Expressions of Intent for International Polar Year 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

Ice Discharge from the Greenland Ice Sheet Using Airborne Interferometric SAR  (Greenland Discharge)

Outline
Recent studies have demonstrated that the Greenland Ice Sheet contributes about 0.13 mm/yr to global sea level rise [Krabill, et al., 2000]. Greenland loses mass in roughly equal proportions through surface melting and outlet glacier discharge. Ice sheet models predict that Greenland will undergo significant shrinkage through enhanced melt under many greenhouse warming scenarios [Gregory, et al., 2004]. These models, however, do not incorporate outlet glacier dynamics that can lead to enhanced discharge and dynamic thinning. In fact, observations suggest that much of the current loss is the result of strong thinning (> 1 m/yr) near the grounding lines of many of Greenland’s outlet glaciers [Abdalati, et al., 2001]. In particular, Jakobshavn Isbræ, Greenland’s largest outlet glacier, recently doubled its speed to more than 12 km/yr [Joughin, et al., 2004], increasing its discharge rate by roughly 25 km3/yr and thinning by several meters per year [Thomas et al., 2003]. These changes are significant and may indicate a response to climate change (e.g., enhanced basal lubrication from surface melt draining to the bed or dynamic response to the loss of floating ice tongues in a warmer ocean). With the advent of interferometric synthetic aperture radar (InSAR) and radio echo sounding (RES) the technical means for estimating ice discharge have been well established [Rignot, et al., 1997; Joughin, et al., 1999]. Despite this progress, discharge has not been measured for many outlet glaciers. Many of Greenland’s outlet glaciers flow at rapid rates through narrow outlets in areas of high accumulation. The resulting high shear and weathering make InSAR with the current generation of spaceborne SARs difficult for many outlet glaciers. NASA has funded the development of an airborne repeat-pass interferometric SAR scheduled for completion in 2007. The high resolution and selectable repeat interval of this instrument make it the ideal tool for measuring outlet glacier discharge in Greenland. Advanced radars for ice thickness measurements and internal layers mapping [Gogineni, et al., 2001] are being developed as a part of NSF-NASA funded project. These radars will be used to collect additional data on ice thickness, accumulation rate and basal conditions in support of the proposed IPY project.Using the combination of ice thickness and velocity data from the UAV flights, ice discharge can be measured for the vast majority of Greenland’s outlet glaciers. The scale of the Greenland ice sheet is such that these measurements could be obtained over a period of a few weeks. Such a campaign will provide a comprehensive and simultaneous baseline measurement of discharge through all of Greenland’s will be a major contribution to IPY.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
By providing a baseline measurement of ice discharge the project will make a major contribution to Theme 1: the current state of the polar environment. These data can be compared to the regions in Greenland where there are existing discharge data to address Theme 2: change in polar region. In addition, this project will provide important baseline measurements necessary for detecting future change.

What international collaboration is involved in this project?
We have had preliminary discussions with Neils Reeh of Denmark who is interested in participating in the project. We also plan to collaborate with other glaciologists in Denmark. Søren Madsen, manager of the Radar Science and Engineering Section, where the UAV SAR is being built at JPL is also the former director of the Danish Center for Remote Sensing. Thus, we anticipate potential collaboration with Danish radar scientists on technical issues related to the radar.

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
Entire margin of the Greenland Ice Sheet.

Approximate timeframe(s) for proposed field activities:
Arctic: Several campaigns from 04/07 through 09/08            
Antarctic: n/a

Significant facilities will be required for this project:
Fuel for the aircraft and use of existing landing strips.

Will the project leave a legacy of infrastructure?
The data will be the main legacy of the project. The UAV SAR is being developed independently of IPY. It should be available for future campaigns beyond IPY.

How is it envisaged that the required logistic support will be secured?

Has the project been "endorsed" at a national or international level?
Submitted to US IPY committee.See also attached note on General project endorsement by the Danish National Committee for IPY.

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?


The UAV SAR is being developed independently of the IPY. The campaigns to map Greenland outlet glacier velocity and discharge are directly related to IPY and will be one of the first deployments of the instrument.

How will the project be organised and managed?
The program will be managed by a collaborative group of NASA PI’s and an international group of university PI’s. We will also explore partnership with NSF for additional funding.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
Existing funding agencies already require a strong education and outreach programs as well as a strong emphasis on demonstrating societal benefit. These outreach efforts will be coordinated to highlight their role in the IPY.

What are the initial plans of the project to address data management issues (as outlined in the Framework document?
NASA proposals have strict data archiving and management requirements. We will work with the NSIDC (Natl. Snow/Ice Data Center) for long-term archiving and distribution of the data products.

How is it proposed to fund the project?
We will pursue additional funding from NASA to support the deployment of the instrument to Greenland.

Is there additional information you wish to provide?
None

PROPOSER DETAILS

Dr. Ian Joughin
Applied Physics Lab, University of Washington
1013 NE 40th Street
Seattle, WA
98105-6698
USA

Tel: 206-221-3177
Mobile: no
Fax: 206-616-3142
Email:

Other project members and their affiliation