ABSTRACT

ABSTRACT
Bevis
OPP-0632320
Csatho
OPP-0632310

Intellectual Focus. This is a collaborative proposal from Principal Investigators at Ohio State University and SUNY Buffalo. They will construct a network (GNET) of continuous GPS stations in Greenland as part the U.S. contribution to the International Polar Year (IPY) and the international POLENET consortium. They will use this network to map the steady vertical velocity field associated with postglacial rebound (PGR), which will provide GRACE, and any successor missions, with an accurate 'PGR correction', thereby suppressing by far the largest source of uncertainty in GRACE-based estimates of ice mass changes in Greenland. They intend to use GNET to 'weigh' annual and interannual changes in ice mass, obtaining better spatial resolution than GRACE is capable of, using Earth's instantaneous elastic response to surface load changes. This approach will be calibrated and validated by relating annual or seasonal patterns of loading (the cause) with in-phase seasonal oscillations of adjacent bedrock. Having calibrated a 'weighing machine' in this way, the Principal Investigators will be able to quickly detect and analyze any abrupt increases in long terms rates of ice gain or loss.

Relevance to IPY: POLENET (Polar Earth Observing Network) is a consortium involving 24 nations that will dramatically improve the coverage in geodetic, magnetic, and seismic data across the polar regions during IPY. GNET, which involves three international partners, constitutes the largest component of a POLENET deployment across Greenland, and is the only POLENET component in the northern hemisphere which is focused on a major ice sheet. It will complement GPS initiatives elsewhere in the Arctic to be carried out by more than 12 nations participating in POLENET. POLENET will overcome the scarcity of observational systems in the Earth's polar regions, and will provide a legacy in observational infrastructure and in the technological capability to deploy autonomous operations in extreme environments. The GPS data and metadata will be made available to the global science community as soon as they reach the UNAVCO archive.

Broader Impacts. The POLENET project will bring about the development of new technologies for operating autonomous stations in the Arctic and Antarctic. It will promote one of the most holistic collaborations between glaciologists, geodesists, geophysicists, geologists, meteorologists and oceanographers in the history of these disciplines. This project will leverage NASA's GRACE project to an entirely new level of importance, because providing GRACE with a "PGR correction" will transform it into the single most powerful measurement system ever developed for the direct observation of mass transfer between the ice sheets and the oceans. GNET will be able to detect any rapid acceleration in ice mass gain or loss in Greenland, especially at the critical margins of the ice sheet, in response to changing climatic conditions. Even more broadly, understanding and monitoring the behavior of the Greenland (as well as the Antarctic) ice sheet,
is a matter of tremendous societal importance. It is widely understood that there is serious danger that the West Antarctic or Greenland ice sheets could collapse and so seriously damage the global economy, and degrade the social infrastructure supporting hundreds of millions of people, by inundating large swaths of densely inhabited coastal areas worldwide. While it may be too late to reverse global warming before sea level rise becomes seriously problematic, it is crucial to assess both the possible severity of sea level rise, and the amount of time that our governments have to respond to, or mitigate, developments that they may be powerless to prevent. Given the importance of this agenda, we propose to develop an outreach component using UNAVCO's outreach specialists.

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