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| Project Title | Quantifying recent mass changes of mountain glaciers in the Canadian High Arctic, the Patagonian Icefields, and eastern Greenland: an integrated approach using GRACE, airborne and field observations |
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| Funding Agency | NASA Research Opportunities in Earth and Space Sciences, Cryospheric Sciences (Grant number NNH07ZDA001N-CRYO) |
| Principal Investigator | Anthony Arendt |
| co-Investigators | Waleed Abdalati, Scott Luthcke, David Rowlands, William Krabill |
| Collaborators | David Burgess, John Sonntag |
| Duration | 2008-2011 |
Project Summary
According to the fourth assessment of the Intergovernmental Panel on Climate Change, mass losses from mountain glaciers and ice caps during 1993-2003 were greater than the combined mass losses during the same time period from the Greenland and Antarctic ice sheets. This is remarkable because mountain glaciers and ice caps (hereafter mountain glaciers) make up only 4% of Earth's land ice cover. Despite their importance in the global water cycle, mountain glaciers are under-sampled, and existing estimates of their contribution to rising sea level have large errors. In order to reduce these errors and close the gap between observed and estimated contributions to rising sea level, we require a monitoring strategy that is global in coverage and allows for large-scale sampling of glacier systems using a consistent methodology. This project will provide the most comprehensive assessment of the present (2003-2007) contribution of mountain glaciers to rising sea level, by combining data from the Gravity Recovery and Climate Experiment (GRACE), the NASA Airborne Topographic Mapping (ATM) program, and available in situ data. Because of its global coverage and ability to measure temporal changes in Earth mass, GRACE data will form the backbone of our assessments. Our approach will be to fine-tune high-resolution GRACE mascon solutions developed by the NASA Goddard Space Geodesy group to determine regional variations in glacier mass balance. The mascon solution procedure provides exceptionally high temporal (10 day) and spatial (2 by 2 degree) resolution of gravity variations, but in order to isolate glacier mass variations, a unique set of procedures is required. We are developing these procedures in a currently-funded study in which we have determined the precise layout of the GRACE solution domain, the application of appropriate spatial and temporal solution constraints, and the modeling of non-glacier sources of mass variation. We have tested these procedures on glaciers in Alaska and northwestern Canada, yielding mass changes that compare very well with previous airborne measurements. Our goal in this study is to combine GRACE, ATM and in situ data for other regions on Earth containing large concentrations of mountain glaciers, including the glaciers of the Canadian high Arctic, the Patagonian Icefields of South America, and mountain glaciers peripheral to the Greenland ice sheet. We will begin by validating GRACE estimates of glacier mass variability against in situ and ATM data where available. After using these comparisons to develop and refine our GRACE solution procedure, we will apply it to mountain glaciers of eastern Greenland and Patagonia where there is insufficient ATM data for validation work. Our study will reduce errors in the global budget of mountain glacier mass balance, help close the gap between observed and estimated global contributions to rising sea level, and inform future satellite, aircraft and in situ measurement campaigns.