BELISSIMA
Belgian Ice Sheet – Shelf Ice
Measurements in Antarctica
Field report
30 May 2009
Frank PATTYN, Denis SAMYN1, Jean-Louis TISON
Laboratoire de Glaciologie
Université Libre de Bruxelles
Bryn HUBBARD
Aberystwyth University (UK)
Kenny MATSUOKA
University of Washington (USA)
1
Now at Department of Earth Sciences, University of Uppsala, Sweden
1
2
Contents
1. Project personnel and contact details
2. Introduction
3. Key Dates
4. Field sites
5. Field work
Acknowledgements
3
Project acronyms:
BELISSIMA: BELgian Ice Sheet – Shelf Ice Measurements in Antarctica
4
1. PROJECT PERSONNEL
Frank Pattyn (ULB) – PI
Jean Louis Tison (ULB) – co-PI
Denis Samyn (ULB)
Bryn Hubbard (Aberystwyth University, UK)
Kenichi Matsuoka (University of Washington, USA)
2. INTRODUCTION
This project will investigate the deglaciation and stability of coastal Dronning Maud
Land (DML), East Antarctica. Little is known about timing and magnitudes of
deglaciation in this area. Emerging evidence from West Antarctica indicates that its
contribution to sea level rise since the Last Glacial Maximum (LGM; ~15-20 ka BP) was
much smaller than the previously predicted by rigid-bed ice-sheet models; it is
possible that mass changes in East Antarctica might provide some or all of the missing
freshwater. East Antarctic ice rises, such as Roosevelt Island in the Ross Sea and
Berkner Island in the Weddell Sea, have been used as glaciological dipstick to
establish deglaciation history. This project will investigate a small ice rise at 71°S, 24°E
near the DML coast (Figure 1). This 30 km wide ice rise has a distinct flow divide,
supplying ice to shelves located either side of it.
Focus will also be placed on the dynamics of the ice shelf close to the grounding line
and in rifts, to investigate links between the formation of what is often referred to as
the “ice mélange” in crevasses and fractures and the stability of the ice shelf,
particularly with respect to sub-ice –ocean interactions.
The measurement goals of the project are to: (1) reveal spatial variations of ice
thickness and stratigraphy using ice-penetrating radar; (2) determine and plot ice-flow
vectors using GPS; (3) retrieve ice cores and log boreholes through the ice shelf to
investigate and to sample marine ice inclusions. These data will be used to constrain
following glaciological conditions:
1. Present basal conditions will be examined by subtracting the effects of the radiowave attenuation from the echo intensity associated with the bed.
2. Temporal variations in the spatial accumulation pattern will be retrieved for the
past 500 years using shallow radar layers and the firn cores.
3. Study of ice flow physics, such as higher order effects, and ice/ocean interaction
near grounding lines using radar layers. Melting and refreezing patterns can be
inferred as well.
4. Glaciological history over the past few thousand years will be inferred from the
radar-detected stratigraphy, which contains information about past thickness and
accumulation.
5
5. Marine ice and the “ice mélange” in the vicinity of the grounding line will be
analysed to investigate the role of these inclusions in the stability of the ice-sheet
ice-shelf system.
Results will determine whether the site is suitable for a deep core to establish climate
history over the past ~4,000 years. With the combined expertise in radar methods, ice
core analysis and ice-flow modelling, this project will bring new insight into
interpretation of radar-detected stratigraphy and mechanical properties of the ice in
transition zones at the grounding line, as well as to understand the evolution of the
region through the late Holocene.
3. KEY DATES
Prior to the expedition, the equipment has been tested carefully both in Brussels and
in the field (Tsanfleuron Glacier, Switzerland). Part of the radar equipment was sent
from Seattle (USA) to Brussels and tested completely at the ULB, before it was sent to
Cape Town together with the ULB radar (as a backup system). The drill equipment
consisted of one system owned by ULB and used before in the field as well as a new
ECLIPSE drill from Aberystwyth University, which was completely set up in Brussels
and tested on Tsanfleuron Glacier in October 2008, prior to the departure of the
expedition. The ECLIPSE drilling system that was tested in Switzerland is a modified
version of the Hans-Tausen drill, designed at the University of Copenhagen, Denmark.
