Direct Evidence of Meltwater Flow Within a Firn Aquifer in Southeast Greenland

摘要: Within the lower percolation zone of southeastern Greenland ice sheet, meltwater has accumulated within firn pore space, forming extensive aquifers. Previously, it was unclear if these aquifers stored or facilitated runoff. Following mixing a saline solution into boreholes aquifer, we observe that specific conductance measurements decreased over time as flowing freshwater diluted mixture in borehole. These tests indicate water flows through aquifer with an average discharge 4.3 × 10−6 m/s (σ = 2.5 × 10−6 m/s). The decreases dramatically to 0 m/s, defining bottom between 30 50 m depth. observed flow indicates space is short-term (<30 years) storage mechanism this region. Meltwater out likely nearby crevasses, and possibly down base sheet ocean.