26 Science Highlights: Ice Core Science

As in , the high accumula- fort. WAIS Divide is under the um- Year (2007-2008). Bottom-up, indi- tion rate and great ice thickness will brella of the recently established vidual investigator-driven interna- permit high-confidence borehole International Partnerships for Ice tional collaborations on WAIS Divide thermometry-based temperature Coring Science (IPICS), although its are highly encouraged, although no estimates for the past glacial pe- planning long predates IPICS. WAIS formal, top-down structure for col- riod. Other Antarctic borehole ther- Divide is one of the fi rst elements laboration has been imposed. mometry efforts have been stymied to get underway in the IPICS 40,000 by the low accumulation rate. WAIS Year Network, which will map spa- REFERENCES Divide should provide the fi rst reli- tial variation at the regional scale in Brook, E.J., White, J.W.C., Schilla, A.S.M., Bender, M.L., Barnett, B., Severinghaus, J.P., Taylor, K.C., able direct temperature estimate of order to better understand the dy- Alley, R.B., Steig, E.J., 2005: Timing of millennial- the last glacial maximum in Antarc- namics of the last deglaciation (see scale climate change at Siple Dome, West Ant- tica. Other borehole logging (optical, Brook, this issue). The importance arctica, during the last glacial period, Quaternary Science Reviews, 24: 1333-1343. sonic) will place unique constraints of spatial differences between cores Taylor, K.C., White, J.W.C. Severinghaus, J.P., Brook, on ice deformation, which combined within has been high- E.J., Mayewski, P.A., Alley, R.B., Steig, E.J., Spen- with accurate surface temperature lighted recently by the Siple Dome cer, M.K., Meyerson, E., Meese, D.A., Lamorey, G.W., Grachev, A., Gow, A.J. and Barnett, B.A., history, timescale, and accumulation record (Taylor et al., 2004). Improved 2004: Abrupt climate change around 22 ka on the rate, will make a potent synergy for understanding of regional variations Siple Coast of Antarctica, Quat. Sci. Rev., 23: 7-15. glaciological modeling of the history in climate during the past 100 kyr Severinghaus, J.P., Grachev, A., Luz, B., and Caillon, N., A, 2003: method for precise measurement of of the WAIS. This effort will address will help separate global from re- argon 40/36 and krypton/argon ratios in trapped questions about the stability of this gional signals. air in polar ice with applications to past fi rn thick- marine-based ice sheet, which would International collaboration has ness and abrupt climate change in Greenland and at Siple Dome, Antarctica, Geochim. Cosmochim. raise sea level 5 m if melted. already greatly aided the DISC deep Acta, 67: 325-343. drill development, and it is antici- Wider perspectives of the WAIS pated that international partnerships project on WAIS Divide drilling and science International collaboration fi gures will continue at a heightened pace in prominently in the WAIS Divide ef- the context of the International Polar

International Trans Antarctic Scientifi c Expedition (ITASE)

PAUL ANDREW MAYEWSKI Climate Change Institute, University of Maine, Orono, USA; [email protected]

Introduction ITASE has as its primary aim the collection and interpretation of a continent-wide array of envi- ronmental parameters (Fig. 1), assembled through the coordi- nated efforts of scientists from 20 nations. ITASE offers the ground- based opportunities of traditional style traverse travel, coupled with the modern technology of GPS, crevasse detecting radar, satellite communications and multi-disci- plinary research (Fig. 2). By oper- ating predominantly in the mode of an oversnow traverse, ITASE offers scientists the opportunity to experience the dynamic range of the Antarctic environment. The combination of disciplines represented by ITASE provides a unique, multi-dimensional (x, y, Fig. 1: ITASE national traverse routes superimposed on RADARSAT image. Solid lines repre- z and time) view of the ice sheet sent completed traverses, dashed represent proposed or planned traverses. and its history. As of 2004, ITASE 7000 m), remotely penetrated Results has completed >20,000 km of to ~4000 m into the ice sheet, Although full-scale reconstruc- snow radar, recovered more than and sampled the atmosphere to tions of past climate over Ant- 240 firn/ice cores (total depth heights of >20 km. arctica have yet to be fi nalized,

PAGES NEWS, VOL.14, N°1, APRIL 2006 Science Highlights: Ice Core Science 27

Ice topography Outlook Shallow radar coverage US-ITASE Core Site (70-100 m) Ice sheet Mass balance site (schematic) Field measurements including new Ice velocity vector (schematic) Deep radar internal techniques, e.g. Lidar and airborne Cartoon of 3D ice surface reflectors Summer air/snow temperature profile topography surveyed Site 01-3 Bedrock reflector Winter snow temperature profile for ice dynamics & 8.5 m/yr coherent GPR, laboratory ice fl ow mass balance Site 01-1 1620 200 yrs 1830 studies, new computer modeling Ice Surface 1610 (from GPS) 1840 5 m/yr techniques, including new remote Shallow radar 200 yrs ice core & 1600 snow pit up 1810 sensing techniques, e.g. Satellite to 0.12 km Continuous shallow Elevation (m) 1590 Radar (SAR) interferometry, all 200x Vertical radar coverage to 1800 exaggeration 120 m depth between -4 -2 0 2 4 ice core sites -4 -2 0 2 4 contribute to ISMASS and ITASE Distance (km) Distance (km) Ice surface (from GPS) goals. The extensive use along 1000 ITASE traverses of new techniques

