Journal of Geophysical Research: Earth Surface

Cover image for Vol. 122 Issue 4

Impact Factor: 3.318

ISI Journal Citation Reports © Ranking: 2015: 27/184 (Geosciences Multidisciplinary)

Online ISSN: 2169-9011

Associated Title(s): Journal of Geophysical Research

Tracking meltwater retention in Greenland

In Greenland, surface melt has increased significantly in area and intensity in recent years. Melting has increased in the accumulation area, normally a region of snow accumulation. This increase in meltwater can affect the ice sheet's mass balance and ice flow dynamics. When melt occurs on the surface, meltwater may trickle down through snow a short distance vertically and then refreeze, forming thin ice layers, or it may penetrate underlying snow and create pools, or it may migrate horizontally and become runoff. The fate of meltwater is not well understood because the processes of meltwater infiltration into an ice sheet have not been well measured. Humphrey et al. (2012) measured the thermal signature of meltwater infiltration and retention at 14 sites in Greenland from 2007 to 2009. The measurements covered the entire annual melting and refreeze cycles. They documented three different mechanisms of meltwater motion and freezing. They found that vertically infiltrating meltwater penetrates as much as 10 m deep through cold, compact snow that has accumulated over decades and even through ice layers. In addition, the researchers observed that meltwater retention depended on elevation. During their study period, runoff occurred at elevations lower than about 1500 m, but meltwater was completely retained in the ice sheet at higher elevations.

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