Snow & Firn Microstructure Biogeochemical Cycling Radar Profiling Internal Stratigraphy Mass Balance Satellite Image Analysis Stable Isotopes Trifluoroacetate Accomplishments and Contributions ITASE US ITASE West Antarctic Ice Sheet Initiative Global Change and the Antarctic Scientific Committee on Antarctic Research International Geosphere-Biosphere Programme

Accomplishments and Contributions

Contributions - Accomplishments - Publications

US ITASE Scientific Contributions

US ITASE science activities in West Antarctica (1999-2003) comprise 11 currently funded research programs (Table 1).

Table 1. Currently funded US ITASE research programs in West Antarctica (* denotes expressed interest in 2003-2005 activities).

To date, 63 scientific products (abstracts, papers, reports that are published, in press, or at advanced stages of preparation) have been produced by research teams involved in US ITASE (for detailed citations please refer to the US ITASE web site). In the process, US ITASE has made several major scientific contributions (examples of citations from the literature included):

1. Field studies to understand features in RADARSAT and other satellite imagery (Shuman and Comiso, 2001; Guo et al., 2003; Hamilton, 2001; Hamilton and Spikes, 2002; Stearns et al., in preparation, Schneider and Steig, in review; Schneider et al., in preparation);
2. Identification of surface and deep radar reflectors as continuous time-stratigraphic horizons across the thousands of km of traverse route (Arcone, 2002a, b; Arcone et al., 2001a, b, c; Spikes et al., 2001, 2002; Hamilton et al., 2000);
3. Ice core calibration of radar reflectors in the upper 100 meters of the ice sheet to determine the source of these reflectors (Arcone, 2002a; Arcone et al., 2001a, b, 2002);
4. Examination of spatial variability in major ions over West Antarctica and relationship to sources (Kreutz and Mayewski, 1999; Kreutz et al., 1999, 2000; Dixon et al., 2001; Isaksson et al., 2001; Kaspari et al., 2002);
5. Ice core reconstructions of seasonal, interannual and decadal scale variability in accumulation rate, temperature, atmospheric circulation, volcanic activity, and sea ice extent and relation to models (Kreutz and Mayewski, 1999; Reusch et al., 1999; Hamilton et al., 2000; Qin et al., 2000; Guo et al., in review; Guo et al., 2002; Meese and Gow, 2002; Meyerson et al., in review; Isaksson et al., 2001; Souney et al., in review; Palmer et al., 2001; Steig, et al., in preparation; Bertler et al., in review; Dixon et al., 2002);
6. Identification of ENSO, ACW (Antarctic Circumpolar Wave), PDO (Pacific Decadal Oscillation), EAH (East Antarctic High), and ASL (Amundsen Sea Low) atmospheric circulation structure in glaciochemical time-series, and implications and relationship to models (Kreutz et al., 2000; Mayewski and White, 2002; Meyerson et al., 2002, in review; Bromwich et al., 1999, 2003; Mayewski et al., 2001, Steig et al., 2001, 2002, in preparation; Souney et al., in review; Goodwin et al., in review);
7. Assessment of modern global climate change (short-term variability in snowfall, temperature, and atmospheric circulation, pollution) in the context of decadal to centennial-scale variability (Reusch et al., 1999; Qin et al., 1999; Hamilton et al., 2000; SCAR ISMASS Committee (including GSH), in preparation; Meese and Gow, 2002);
8. Deconvolution of local-scale variability in ice core-derived accumulation rate compared to regional scale variability (Hamilton et al., 2000, Arcone et al., 2002);
9. Glaciological reconnaissance for potential deep drilling sites (Hamilton et al., in preparation; Frey et al., 2002);
10. High resolution mapping of subglacial topography in previously unexplored regions (Welch and Jacobel, 2001, 2002);
11. Characterization of ice flow dynamics based on deformation of internal stratigraphy, basal and ice surface topography (Welch and Jacobel, 2001, 2002);
12. Characterization of basal reflectivity based on changes in basal temperature and/or geology (Welch and Jacobel, 2001, 2002);
13. Air sampling in the interior of West Antarctica and air-snow processes (Frey et al., 2001, 2002, Albert, in preparation; Albert and Leeman, 2002);
14. Snow and firn permeability and microstructure measurements at locations with greatly differing accumulation rates and average temperature (Albert, 2001, 2002; Albert and Leeman, 2002, in preparation);
15. Physical property measurements of annual layer stratigraphy, depth/density profiles and crystal growth profiles as a function of age and in situ temperature in snow pits and ice cores (Gow and Meese, 2002).