GPS-derived ice topography 0 like GPR and GPS, integrated with and deep radar interpretation 17,500 yr. Isochrone core data, provide detailed informa-

up to 3.2 km Elevation (m) -1000 dated from Byrd Deep Core (Blunier and Brook, 2001) Bedrock tion on surface mass balance. Some -2000 20x Vertical exaggeration GPR layers have been surveyed 200 300 400 A Distance (km) B extensively throughout Antarctica Fig. 2: Multi-dimensional approach to the multi-disciplinary ITASE objectives. Studies at a and they can be used as historical variety of spatial scales extending from the subglacial bedrock to the surface. Ice core sites along each traverse route produce 200-1000+ year annually dated climate records. Ice core benchmarks to study past accumu- site selection is determined by fi eld interpretation of shallow radar data. Numerous measure- lation rates. In addition, coupling ments are made at each core site to provide context for the ice core climate records. These ground survey data with satellite- measurements include: high-resolution surface topography maps; snow pit measurements of density, chemistry, stable isotopes, temperature; and meteorological data. Ice mass balance based observations provides new and horizontal velocity studies located 200 years upstream provide past ice fl ow history for the tools for measuring, for example, ice cores. Shallow and deep-penetrating radio echo sounding data tie the ice cores together and ice surface velocity and ice sheet provide large-scale context for ITASE cores and future deep ice core climate records. Internal stratigraphy in both radio echo sounding records represents isochronal events, and a record surface temperature. of depositional and ice fl ow history along the traverse. The radar data and interpretation, and The growing ITASE database ice topography along the radar profi les shown here are actual examples of the 2001 US-ITASE has the potential to explore tem- season. Figure by Brian Welch, St. Olaf College, US ITASE. poral variability and recent evolu- ITASE has pioneered calibration cused on understanding the fac- tion of Antarctic climate, utilizing tools, reconstruction of climate tors that control climate variability an unprecedented spatio-temporal indices, and evidence for climate over Antarctica and the Southern array. Data extraction and valida- forcing, using single-sites through Ocean. tion activities are an essential pre- to multiple arrays of sites. Initial Understanding the distribution liminary to the synthesis task. Such syntheses of combined ITASE and of snow precipitation over the Ant- activities, together with the devel- deep ice core records demonstrate arctic continent, and the surface opment of instrumental calibration that inclusion of instrumentally processes on different spatial and techniques, have been a signifi cant calibrated ITASE ice core records temporal scales that redistribute component of ITASE studies. Maps allows the previously unavailable this precipitation, is the area of of surface distribution of chemi- reconstruction of past regional greatest common interest be- cal species (Bertler et al., in press) to continental scale variability in tween ITASE and another SCAR indicate the unprecedented scope atmospheric circulation and tem- (Scientifi c Committee on Antarctic for exploring climate variability as perature. Emerging results dem- Research) activity, Ice Sheet Mass onstrate the utilization of ITASE Balance and Sea Level (ISMASS). Project facts records in comparisons with me- ITASE research reveals high vari- teorological reanalysis products. ability in surface mass balance and Project: ITASE Contact: Paul Mayewski, Connections are now noted be- the fact that single cores, stakes, [email protected] tween ITASE climate proxies and and snowpits do not represent the Participants: Scientifi c and logistics global scale climate indices such geographical and environmental institutions from 20 nations: , as ENSO, in addition to major characteristics of a local region. , Belgium, , , Chile, atmospheric circulation features Field observations show that the , , , India, , , over the Southern Hemisphere, interaction of surface wind and The Netherlands, New Zealand, , , South Korea, , UK, USA. such as the Amundsen Sea Low, subtle variations of surface slope Funding: National contributions East Antarctic High, and Antarctic have a considerable impact on Where: Antarctica Oscillation. Large-scale calibra- the spatial distribution of snow at When: Endorsed by the Scientifi c Committee tions between satellite-deduced short and long spatial scales. Data on Antarctic Research (SCAR). surface temperature and ITASE ice collected in the ITASE framework Activities since 1992 and ongoing. core proxies for temperature are and by associated projects (EPICA What: Snow pits, shallow and intermediate also now available. ITASE is also DC and DML, Siple Dome, Law ice cores covering decades to millennia, developing proxies for sea ice, a Dome, Dome Fuji) also reveals multiparameter analysis Web page: www.ume.maine.edu/itase/ critical component in the climate systematic biases compared to system. ITASE research is also fo- previous compilations.

