Artificially induced melt in firn at Summit, Greenland

Summer melting in the accumulation zone of an ice sheet is imprinted in the firn as melt features. Percolating meltwater dampens seasonal variations in the snow chemistry and causes isotopic enrichment of δ18O in the snow pack, modifying the preserved record of atmospheric chemistry and interpreted paleoclimate proxies. Percolating meltwater also changes the physical structure and density profile in the firn, potentially complicating surface mass balance measurements. With the proportion of the Greenland Ice Sheet that experiences melt increasing, quantifying these impacts becomes essential. We examine the chemical and physical properties of (artificial) melt intrusion into the annual snow layer of the Greenland Ice Sheet at Summit camp across an array of 4 shallow (1.5 - 2.0 meter) snow pits. The occurrence of melt is very rare at Summit Camp. We present chemistry data (major ions, trace elements and stable water isotopes), physical stratigraphy, and Near InfraRed (NIR) imagery from the snow pits, and discuss the implications of melt intrusion on ice chemistry and firn densification. Signature of melt as detected with NIR imagery of a snowpit wall. Artificially induced melt on right, undisturbed snow on left.