US ITASE Technical and Logistical Accomplishments

US ITASE has accomplished the following technical and logistical activities during the 1999-2002 field period; included in parentheses is the expected total following the 2002-2003 field season.

1. The traverse traveled a total of ~4,000 km (5,500 km) sampling a significant portion of West Antarctica (Figure 1).
2. Continuous radar observations (crevasse detection (400 MHz) and shallow depth (200 MHz)) over the ~4,000 km (5,500 km) of the traverse route and deep radar (2.5 MHz) over ~2,000 km (~3,500 km).
3. Occupation of fifteen (20) science sites for periods of 2-6 days depending upon workload per site.
4. A total of ~1,500 m (~2,100 m) of ice core recovered utilizing both the 3” diameter Eclipse drill purchased by NSF for use by US ITASE and a 2.2” diameter lightweight drill built by Glacier Data for the University of Maine. A total of 16 (20) 3” diameter ice cores collected from 15 (20) sites covering a minimum of 200 years (typically >500-1000 years). Ice cores sampled at NICL for chemistry, stable isotopes, density and total ? activity.
5. Permeability and porosity experiments conducted at 7 (10) snow pits and using 6 (9) 18 m ice cores returned to CRREL.
6. Stratigraphy sampled at all sites utilizing snow pits excavated either exclusively for this purpose, or snow pits excavated as access for 3” ice coring, or ~10 m wide pits excavated using a Challenger 55 tractor blade.
7. Forty-two (60) days of atmospheric and shallow chemistry observations conducted at 10 (15) sites. Sampling includes real-time, continuous observations of peroxides (H2O2 and organic peroxides), formaldehyde, and near-surface ozone profiles and ozone profiles up to an altitude of 23 km.
8. Basic meteorological observations collected at all sites and 10 m depth temperatures for comparison with infrared satellite estimates of mean annual temperature.
9. Continuous geodetic-quality GPS profiles along the ~4,000 km (5,500 km) of the traverse route, and continuous base station data collection for ~50 days each season.
10. Thirteen (18) high precision GPS ‘coffee can’ experiments deployed to calculate mass balance and measure flow velocities.
11. Three AWS deployed close to the proposed inland deep drilling WAIS site.

US ITASE Publications

Hamilton, G., Arcone, S.A., Yankielun, N.E., and Mayewski, P.A., 2000. Spatial variation in snow accumulation rates investigated using ground penetrating radar and GPS. AGU Fall Meeting, San Francisco, 2000.

Spikes, V. B., Arcone, S. A., Hamilton, G., and Mayewski, P.A. 2001. Examining the causes of reflecting horizons in high-resolution radar profiling of polar firn. AGU Spring Meeting, Boston, 2001.

Arcone, S. A., Mayewski, P. A., and Hamilton, G. 2001. Continuity and Reflectivity of Radar Horizons in the West Antarctic Firn Stratigraphy along the ITASE Traverse. AGU Spring Meeting, Boston, 2001.

Arcone, S. A., Hamilton, G., and Mayewski, P.A. 2001. Stratigraphic profiling of the West Antarctica firn regime with 400-MHz GPR, Ext. Abstr. Proc., SEG 71st Annual Meeting, San Antonio.

Arcone, S. A. 2002. Stratigraphic profiling of antarctic firn with 400-MHz gpr at 1500 ns. Proc. Ninth Internat. Conf. On Ground Penetrating-Radar, Santa Barabara, Ca, April.

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