Award Abstract #0612506
Collaborative Research: A field validated model for melt-water infiltration and runoff from the Greenland Ice Sheet

NSF Org:	ARC Arctic Sciences Division
Initial Amendment Date:	August 25, 2006
Latest Amendment Date:	August 25, 2006
Award Number:	0612506
Award Instrument:	Standard Grant
Program Manager:	William J. Wiseman, Jr. ARC Arctic Sciences Division OPP Office of Polar Programs
Start Date:	September 1, 2006
Expires:	August 31, 2009 (Estimated)
Awarded Amount to Date:	$159475
Investigator(s):	Joel Harper joel@mso.umt.edu (Principal Investigator)
Sponsor:	University of Montana 32 CAMPUS DRIVE MAIN HALL MISSOULA, MT 59812 406/243-6671
NSF Program(s):	ARCTIC NATURAL SCIENCES, ARCTIC RESRCH SUPPRT & LOGISTI
Field Application(s):	0311000 Polar Programs-Related
Program Reference Code(s):	OTHR, 9150, 1079, 0000
Program Element Code(s):	5280, 5205

ABSTRACT

ABSTRACT

Harper

OPP-0612506

Pffeffer

OPP-0612351

Humphrey

OPP-0612374

Satellite observations suggest substantial year-to-year increases in surface melt extent of the Greenland Ice Sheet (GIS). Both the area and duration of snow melting in the percolation facies, a wide band of intermediate elevation that circumscribes the ice sheet, are increasing. The fate of the melt water, however, is unclear as in-situ observations in Greenland's percolation facies have been extremely limited. The ultimate hydrologic result of these changes is a significant change in meltwater production and runoff from GIS, however, the coupling between snow processes and runoff are poorly documented. In particular, the runoff limit, the altitude above which seasonal melt infiltrates, refreezes, and does not escape, lies within the higher part of the percolation facies, but its precise location is generally unknown, and the response of the runoff limit to warming is poorly understood. Current models for present and future contributions of GIS to sea level rise use a model which established rough bounds on the response of the "runoff limit" to secular increases in melt. This research will quantify melt water runoff processes and changes in near-surface firn densification in the percolation facies of GIS and will produce a new and highly improved model for runoff that is anchored in experimental observations. Experiments will be conducted at sites along a transect in the region of Crawford Point, extending from about 2025 m to 1500 m elevation. Specific objectives are twofold: 1) the Principal Investigators will determine km-scale melt water flow velocities and pathways which will serve as calibration for their runoff model; and 2). they will investigate change in near-surface densification rates and processes in records that span over 25 years. This work will increase our understanding and prediction capabilities of the fraction of meltwater which runs off the ice sheet, document change in important physical processes occurring on the ice sheet, and provide rare ground observations for comparison to satellite based measurements of surface melt. Each of these has important implications for interpretation of the ice sheet's surface elevation, mass balance, and flow dynamics and ultimately, global eustatic sea level.

Broader Impacts: The Principal Investigators are active teaching faculty engaged in undergraduate and graduate teaching, and graduate student mentoring. They will collectively teach over 90 credit hours of undergraduate and graduate courses. This research and related scientific issues will add pedagogical benefit to numerous courses. This project will lead to at least four graduate degrees. They regularly conduct outreach activities with k-12, the general public, and the oil and gas industry.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Brown, J. M.;Bradford, J. H.;Harper, J. T.;Pfeffer, W. T.;Humphrey, N. F.;.  "Ice Penetrating Radar Surveys Along The EGIG Line In The Percolation Aone of Western Greenland,"  Eos Trans. AGU,  v.88(52),,  2007,  p. Abstract.

Harper, J. T.;Humphrey, N. F.;Pfeffer, W. T.;Brown, J. M.;Schuler, D. R.;Sturgis, D.;.  "Field Measurement of Past and Present Meltwater Infiltration in the Percolation Zone of the Greenland Ice Sheet,"  Eos Trans. AGU,  v.88(52),,  2008,  p. Abstract.

Harper, J. T.;Humphrey, N. F.;Pfeffer, W. T.;Brown, J.;Schuler, D. R.;Sturgis, D.;.  "Densification and Melt water Runoff on The Greenland Ice Sheet,"  Workshop on the Mass Balance and Dynamics of Arctic Glaciers,  v.Extende,  2008,  p. 60-61.

Pfeffer, W. T.;Harper, J. T.;O.  "Kinematic Constraints on Outlet Glacier Response and Land Ice Contributions to 21st Century Sea Level Rise,"  Science,  v.(accept,  2008, 

Pfeffer, W. T.;Rick, U. K.;Engel, C.;Harper, J. T.;Anderson, R. S.;Meier, M. F.;Anderson, S. P.;.  "Kinematic Constraints on Greenland Contribution to Sea Level Rise in the Next Century,"  Eos Trans. AGU,  v.88(52),,  2007,  p. Abstract.


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