This project uses funds, under the auspices of the Rapid Response Research (RAPID) concept grants, to investigate the single most extensive loss of ice from a Greenland glacier known to date that occurred between August 3 through 5, 2010.
Specifically, the investigator will use the funds to retrieve data sensors and other equipment, such as time lapse cameras and GPS units, that were in place at the time of the ice loss and that are now adrift on an ice island that has become detached from the Petermann Glacier. If the ice island fractures into smaller pieces, it will become more difficult to find the site and the sensors could be lost forever in the sea.
The intellectual merits of the proposed work include: 1) increasing the understanding of the dynamics associated with ice shelf disintegration including deriving a precise quantitative assessment of the flow speed changes of up-stream glacier ice post-detachment; 2) time-lapse camera and GPS data will yield quantitative measurements of the effects of ocean tides on ice velocity; and 3) ice flexure measured by the GPS will inform ice shelf rheology studies.
The broader impacts include: 1) capturing details of the 275 km2 Petermann Glacier breakup occurring between 3 and 5 August, 2010. The details added by this in-situ data recovery will add much onto what is being learned from the satellite perspective; and 2) the ability to share with the world the imagery of the actual breakup event from the time-lapse cameras.
The proposed activities fit well into the potentially transformative, high risk, and quick-response research on natural or anthropogenic disasters nature of the RAPID program.
With joint support from the US National Science Foundation and the UK NERC, during late July, 2011, a helicopter charter enabled data and equipment recovery from GPS, time-lapse cameras, and meteorological stations installed in far northwest Greenland. The sensors were set in anticipation of a large ice area detachment that occurred by 5 August, 2010. In-person reaction Alun Hubbard: "Although I knew what to expect in terms of ice loss from satellite imagery, I was still completely unprepared for the gob-smacking scale of the breakup, which rendered me speechless." ... "What the breakup means in terms of inland ice acceleration and draw-down of the ice sheet remains to be seen, but will be revealed by the GPS data recovered, which we are now processing at Aberystwyth." Before-After photos The 2011 site visit enabled taking photos to pair with photos taken during the 2009 field campaign. To the right of this web page are 3 image pairs (6 photos) edited by Jason that document the enormous ice area changes in Petermann fjord. Animations Jason combined the photo pairs into animations that either fade from one image to the other or flicker back and forth. Click below. You will get a more fluid animation after the first loading because the file sizes are large (>50 Mb)... 1. view looking up fjord; fade or flicker. 2. view from NW; fade or flicker. 3. view from NE; fade Scientific Findings The GPS document an ice flow regime that is surprisingly sensitive (~15% velocity change) to ocean tidal variation. There was also a flow regime change associated with the 'ice island' detachment. Articulating that subtle change is part of a manuscript in preparation for publication. The after photos indicate sediment rich water in the part of the fjord now ice-free. It was not obvious prior to this 13 km retreat that there was so much water communicating with the glacier bed, entraining the sediment. Thus, melt water is intera Scientific Assessment The August 2010 ice calving at Petermann is the largest in the observational record for Greenland Falkner et al. (2011) scoured the observations and found no evidence of an event this large in scattered observations since 1876. Johannessen et al. (2011) identified the next largest observed Petermann calving event ocurring in 1991, being 58% as large as the 2010 event. In an December 2010 AGU presentation, J. Box concluded that of 38 glacier surveyed, it was only at the 6 glaciers with ice shelves* that a significant statistical link between land and sea surface temperatures and area change was evident. The physical reasoning why ice shelves respond to land and sea surface temperature change is that ice shelves are constrained to near sea-level, where temperature variations are most influential to surface melting. The surface slope of ice shelves is ~0. Glaciers climb within a few km (steeply) into colder parts of the atmosphere where surface melt rates decrease quickly. Water ponding on the surface, being much darker than a bare ice surface, concentrates solar energy, enhancing melt rates. A water filled depression, acting under gravity, has unlimited capacity to hydraulically jack through cracks in the glacier, provided it is kept filled with water. During the 24 h Arctic summer, the condition of unlimited water supply can be maintained on a glacier for weeks on end. Other factors such as tidal flexure and wind stress can be the straw that breaks the glaciers back. (*) ice shelves: Petermann; Zachariae; Nioghalvfjerdsbrae/79; Ostenfeld; Jakobshavn; and Ryder Works Cited - Falkner K.K., A.M. Münchow, J.E. Box, T. Wohlleben, H.L. Johnson, P. Gudmandsen, R. Samelson1, L. Copland, K. Steffen, E. Rignot and A. K. Higgins, (2011), Context for the Recent Massive Petermann Glacier Calving Event, Eos Trans. AGU, 92(14), doi:10.1029/2011EO140001. - Johannessen, O. M., Babiker, M., and Miles, M. W.: Petermann Glacier, North Greenland: massive calving in 2010 and the past half century, The Cryosphere Discuss., 5, 169-181, doi:10.5194/tcd-5-169-2011, 2011. Broader Impacts The funded activity has advanced knowledge in glaciology, climatology, and oceanography, especially at the intersection of these disciplines. See section entitled Scientific Findings, above. The individual and team of field investigators are well-experienced for this work, from numerous past research experiences in Greenland and on its inland ice and glaciers. The work explores creative and original use of GPS and time-lapse photography to quantify marine-terminating glacier interactions with ocean (tides) and climate (surface melting and winds)
