December 11, 2017
The theme changes from a glaciers to a glaciologists perspective with a focus on selected work at the AGU 2017. The research discussed here is from the Poster Paper sessions the most interactive part of the convention. The following are some interesting snapshots of the breadth and depth of ongoing research. The most compelling figure from each poster is used.
Richard Forster, U of Utah team presented work on the firn aquifer in Greenland. A feature we did not even know existed until 2011. They have conducted four field seasons, using ground penetrating radar and magnetic resonance soundings to map water table elevation, thickness and volume in several areas. They found the aquifer thickness has a typical thickness of 10-30 m. Further they found that firn aquifers have existed since at least 1993 and have expanded and shifted with time see above image.
Kristin Poinar, NASA GSFC team examined the drainage of supraglacial lakes in Greenland. They investigated factors that control when and where the lakes drain to the ice sheet base. They observed 359 lake drainage events in a west Greenland region and compare the dates of these drainage events to strain rates calculated from satellite data. They noted both slow draining and fast draining lakes, the faster drainages occurring later in the summer on average. They found that strain rates did not satisfactorily predict lake drainage date.
Vena Chu at UC-Santa Barbara’s team mapped river networks On Russell Glacier that terminate into moulins which connect surface melt to englacial and subglacial drainage networks. They used WorldView imagery to show development of molins and their migration between 2012 and 2015. The majority of moulins they mapped in 2015 were moulins in 2012. New moulins most commonly formed in crevassed, thinner ice areas near the ice margin, and a lesser but significant quantity at higher elevations above 1300 m.
Rohi Muthyala, Rutgers University team measured the discharge of supraglacial streams for three months, constructing rating curves. They compared air temperature and discharge in the upper and lower basin. The upper basin was more related to the daily air temperature. The stream system feeds into a moulin system.
Mariah Radue, University of Maine’s team mapped and dated the moraines and erratics adjacent to Potanin Glacier in the Mongolian Altai (49°N, 88°E). They used 10Be surface-exposure chronology to date glacial landforms mapped using satellite and Drone imagery. Based on our glacial reconstruction, we estimate changes in atmospheric temperature from the Last Glacial Maximum to the Late Holocene using snowline reconstruction techniques. Mongolia is a unique location because it is isolated from oceanic influences and a climate could provide insight into the roles of local radiation forcing from earth orbital changes, greenhouse gases, and a Asian climate dynamics.
Konstanz Haubner, with a team from GEUS in Denmark provided a model simulating velocity and ice thickness change at Upernavik Glacier, Greenland from 1849-2017. In the image above the retreat is illustrated, separating into three separate glaciers with a more bedrock pinning points to stabilize. They noted a changing contribution to Upernavik’s ice mass loss from surface melt and ice dynamics in different time periods.