Spatial gradients in snow layering and 10 m temperatures at two EPICA-Dronning Maud Land (Antarctica) pre-site-survey drill sites

Annals of Glaciology, Vol. 30, p. 13-19, 2000 

P. Holmlund, M. Nyman, R. Pettersson, M. Stenberg
Department of Physical Geography, Stockholm University, S-106 91 Stockholm, Sweden.
K. Gjerde
Norwegian Mapping Authority, Kartverksvegen 21, N-3500 Hönefoss, Norway.
N. Gundestrup
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen.
M. Hansson
Department of Meteorology, Stockholm University, S-106 91 Stockholm, Sweden.
E. Isaksson, L. Karlöf, J.-G. Winther
Norwegian Polar Institute, Polarmiljøsenteret, N-9296 Tromsø, Norway.
F. Pinglot
Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS BP 96, 38402 Saint-Martin-d'Hères Cedex, France.
C.H. Reijmer, M. Thomassen, R. van de Wal, C. van der Veen
Institute for Marine and Atmospheric Research Utrecht, (IMAU), University of Utrecht, NL-3508 CC Utrecht, The Netherlands.
F. Wilhelms
Alfred-Wegener-Institut für Polar- und Meeresforschung, Postfach 120161, D-27515 Bremerhaven, Germany.

During the 1997/98 field season, Sweden, Norway and The Netherlands performed a pre-site survey for EPICA in Dronning Maud Land, Antarctica. This paper summarizes the results and pays special attention to the high spatial gradients found in snow layering and temperatures. The sites were "Camp Victoria" (CV) on Amundsenisen (76oS, 8oW; 2400 m a.s.l.), approximately 550 km from the coast, and "Camp Maudheimvidda" (CM) on Maudheimvidda (74oS, 13oW; 362 m a.s.l.), some 140 km from the coast.
The drilling programme included both medium-long firn/ice cores and shallow firn cores. These were analysed by means of d18O, DEP, ECM, b activity, density, and ion content. The combined results suggests a mean annual accumulation rate of 60 mm.w.e. for CV and 220 mm.w.e. for CM.
Variability measurements of spatial snow layering were performed at two scales; over tens of kilometres by radar and over a few metres by pits and high-resolution radar soundings. Results, as measured by relative standard deviation, were typically 10% on the polar plateau and as high as 50% near the coast.
The 10 m temperature measurements were -38.5oC (std dev. = 0.5o) for CV and -17.6oC (std dev. = 0.15o) for CM.
Snow chemistry was sampled at each medium-long-core drill site. Comparison of d18O profiles from snow pits and the uppermost part of the CV medium-long core showed large variations. Mean d18O values over 2 m profiles varied between 41.6‰ and 39.7‰ within a horizontal distance of 50 m.