Tidal Modulation of Ice Flow on Helheim Glacier, East Greenland

• Main Authors: Betty Churchill, Exploration Fund, Leigh A. Stearns
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland; Meier; Stearns; East Greenland; glacier; Ice Sheet; Tidewater
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.558.9249; http://climatechange.umaine.edu/Research/projects/students/2007reports/Stearns07ChurchillReport.pdf

Mass from the interior of the Greenland Ice Sheet is transported to the ocean by numerous large, fast-flowing outlet glaciers. Changes in the flow configuration of these outlet glaciers modulate ice sheet mass balance and sea level. Recent estimates show that Greenland’s contribution to sea level more than doubled in the past decade, increasing from 0.23 ± 0.08 mm/yr in 1996, to 0.57 ± 0.10 mm/yr in 2005, and that the majority of this mass loss is due to changes in the dynamics of a few large outlet glaciers [Rignot and Kanagaratnam, 2006; Stearns and Hamilton, 2007]. One of these glaciers is Helheim Glacier (Figure 1), a tidewater glacier in southeast Greenland. Ocean tides are known to affect the flow of glaciers terminating at tidewater [e.g. Lingle et al., 1981, Meier and Post, 1987; O’Neel et al., 2003] and may provide an important control on calving and subglacial melting by repeatedly circulating water beneath floating tongues [Motyka et al., 2003]. Boundary conditions at the frontal margins of tidewater glaciers provide important constraints on the balance of forces affecting ice flow and iceberg calving. For many large outlet glaciers in Greenland, the boundary condition at the calving front (floating vs grounded ice) is not well known, owing to limited knowledge of ice thickness and fjord bathymetry. Additional measurements are necessary to improve ice sheet models and sea level rise predictions.