Seasonally evolving hydraulic transmissivity beneath Greenland supraglacial lakes [post]

Ching-Yao Lai, Laura Stevens, Danielle Chase, Timothy Creyts, Mark Behn, Sarah Das, Howard Stone
2020 unpublished
Surface meltwater reaching the base of the Greenland Ice Sheet transits through drainage networks, modulating the flow of the ice sheet. Dye-tracing studies indicate that drainage efficiency evolves seasonally along the drainage pathway. However, the local evolution of drainage systems further inland, where ice thicknesses exceed 1000 m, remains largely unknown. Here, we develop a novel method to infer transmissivity of the drainage system based on surface uplift relaxation following rapid lake
more » ... ollowing rapid lake drainage events. Combining field observations of five lake drainage events with a mathematical model and laboratory experiments, we show that the surface uplift decreases exponentially with time, as the water in the blister formed beneath the drained lake permeates through the subglacial drainage system. This deflation obeys a universal relaxation law with a timescale that reveals hydraulic transmissivity and indicates a two-order-of-magnitude increase in subglacial transmissivity as the melt season progresses, suggesting significant changes in basal hydrology beneath the lakes.
doi:10.21203/ fatcat:xix5wnktyrh4rmq2wnphgnadtu