Paleoclimate studies on Antarctic blue ice fields with ground penetrating radar
Leader: John Moore Start of the project: 2005
Research group: Global change End of the project: 2008
The project is funded by Academy of Finland.
|The blue ice fields of Antarctica can have hundreds of thousands of years old ice on their surfaces. There are no similar places anywhere else on Earth. The old ice has preserved within it information about the Earth’s climate history, but the age of this ice is very difficult to estimate. The dynamics and the response to the climate change of the blue ice areas are also still largely unknown.
We have spent many seasons of work on various blue ice areas in Dronning Maud Land and in West Antarctica (courtesy of co-operation with University of Maine and USAP logistics). The best studies of these areas is Scharffenbergbotnen, about 200 km south of the Finnish station of Aboa. In 2006/7 we a extracted 2.6 km long section of ice for detailed chemical and isotopic analysis. The blog of the expedition is here .
50MHz radar profiling in Antarctica.
Photo: John Moore
The main goals of the research are:
1. To develop dating methods for the surface ice in the Antarctic blue ice areas using ground penetrating radar, conductivity and GPS measurements, by computer modeling and by chemical analysis of ice samples.
2. To make paleoclimatic interpretation from the surface ice samples.
3. To supplement the mass balance research of Antarctica
4. To determine how the Antarctic blue ice areas respond to the changes in climate.
During the 2003/2004 field season the group concentrated on one of these areas and retrieved a 100-m long horizontal ice core (SBB1H). The team has analyzed it for its ionic composition and Dutch colleagues at the Centre for Isotope Research (Groningen,NL) have analyzed its oxygen isotopes. These measurements indicate that the surface age is considerably younger than what steady state modeling predicts. The team also found evidence for well preserved annual cycles.
|Based on the earlier results the aim of the 2006/7 season was to extract a horizontal ice core, which spans approximately 20 000 years. This is exciting for several reasons. Firstly, this ice core would be the first Antarctic ice core record of the glacial/Holocene transition with annual resolution. Secondly, the difference between the observed age relationship and modeled steady state relationship will tell about the past stability of Antarctic ice sheet.
Key elements of the research so far have been:
• The development of a novel flowline model suitable for blue ice studies
• Interpretation of radar internal reflectors for mass balance purposes
• Methods of dating blue by combined modeling and stratigraphic matching to ice cores
Interpretation of blue ice Holocene dynamics and isotopic signatures: Sinisalo et al., J- Glaciol. in press, and Anna Sinisalo’s PhD thesis to be defended late 2007.
Photo: John Moore
PDFs of all these publications and others from the group are available here .
• Grinsted, A., J. C. Moore, V. Spikes and A. Sinisalo. 2003. Dating Antarctic Blue Ice Areas using a Novel Ice Flow Model. Geoph. Res. Lett., Vol. 30, No. 19, 2005 10.1029/2003GL017957.
• Sinisalo, A., A. Grinsted, and J. Moore (accepted). Scharffenbergbotnen blue ice area dynamics, Ann. Glac. 39.
• Sinisalo, A., A. Grinsted, J. Moore, E. Kärkäs and R. Petterson, 2003. Snow accumulation studies in Antarctica with ground penetrating radar using 50, 100 and 800 MHz antenna frequencies. Ann. Glac. 37.
• Sinisalo, A., J. Moore, R. van de Wal, R. Bintanja and S. Jonsson, 2003. A 14-year mass balance record of a blue ice area in Antarctica. Ann. Glac. 37.
Senior Scientist John Moore
Arctic Centre, University of Lapland
Tel: + 358 16 341 2757 / +358-40-5007775
Scientist Aslak Grinsted Arctic Centre, University of Lapland
Scientist Kristiina Virkkunen Arctic Centre, University of Lapland
The blog of expedition