Expressions of Intent for International Polar Year 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Exploring the Spatial Distribution of Water Beneath the Greenland Ice Sheet Over the North-GRIP Area Using Radar  (Radar-Mapping of NGRIP Basal Water)

Outline
The overarching goal of this proposal is to begin detailed exploration of the spatial distribution of liquid water at the base of the Greenland ice sheet. Recent discoveries of basal ablation at the site of the NGRIP (Grinsted and Dahl-Jensen, 2002) and in northeast Greenland (Fahnestock et al., 2001) upend earlier assumptions that the modern ice sheet is (nearly) everywhere frozen to its bed. The unknown distribution of wet-bed conditions has potentially major implications for modeling ice dynamics, and thus for estimates of ice sheet extent, divide locations, and contributions to sea level since the Eemian (Marshall and Cuffey, 2000; Cuffey and Marshall, 2000). Moreover, the spatial distribution of bed wetness bears strongly on the investigation of Proterozoic crustal blocks of differing thickness, whose boundary may run between the Greenland Summit and the NGRIP site (Dahl-Jensen et al., 2003). Searching for and mapping any spatial structure in the distribution of basal wetness is therefore a task of high priority. The opportunity to begin this task now exists, based on the combination of a new observational method with an extensive, existing radar survey. Specifically, because the true radar reflectivity of wet material significantly exceeds that of dry (frozen) material, calibrated radar surveys offer a way to probe spatial variations in basal wetness by observing variations in apparent basal reflectivity. The Alfred-Wegener-Institut has surveyed an extraordinarily finely spaced grid, approximately 200 km on a side and centered on the NGRIP site, with a calibrated, 150 MHz, airborne radar (Nixdorf and Göktas, 2001). This survey is an exceptional resource, but taken by itself is limited by the fact that many variations in the ice sheet can cause the calibrated bed echo (i.e., the apparent bed reflectivity) to vary independently of the true reflectivity – and it is only the latter that reliably indicates wetness. The ice sheet variation most problematic to estimate from ancillary data is englacial radar absorption. Winebrenner et al. (2003) have, however, recently developed a method for the direct measurement of englacial absorption using bistatic, ground-based radar method. We propose to measure englacial absorption at a number of judiciously chosen points in the NGRIP area in a modest field program during a single season. We will combine out new knowledge of englacial absorption with the existing AWI survey to map true basal reflectivity and basal wetness. Any spatial structure in the wetness map will be evaluated in light of other available geophysical data.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
The result will be our first look at the spatial distribution of wet-bed boundary conditions beneath the present-day ice sheet, as well as insight into the spatial distribution of geothermal heat fluxes in the context of other new geological knowledge.

What international collaboration is involved in this project?
The project is a collaboration between 2 universities in the US and the Alfred-Wegener-Institut in Bremerhaven, Germany.

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
North Central Greenland.

Approximate timeframe(s) for proposed field activities:
Arctic: spring/summer 2006 or 2007            
Antarctic: n/a

Significant facilities will be required for this project:
Fixed wing transport aircraft , radars, snowmobiles

Will the project leave a legacy of infrastructure?
The methods for estimating englacial attenuation will be freely promulgated to all interested radar groups.

How is it envisaged that the required logistic support will be secured?
Own national polar operator
Another national polar operator
National agency
Military support
Commercial operator

Has the project been "endorsed" at a national or international level?
Not yet -- the project is being proposed to the US NSF Arctic Natural Sciences program.

PROJECT MANAGEMENT AND STRUCTURE

Is the project a short-term expansion (over the IPY 2007-2008 timeframe) of an existing plan, programme or initiative or is it a new autonomous proposal?
New

How will the project be organised and managed?
Project management will reside at the University of Washington, with the PI (Winebrenner) in close consultation with the field team leader (Matsuoka) and all co-investigators.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
In addition to supporting the work of a graduate student toward a doctoral dissertation, this project will recruit two science- and outdoor-oriented undergraduate students for the field team, thus providing first-hand research experience. To reach a larger and younger set of students, the project will undertake K-12 teacher training in several aspects of the project (both electromagnetic and geophysical), by means of teacher workshops presented in collaboration with the UW NASA Space Grant program.

What are the initial plans of the project to address data management issues (as outlined in the Framework document?
We expect to archive data and results at the US National Snow and Ice Data Center.

How is it proposed to fund the project?
The project is being proposed for US NSF support.

Is there additional information you wish to provide?

PROPOSER DETAILS

Pro Dale P. Winebrenner
Applied Physics Laboratory, Box 355640
University of Washington
Seattle, Washington
98195
USA

Tel: 206-543-1393
Mobile: no
Fax: 206-616-3142
Email:

Other project members and their affiliation