Greenland Ice Sheet flow response to runoff variability

• Published in: Geophysical Research Letters
• Main Authors: Stevens, Laura A., Behn, Mark D., Das, Sarah B., Joughin, Ian, Noël, Brice, van den Broeke, Michiel R., Herring, Thomas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Ltd 2016
• Subjects: Greenland Ice Sheet; ice flow; runoff; Dynamical response; Global positioning system networks; Ice sheet models; Interannual variability; Negative correlation; Relevant feedback; Geophysics; Earth and Planetary Sciences (all); General Earth and Planetary Sciences; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Greenland; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/301898; https://orbi.uliege.be/bitstream/2268/301898/1/Stevens_GRL_2016.pdf; https://doi.org/10.1002/2016GL070414

peer reviewed 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.