PAGES NEWS, VOL.14, N°1, APRIL 2006 28 Science Highlights: Ice Core Science

Mayewski, P.A. and Goodwin, I., 1997: ITASE Science extended time-series become avail- past climate conditions with near- and Implementation Plan, Joint PAGES/GLOCANT able over broad regions through instrumental quality. Report. PAGESPAGES IPO, Bern - ITASE and deep drilling projects. Mayewski, P.A., Frezzotti, M., Bertler, N., van Ommen, The Antarctic-wide comparison of NOTE: T., Hamilton, G.H., Jacka, J., Welch, B., Frey, M., This article was abstracted from Mayewski Dahe, Q., Ren, J., Simoes, J., Fily, M., Oerter, H., glaciochemical records provides a Nishio, F., Iasaksson, E., Mulvaney, R., Holmund, P., et al., in press. This paper summarizes Lipenkov, V. and Goodwin, I., in press: The Interna- unique opportunity to achieve an ITASE accomplishments with references. tional Trans-Antarctic Scientifi c Expedition (ITASE) For details concerning national programs, understanding of the fundamental – An Overview, Annals of Glaciology. factors that ultimately control the the ITASE Science and Implementation Plan (Mayewski and Goodwin, 1997), and other chemistry of a snow or ice sample. ITASE information refer to the SCAR Project The ability to determine individual Office maintained at the Climate Change sources and pathways of aerosols, Institute, University of Maine (www.ume. as well as mechanisms that rule maine.edu/itase/). precipitation effi ciency and post- depositional effects, will allow the REFERENCES exceptionally detailed and accurate Bertler, N., Mayewski, P.A., Aristarain, A. and 46 others, in press: Snow chemistry across Antarc- interpretation of glaciochemical re- tica, Annals of Glaciology. cords necessary for reconstructing

A new 3000 m deep ice core drilled at Dome Fuji, Antarctica

YOSHIYUKI FUJII National Institute of Polar Research, Tokyo, Japan; [email protected] Introduction On 23 January 2006, the Japanese Antarctic Research Expedition (JARE) succeeded in drilling a 3029 m deep ice core at Dome Fuji in East Antarctica (77°19’01”S, 39°42’12”E, 3810 m asl; Fig. 1). Dome Fuji is the third place where a more than 3000 m deep ice core was collected in Antarctica, after Vostok (3623 m in Fig. 1: A bird’s eye view of the Antarctic ice sheet. Dome Fuji is located at the summit of Dronning Maud Land. This is the ideal place for ice core climate research because no horizontal depth, January 1998) and Dome C ice fl ow movements occur. (3270 m in depth, December 2004). The drilling will be continued next 2001/2002 season, and in Decem- chips from flowing out into the season in order to hit bedrock, ber 2003, drilling was resumed 40 borehole when the drill is being which is estimated to be located m away from the first borehole. winched up. The average drilling 3030±15 m below the surface. This time, we utilized a newly de- depth was 3.7 m/run and the speed A previous deep ice core, of veloped, highly effi cient drill, us- was 178 m/week until it got down 2503 m length, was drilled at Dome ing a pipe with small holes 2 mm to 3000 m depth. This is the fastest Fuji in December 1996, tracing back in diameter at intervals of 7 mm to performance ever in deep ice core to past 340 ka. The high resolution act as a chip chamber to store ice- drilling in the Antarctica and Green- stable isotope record (δ18O) showed cutting chips. We also developed land. Figure 2 shows a scene of the an extraordinary coherence (Wata- a bulb which prevents ice-cutting deep ice core drilling at Dome Fuji. nabe et al., 2003) with the deep ice Around 3000 m depth, the drill- core from Vostok (Petit et al., 1999), ing speed decreased sharply as which also reaches as far back in the drill hit “warm ice”. We took time but is located 1500 km away measures against this warm ice, from Dome Fuji. This fact strongly referring to the reports of deep ice supports a homogeneous climate coring at Dome C, NGRIP and oth- development over the last 340,000 ers. We changed the shape of the years on the high plateau of East drill cutter and the shape of the Antarctica. mount so that they would not easily get frozen and also coated the cut- Drilling of the new ice core ter with Tefl on. However, freezing of During the 1996 drilling, the drill “water” still made drilling diffi cult got stuck in the borehole and was and we could drill only about 0.5 m Fig. 2: Deep ice core drilling at Dome Fuji not able to be recovered. A new using a newly developed drill with highly effi - each run. drilling site was constructed in the cient performance.

PAGES NEWS, VOL.14, N°1, APRIL 2006