Satellite Mapping of the Moulin Distribution Across the Entire Greenland Ice Sheet

Abstract

Moulins drain meltwater from the surface of the Greenland Ice Sheet (GrIS), affecting subglacial hydrology. However, the moulin distribution across the entire GrIS remains unclear. Using 10‐m Sentinel‐2 imagery from the summer of 2019, we manually mapped GrIS‐wide major moulins, excluding undetectable minor moulins. A total of 5,869 moulins were unevenly distributed across the six major GrIS basins; the strong‐melting southwest basin hosted the largest proportion of moulins (42.2%), while the fast‐flowing southeast basin contained the fewest (4.2%). River‐fed moulins outnumbered lake‐draining moulins (88.5% vs. 11.5%), indicating that meltwater primarily drains with diurnal variability rather than abruptly through rapid lake drainages. High‐density moulins clustered near the ice margin, whereas 6.6% extended into the accumulation zone. Furthermore, moulin density was correlated with greater meltwater runoff, lower elevations, and likely lower surface slopes. This first major moulin data set provides a critical benchmark for investigating surface‐to‐bed meltwater connections of the GrIS.