(Global Positioning System)
GPS is a global navigation satellite system that provides location and time information. POLENET GPS sites are generally installed on bed rock. Because most of the polar regions are covered with a thick, icy blanket, these stations tend to be established on nunataks. Nunataks are isolated peaks of rock projecting above a surface of ice or snow. The GPS sites register incoming microwave signals from satellites. Over time, whether it is a result of plate tectonics or glacial isostatic adjustment (crustal movement caused by the melting of and consequential release from the weight of the polar ice), the GPS equipment records the slightest movement of the surface from its original location and the data is then processed for science team members to measure and analyzed.
Learn more at UNAVCO: http://facility.unavco.org/project_support/polar/remote/remote.html