V. W. Chu et al., J. Glaciol., 55 (2009), Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

Journal of Glaciology, Vol. 55, No. 195 (2009), pp. 1072-1082

Sediment plume response to surface melting and supraglacial lake drainages on the Greenland ice sheet

Vena W. Chu* (Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Box 951524, Los Angeles, CA 90095-1524, U.S.A.), Laurence C. Smith (Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Box 951524, Los Angeles, CA 90095-1524, U.S.A.), Asa K. Rennermalm (Department of Geography, University of California, Los Angeles, 1255 Bunche Hall, Box 951524, Los Angeles, CA 90095-1524, U.S.A.), Richard R. Forster (Department of Geography, University of Utah, 260 S. Central Campus Drive, Salt Lake City, UT 84112, U.S.A.), Jason E. Box (Department of Geography, Ohio State University, 1036 Derby Hall, 154 North Oval Mall, Columbus, OH 43210-1361, U.S.A.), and Niels Reeh (Danish National Space Center, Technical University of Denmark, Ørsteds Plads Building 348, DK-2800 Kgs. Lyngby, Denmark)

Abstract

Increased mass losses from the Greenland ice sheet and inferred contributions to sea-level rise have heightened the need for hydrologic observations of meltwater exiting the ice sheet.We explore whether temporal variations in ice-sheet surface hydrology can be linked to the development of a downstream sediment plume in Kangerlussuaq Fjord by comparing: (1) plume area and suspended sediment concentration from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and field data; (2) ice-sheet melt extent from Special Sensor Microwave/Imager (SSM/I) passive microwave data; and (3) supraglacial lake drainage events from MODIS. Results confirm that the origin of the sediment plume is meltwater release from the ice sheet. Interannual variations in plume area reflect interannual variations in surface melting. Plumes appear almost immediately with seasonal surface-melt onset, provided the estuary is free of landfast sea ice. A  seasonal hysteresis between melt extent and plume area suggests late-season exhaustion in sediment supply. Analysis of plume sensitivity to supraglacial events is less conclusive, with 69% of melt pulses and 38% of lake drainage events triggering an increase in plume area. We conclude that remote sensing of sediment plume  behavior offers a novel tool for detecting the presence, timing and interannual variability of meltwater release from the ice sheet. 

*Correspondence e-mail:  venachu@ucla.edu

Link:  http://www.igsoc.org/journal/55/194/j09j025.pdf