DISTRIBUTION OF STABLE ISOTOPES IN SURFACE SNOW ALONG THE ROUTE OF THE 1990 INTERNATIONAL TRANS-ANTARCTICA EXPEDITION

This paper presents the distribution of average deltaD and deltaO-18 v alues for the top 1 m of surface snow for a large area of Antarctica. The samples were collected on the 1990 International Trans-Antarctica Expedition which crossed the continent from the northern tip of the An tarctic Peninsula to Mirny Station. The empirical relationships betwee n the isotopes, temperature and elevation are computed. The slopes of deltaD with respect to the surface temperature for the segments west ( Patriot Hills-Vostok) and east of Vostok (Komsomolskaya-Mirny) are not significantly different to that observed between Dumont d'Urville and Dome C (Lorius and Merlivat, 1977) which are often used to interpret deep ice-core isotopic profiles. There is, however, a noticeable shift between the two regression lines with, for a given temperature higher isotopic values west of Vostok. The deuterium excess values (d = delt aD - 8 x deltaO-18) increase sharply at 3000 m a.s.l. on the plateau, confirming the results of Petit and others (1991).