International Polar Year 2007–2008 - WMO

questions and plans to enter and sample subglacial
environments. Critical issues that surfaced were the
cleanliness of these experiments and the need for
long-term stewardship of subglacial lakes as sites of
scientific and public interest. A U.S. National Academies
committee reviewed plans for subglacial lake
exploration from the perspective of environmental
protection and conservation. This review and subsequent
international acceptance of major findings has
set standards for conducting future subglacial aquatic
environment study and exploration (U.S. National Research
Council, 2007).
Studies of Lake Vostok during IPY
Russian exploration at Lake Vostok continued as
part of the drilling program within the framework
of the long-term Federal Targeted Program “World
Ocean”, subprogram “Antarctica.” It was implemented
by a consortium of eight Russian research institutions
led by the Arctic and Antarctic Research Institute
(AARI) of Roshydromet. In the framework of this
program, the Polar Marine Geological Research
Expedition (PMGRE) and Russian Antarctic Expedition
(RAE) have performed extensive geophysical surveys
of the Lake Vostok area and its vicinity by means
of ground-based radio-echo sounding (RES) and
reflection seismic measurements (Masolov et al.,
2006; Popov et al., 2006, 2007; Popov and Masolov,
2007). The overall length of the geophysical traverses
completed in February 2009 exceeded 6000 km and
included 320 seismic measurements (Fig. 2.6-3). The
main output of this large-scale field activity was a
series of 1:1,000,000 maps of the Lake Vostok water
table limits, the ice and water body thickness, the
bedrock relief, its geomorphological zones and the
spatial pattern of the internal layers in the overlying
ice sheet. While a handful of geophysical transects,
involving radio-echo sounding, were acquired over
Lake Vostok between 1971-1972 and 1974-1975, it was
more than twenty years before the first systematic
survey of the lake by Italian geophysicists occurred in
1999. In the Austral season of 1999-2000, twelve new
radio-echo sounding transects were collected over
the lake, including one continuous flight across the
long axis of the lake. From these data, the lake extent
was better understood (to be ~260 km by 80 km)
and the steady inclination of the ice-water interface
was reconfirmed along the entire length of the lake
(Kapitsa et al., 1996). The investigation also revealed
the relatively high topography on either side of the
lake showing that the lake occupies a deep trough.
A year later, U.S. geophysicists undertook what still
remains the definitive survey of the lake by airborne
measurements (Studinger et al., 2003). More than
20,000 line-km of aerogeophysical data were acquired
over an area 160 by 330 km, augmented by 12 regional
lines, extending outside of the main grid by between
180 and 440 km. The outcome was the first detailed
assessment of the lake and its glaciological locale.
Gravity modelling of the lake bathymetry established
the existence of two basins (Studinger et al., 2004).
The southern basin of the lake is more than 1 km deep.
These geophysical investigations supplemented the
long-standing geophysical campaigns by Russian
scientists from 1995-2008 and resulted in 318 seismic
reflection soundings and 5190 km of radio-echo
soundings (Masolov et al., 2001, 2006).
During IPY, geophysical, geodetic and glaciological
traverse programs carried out by RAE focused on
investigating the two ice-flow lines starting at Ridge
B, the Vostok flow line (VFL) passing through drilling
site 5G at Vostok Station and the North-Vostok flow
line (NVFL) crossing the northern part of Lake Vostok
(Fig. 2.6-3). These ground traverses were planned and
implemented under the IPY TASTE IDEA (Trans-Antarctic
Scientific Traverses Expeditions – Ice Divide of
East Antarctica) project, as part of the Italian/French/
Russian traverse from Talos Dome, via Dome C, Vostok
and Dome B to Dome A. The data collected in the
field were used to constrain a thermo-mechanical
ice-flow line model (Richter et al., 2008; Salamatin et
al., 2009; Popov et al., submitted). Coordinated field
and modeling efforts yielded an improved glaciological
timescale for the 5G ice core and refined the
isotope-temperature transfer functions for converting
isotope and borehole temperature data from Vostok
into a palaeo-temperature record (Salamatin et al.,
2009). Other important outputs of the “Vostok ice flow
lines” project were more accurate model estimates of
the contemporary distribution of the accreted (lake)
ice thickness and freezing rates along the Vostok
flow line. In addition, ice age-depth and temperature
profiles and the basal melt-rate were predicted for
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