Greenland Ice Sheet; ice flow; runoff; Dynamical response; Global positioning system networks; Ice flow; Ice sheet models; Interannual variability; Negative correlation; Relevant feedback; Geophysics; Earth and Planetary Sciences (all); General Earth and Planetary Sciences
Abstract :
[en] We use observations of ice sheet surface motion from a Global Positioning System network operating from 2006 to 2014 around North Lake in west Greenland to investigate the dynamical response of the Greenland Ice Sheet's ablation area to interannual variability in surface melting. We find no statistically significant relationship between runoff season characteristics and ice flow velocities within a given year or season. Over the 7 year time series, annual velocities at North Lake decrease at an average rate of −0.9 ± 1.1 m yr−2, consistent with the negative trend in annual velocities observed in neighboring regions over recent decades. We find that net runoff integrated over several preceding years has a negative correlation with annual velocities, similar to findings from the two other available decadal records of ice velocity in western Greenland. However, we argue that this correlation is not necessarily evidence for a direct hydrologic mechanism acting on the timescale of multiple years but could be a statistical construct. Finally, we stress that neither the decadal slowdown trend nor the negative correlation between velocity and integrated runoff is predicted by current ice-sheet models, underscoring that these models do not yet capture all the relevant feedbacks between runoff and ice dynamics needed to predict long-term trends in ice sheet flow.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Stevens, Laura A. ; Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering, Woods Hole, United States
Behn, Mark D. ; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, United States
Das, Sarah B. ; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, United States
Joughin, Ian ; Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, United States
Noël, Brice ; Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie ; Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands
van den Broeke, Michiel R. ; Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands
Herring, Thomas ; Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, United States
Language :
English
Title :
Greenland Ice Sheet flow response to runoff variability
NSF - National Science Foundation [US-VA] [US-VA] NASA - National Aeronautics and Space Administration [US-DC] [US-DC] [US-VA]
Funding text :
National Science Foundation's Office of Polar Programs; National Aeronautics and Space Administration's (NASA) Cryospheric Sciences Program; National Science Foundation Graduate Research Fellowship; American Geophysical Union Horton Research Grant
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