Coastal meltwater plume detection and its response to melting variations around the Greenland Ice Sheet

• Main Author: Guo, Wenkai
• Format: Master Thesis
• Language: English
• Published: University of Cambridge 2015
• Subjects: Greenland; Ice Sheet; Sea ice
• Online Access: https://doi.org/10.17863/CAM.35450; https://www.repository.cam.ac.uk/handle/1810/288133

Meltwater runoff is an important component of the mass balance of the Greenland ice sheet and is usually assessed using climate-mass balance models. In-situ measurements of runoff from the outlets are rare, and remote sensing platforms capable of monitoring runoff in rivers, lakes and fjords are in their infancy. Thus, there is a need to investigate new methods of observing meltwater losses. Preliminary studies have been conducted correlating measured meltwater discharge to different characteristics of plumes containing suspended sediment in fjords retrieved from remote sensing. However, suspended sediments are not directly representative of meltwater leaving the ice sheet, and later in the melt season the meltwater may have a very low sediment load due to exhaustion in sediment supply. Also, the spatial resolution of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery used in these studies limits the accuracy of sediment plume retrieval, especially in areas of pervasive iceberg and sea ice cover. For non-glacial environments, there have been successful attempts at delineating freshwater plumes in the ocean by their surface salinity and thermal signatures achieved from satellite imagery. For my MPhil dissertation, I propose to use multi-year Landsat data to derive a time series of water plume location, size and shape using proxies for identifying suspended sediment, salinity and thermal signals in several fjords in Greenland. Seasonal and inter-annual variations in the location, size and shape of the various plumes will then be compared against variations in ice-sheet melt extent achieved from Special Sensor Microwave/Imager (SSM/I) passive microwave data and cumulative melt derived from a positive degree model in order to examine the correlations between ice sheet melting and the delivery of water to the ice sheet margins.