Russia National Report Prepared by: Volodya Lipenkov
Arctic and Antarctic Research Institute, St. Petersburg
Oversnow traverses in the Lake Vostok area
Over the past five years (1999-2004) Russian ITASE fieldwork has been carried out in the vicinity of Vostok Station and in the Lake Vostok area in conjunction with remote (radio-echo and seismic) surveys of subglacial Lake Vostok. The total length of the geophysical profiles completed by 2004 exceeds 3000 km. Snow pit works performed along the traverse routes allowed investigation of the spatial variability of isotope composition and accumulation of snow over the whole lake area and the high-resolution mapping of these properties in the southern part of the lake.
samples have been collected in 3 to 12 m pits (spanning 50 to 250
years) located within 3-4 km from the Vostok Station. Collected
samples have been analyzed for gross ß-radioactivity, liquid
electrical conductivity, stable isotopes (δ18O,
D), major ion chemistry, and microbiological particles. The work
has been carried out in collaboration with French scientists from
LGGE (Grenoble) and LSCE (Saclay). The main objectives of this study
are to reconstruct high-resolution local temperature and accumulation
histories covering the past 200-250 years and to refine paleoclimatic
interpretation of the deep ice core data using a direct comparison
of the isotope composition of the upper snow and the 42-year instrumental
records from Vostok Station.
Eight high-resolution annual records of accumulation and isotope composition of snow covering the period from 1940 to 1999 and two records covering the period from 1770 to 1999 have been obtained. The records have been interpreted in terms of past temperature and accumulation rate. The calibration is based on the meteorological, balloon-sounding and synoptic records that have been acquired at the Vostok Station (1958-2000), 16 temperature profiles measured between 1961 and 1990 in four dry holes, the data on spatial and temporal variations in isotope composition and accumulation of snow obtained at a stake farm 2 km apart from Vostok, and the data on isotope composition of precipitating and blowing snow collected at the station throughout the year 2000.
The reconstruction suggests that snow accumulation rate and the near-surface air temperature at Vostok have been changing during the past 200 years between 1.5 and 3 g cm-2 year-1, and between -57 and -55 °C, respectively, with a slight general tendency to increase from the past to the present. Both parameters reveal a 50-year periodicity that correlates with the Pacific Decadal Oscillation index, implying a climatic teleconnection between the central Antarctica and the tropical Pacific.
Planned work (2004 – 2006)
Glaciological investigations along the ice flow line passing through Vostok Station are planned. The 400 km long traverse route will follow the Vostok flow line from Ridge B to Vostok Station (about 300 km) and continue to 100 km downstream of the station to reach the area with well developed megadunes to the south of Vostok. The main objectives of the traverse program are:
- To determine spatial and temporal (over the past 200 years) variability of accumulation rate, stable isotope, and chemical composition of Antarctic snow along the Vostok flow line.
- To determine the ice-sheet thickness and bottom conditions, ice-surface and subglacial topography, as well as to trace the internal layers and to determine the modern ice-flow velocity vectors along the traverse route.
The proposed traverse program includes shallow (to 30 m) drilling
with firn core retrieval at 25-50 km interval along the traverse
route. It is planned that a standardized suite of firn core properties
recommended for ITASE ground-based sampling programs will be obtained.
Estimates of the average accumulation rate will be made on the basis
of ECM (Tambora layer detection) and gamma-ray or/and beta (1954-1965
bomb test layers) methods. Annually resolved records of snow accumulation
and isotope composition (δ18O, δD and deuterium
excess) will be obtained at 50-100 km interval using visible stratigraphic
layering and the dating tools described above.
The geophysical program will include radar-echo sounding and seismic measurements, as well as determination of ice flow vectors based on GPS measurements.
The implementation of the traverse is currently scheduled for 2004-05 or/and 2005-06 and 2006-07 Antarctic field seasons. The traverse is considered to be part of the planed Talos Dome – Dome C – Vostok – Dome A ITASE traverse in the frame of International Polar Year (http://www-lgge.obs.ujf-grenoble.fr/axes/IPY/).
Most recent ITASE related publications
Ekaykin A.A., Lipenkov V.Ya., N.I. Barkov N.I., Petit .J.R., Masson-Delmotte V. Spatial and temporal variability in isotope composition of recent snow in the vicinity of Vostok Station: Implications for ice-core record interpretation. Ann. Glaciol., 35, 2002, 181-186.
Ekaykin A.A., Lipenkov V.Ya., Kuzmina I.N., Petit J.R., Masson-Delmotte V, Johnsen S.J. The changes in isotope composition and accumulation of snow at Vostok Station over the past 200 years. Ann. Glaciol., 39, in press.
Ekaykin A.A. Meteorological regime of central Antarctica and its role in the formation of isotope composition of snow thickness. – Thèse de l’Université Joseph Fourier, Grenoble, et de la Faculté de Géographie de Saint Pétersbourg (Russie), 2003. – 123 p. (available at http://www-lgge.obs.ujf-grenoble.fr/publiscience/theses/theses.shtml).