The ECLIPSE drill is manufactured in Canada and is intended for drilling dry holes, i.e.
without lubrication liquid, to depths of up to 350m. Despite the design has been
proven at several locations in the Arctic, the version we have at disposal had never
really been tested on the ice. The differential GPS system was also tested during that
occasion. All equipment safely reached Cape Town and was shipped via ALCI to Novo
(Antarctica) and later on to Utsteinen (Princess Elisabeth Station).
Arrival Novo: 22 November 2008
Arrival Utsteinen: 23 November 2008
Arrival equipment on Utsteinen: 24 November 2008
Departure to the field : 28 November 2008
Return to Utsteinen: 15 December 2008
Return to Novo: 20 December 2008
Return to Cape Town: 21 December 2008
4. FIELD SITES
1. Princess Elisabeth Station
24-28 November 2008
i. Radar measurements (ice thickness profile between Pink Shrimp Nunatak
and Utsteinen Ridge)
6
ii. Mass balance measurements: position (differential GPS) and length
measurements of stake network established in 2004 and 2005, which leads
to accurate determination of ice flow speed and surface mass balance
iii. Measurements of surface topography from skidoo with differential GPS to
establish a comparison of 2008 – 2005 surface snow topography and the
effect of the construction of the station on snow drift pattern.
iv. Assemble and test ECLIPSE drill
2. Ice Rumples near ice rise
70°39.331’S, 24°33.583’E
29 November 2008
i. Radar profile across ice rumples to detect whether marine ice in bottom
crevasses is present
3. Rift
70°21.601’S, 24°27.735’E
November – December 2008
i. Radar profile from central part of rift to Roi Baudouin Ice shelf
ii. Detailed radar grid across the transition from the rift to adjacent ice shelf to
examine ice/ocean interactions in the vicinity of the rift system (see Figure 1
for locations)
iii. Ice coring along a longitudinal profile parallel to the long axis of the rift (see
Figure 3 for locations):
 Drill site 1 (camp site, on blown snow drift)
70°21.417’S; 24°27.550’E
 Drill site 2 (in rift, slightly beyond large transverse crevasse)
70°21.242’S, 24°25.626’E
 Drill site 3 (in rift, half way, just passed central berg)
70°20.209’S; 24°13.153’E
 Drill site 4 (in rift, beyond central berg)
70°19.477’S; 24°13.373’E
 Drill site 5 (on ice shelf, upstream of camp site)
70°21.678’S, 24°27.189’E
4. Ice Rise (dome)
70°32.251’S, 24°04.129’E
December 2008
i. Detailed surface topography of central part of dome with differential GPS
ii. Two radar cross profiles (W-E and N-S) across central part of dome to
detect isochronous radar layers. Major profile running from 70°30.871’S,
24°05.413’E to 70°37.258’S, 23°58.213’E.
7
5. Ice Rise (saddle area)
December 2008
i. Radar W-E cross profile from 70°35.852’S, 23°37.652’E to 70°39.910’S,
24°12.901’E
ii. Radar W-E cross profile parallel to previous one from 70°37.517’S,
23°36.533’E to 70°41.123’S, 24°15.095’E
8
5. FIELD WORK
1. Princess Elisabeth Station
Radar and topographic measurements were all analysed and compared to
measurements carried out in 2004 and 2005 prior to the construction of the
station. This led to the submission of the following paper: Pattyn F., K. Matsuoka
and J. Berte (2009) Glacio-meteorological conditions in the vicinity of the Belgian
Princess Elisabeth Station, Antarctica. Submitted to Antarctic Science and accepted
with minor revisions on 18.05.2009. A poster on this subject was presented at the
EGU in Vienna (April 2009). The abstract can be found via the following link:
http://meetingorganizer.copernicus.org/EGU2009/EGU2009-5830.pdf
2. Ice Rise and rift radar survey
All radar profiles have been corrected for elevation changes with the differential
GPS data. In all profiles the bedrock signal is clearly identified, as well as several
distinct internal reflectors, which can be considered as isochrones. A preliminary
analysis reveals that effectively a Raymond bump (local upwarping of internal
layers in the ice due to the specific ice flow dynamics of an ice divide) exists under
the ice divide of the ice rise, which points to a relative longstanding stability of the
ice flow pattern in this area. Internal reflectors/layers are identified to depths of
400m below the surface, which in view of the local accumulation rates should
reveal the accumulation history of the last 1000-2000 years. Further analysis will
include identification of the different internal reflectors for reconstructing the
accumulation history and ice flow dynamics as well as analysis of the bedrock
reflector intensity and phase (Figures 1 and 2).
