the mean deuterium content are relatively small, showing that at a 10‐year scale the isotopic signal is well representative of the mean deuterium content of the precipitation. This ensures that the smoothed (10‐year running mean values) deuterium profile obtained over the last 160 years provides a good indication of the temperature secular trend in the Dome C area.

Accumulation distribution in terre adélie, antarctica: effect of meteorological parameters

“…For Dome C, it corresponds to the mean value of 22 ice cores sampled over a few kilometers. Some of these results have already been published (Lorius and others, 1970;Lambert and others, 1977;Petit and others, 1982;Pourchet and others, 1983) and complementary profiles available are given here ( Fig. 2a and b).…”

Development and calibration of an automatic spectral albedometer to estimate near-surface snow SSA time series

“…Despite the proximity and a slight partial overlap of the footprints, differences between the two heads can be particularly marked as in Spring 2014. We could invoke the fact that snow accumulation is irregular at Dome C (Petit et al, 1982;Libois et al, 2014a), leading to irregular deposition on the surface. However, this argument is not compatible with the absence of difference observed during the summers although several precipitation events occurred and had a clear effect on the observed SSA (Libois et al, 2015) but did not lead to differences between both heads.…”

Archival processes of the water stable isotope signal in East Antarctic ice cores

“…Table 1. Climatic conditions at the different sites used in this study (Alley, 1980;Petit et al, 1982;Wendler and Kodama, 1984;Oerter et al, 2000;Ekaykin et al, 2002;van As et al, 2007;Lazzara et al, 2012;Casey et al, 2014;Genthon et al, 2015;Touzeau et al, 2016;Laepple et al, 2016) Site Table 2). Because different teams were in charge of the different sampling activities, the protocols differ between the years.…”