Science / project summary
The melting of the Greenland ice sheet is not a simple issue of warmer air temperatures melting the surface ice, which then flows into the ocean. Surface meltwater can flow deep into the glacier through natural pipes known as moulins. These subsurface channels not only transmit water to some outlet, where it flows into the ocean, but may also influence the downslope sliding of the glacier toward the ocean. To better understand the controls that govern glacier sliding, the researchers will conduct field and model studies on the Greenland ice sheet. Researchers will instrument a number of moulins with pressure sensors. Glacier velocity will be measured with GPS sensors. Discharge will be monitored through dye tracing. Simulations will be conducted to integrate the observations with a number of simple ‘conduit’ models in the hope of providing a better and more comprehensive understanding of the processes that govern glacier sliding. Beyond the training of graduate and undergraduate students, the researchers will work with a journalism student at the University of Arkansas to produce a documentary about their field experience. This collaboration provides a unique opportunity to communicate to the general public. It is thought that increased channelization reduces subglacial water pressure and acts to buffer the Greenland Ice Sheet (GrIS) against large increases in ice velocity. However, few measurements of water pressure have been made in channelized subglacial drainage systems to test this hypothesis. The researchers will obtain synoptic supraglacial stream discharge data, moulin water level and ice velocity at two moulin sites along an ice flow line in the Paakitsoq Region of the GrIS. Data will be analyzed, and used to parameterize model experiments, to determine the degree to which: 1) local versus regional inputs of melt water control moulin water levels; 2) changes in effective pressure that occur along ice flow paths affect local relationships between subglacial water pressure and ice velocity.