9
Figure 1: Location map with radar profiles across the ice rise, the ice shelf and the rift.
Figure 2: Radar profile across the ice rise and onto the ice shelf. Note the presence of
Raymond bumps under the ice divide (K. Matsuoka, University of Washington).
10
3. Ice Shelf and rift ice core drilling
Figure 3 shows the approximate location of each drilling site, with associated
characteristics of the ice encountered.
Figure 3: Position of the drill sites in and around the rift of the Roi Baudouin ice
shelf.
A total thickness of 95 meters of ice cores has been recovered from firn, meteoric
ice and marine ice (ice formed in the ocean, below the ice shelf). The ECLIPSE drill
has been used down to about 39 m at site 1, within firn and ice forming as a
“wedge” on the rift’s cliff, and providing lateral access to the bottom of the rift.
Sea water infiltration started at about 27 meters, and resulted in a slow
deterioration of the drill’s working, since the ECLIPSE is designed for drilling only
in dry conditions. Drilling halted completely at 39 meters depth, passing through
the firn to ice transition.
The backup Belgian SPIRE-based electro-mechanical drill was then used for sites 2
to 4, while the ECLIPSE drill was repaired. The ECLIPSE drill was once used again at
the end of the field season at site 5, to penetrate the surface of the ice shelf
upstream of the camp site, down to about 15 meters.
Sites 2 to 4 were located within the rift itself, roughly along an East-West transect.
Drilling at site 2 went through firn and ice before high concentration of slush from
11
the drilling chips hampered recovery of the ice cores. At site 3, more than 8
meters of marine ice (easily recognized by its translucent bubble-free aspect, were
recovered before entering a 2 meter layer of loosely bounded ice crystals, difficult
to retrieve with the drill. Finally, at site 4, marine ice was found from the very top,
with a thickness of nearly 13 meters, and underlain again by loosely bounded
crystals (Figure 4 and 5). There, the ice water interface has been reached, although
visual inspection using the Aberystwyth televiewer down the hole testified the
existence of several meters of loose ice crystals, freely floating within the ocean
water.
Figure 4: Left: transition from meteoric ice to marine ice at Site 3; Right: loose
crystals of frazil accumulating at the ice-water interface from Site 4
This is a fundamental discovery, since the presence of marine ice indicates
vigorous ice-ocean interactions involving an active Deep Thermohaline Circulation
below the ice shelf, as was shown to exist under several other larger Antarctic ice
shelves (Filchner-Ronne, Ross, Amery, Nansen, …). Our ice cores, along with the
televiewer images, therefore provide direct evidence for the first time of marine
ice contributing contributes, as part of the “ice mélange” (a mixture of blown
snow, firn, fallen ice blocks, sea ice and marine ice that fills rifts and crevasses
forming in ice shelves), to the potential stabilization of this floating ice body.
12
Figure 5: Televiewer image of the ice mélange
The ice cores are now back at the ULB laboratory, and will be studied for their
physico-chemical properties and the impact of those properties on the ice's
rheological properties. Particular emphasis will be placed on comparing the
fundamental ice types present: marine ice, meteoric ice and firn.
Acknowledgements
We wish to thank all participants of the BELARE expedition that kindly assisted us in
the field: Alain Hubert (field leader), René Wagemans (base camp manager and
backup field assistant), Kristof Soete en Jesko Kaczynski (mechanics and field
assistants), Nathalie Pattyn (MD and part-time base camp manager and GPS
assistant), and all others present at the time of our visit at Princess Elisabeth Station,
who made our stay as comfortable as possible. Kenichi Matsuoka was partly
supported by a University of Washington Royalty Research Fund.
13