Branch Seminar Series: Wei Li Wang

SGT, Code 614.1
Measurements of ice velocities in the marginal regions of Greenland ice sheet have shown a melt-acceleration effect (Zwally et al., 2002). Water from surface melting rapidly penetrates to the bed through moulins and crevasses and increases the ice flow due to the enhanced basal lubrication and sliding. A 3-dimensional time-dependent ice flow model is applied to the Greenland ice sheet to investigate the dynamic response to climate change from the melt-acceleration effect. The model incorporates a seasonal basal sliding parameterization that depends on estimates of the meltwater penetration to the bed. The surface meltwater production is estimated using satellite observed surface temperatures during the time period of 1982 -2006. The model results show that the ice dynamic thinning is felt not only at the margins, but also on the inland ice sheet. The modeled mass loss due to the ice dynamic response to the increased seasonal basal sliding is about 20% of the total ice-sheet mass loss observed from ICESat (2003-2006). In the past 25 years, ice-sheet thinning rates have increased along with the accelerated basal flow, with a more rapid increase within the last 5 years.