Determination of the Rate of Snow Accumulation at the Pole of Relative Inaccessibility, Eastern Antarctica: A Comparison of Glaciological and Isotopic Methods

Abstract

The rate of snow accumulation has been measured at the U.S.S.R. station situated at the Pole of Relative Inaccessibility (eastern Antarctic plateau). Five independent methods were used. The results, expressed in g cm⁻²year⁻¹, are as follows: (1)Accumulation-stake measurements show an accumulation of 3·1±0·5 in 1965. A maximum value of 3·6 for the 6–year interval 1959–65 is derived from snow-thickness measurements. (2)Firn stratigraphy was found difficult to interpret in terms of annual layers. An upper limit of 12 g cm⁻²year⁻¹is suggested. (3)¹⁸O/¹⁶O ratios were measured along the upper 235 cm. Assuming that each maximum in the isotope profile corresponds to a summer season, the accumulation would be 8·6±0·9. (4)Grossβradioactivity as a function of depth was measured on three firn sections. The 1955 radioactive fall-out horizon is clearly marked, enabling the derivation of an average accumulation of 3·0±0·3. (5)The average accumulation over the last 80 years, derived from the²¹⁰Pb distribution with depth, is 3·1±0·3. A multi-annual average accumulation rate of (3·0±0·3) is thus firmly established, as well as the validity of both the²¹⁰Pb method and the 1955 radioactive fall-out horizon method. Stratigraphie studies lead to uncertain results. Oxygen isotope variations give accumulation values which are too high by a factor of two at least.Accumulation values of the same order of magnitude (2·8±0·2) were derived from radioactive fall-out measurements at the U.S. “Plateau” station.