Quantifying Tidewater Glacier-Fjord Environments in the Rapidly Changing Regions of West and South Greenland

• Main Author: Baratta, Sydney
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2023
• Subjects: Fjord Circulation; Tidewater Glacier; Greenland; Icebergs; Sediment Plumes; Climate; Glaciology; Oceanography; Ilulissat; glacier; Ice Sheet; Tidewater
• Online Access: https://digitalcommons.library.umaine.edu/etd/3921; https://digitalcommons.library.umaine.edu/context/etd/article/4965/viewcontent/M_Baratta_Sydney_Dec23.pdf

The Greenland Ice Sheet has undergone rapid mass loss over the last four decades, primarily through solid and liquid discharge at marine-terminating outlet glaciers. The acceleration of these glaciers is in part due to the increase in temperature of ocean water in contact with the glacier terminus. However, quantifying meltwater injection and heat transport can be challenging due to iceberg abundance, which threatens instrument survival and fjord accessibility. Additionally, acceleration and retreat of tidewater glaciers onto land can change glacier forcing, altering fjord water-meltwater dynamics. Here, we couple in situ and remote sensing methods to quantify the upper-layer fjord dynamics in two critical regions in Greenland. In the summers of 2014 and 2019, we deployed transmitting GPS units on a total of 13 icebergs in Ilulissat Icefjord to quantify upper-layer (0 – 250 m) circulation.In the summers of 2022 and 2023, we collected 147 suspended sediment concentration measurements in fjords abutting glaciers that are in various stages of retreat. We use the suspended sediment record in south Greenland fjords to quantify surface suspended sediment load in fjords, which is generally positively correlated with meltwater runoff. Overall, we find that glacier meltwater runoff strongly impacts upper-layer fjord circulation, suspended sediment concentrations, and that glacier behavior is directly related to meltwater runoff. More specifically, we find that the direction of upper-layer fjord circulation is strongly impacted by the timing of meltwater pulses, while the circulation speed changes in concert with tidewater glacier behavior (i.e., increases and decreases in glacier speed and meltwater runoff). In fjords with retreating tidewater glaciers, we find that increases in suspended sediment concentration at the fjords surface is directly related to the timing and abundance of meltwater runoff. These studies demonstrate the utility of using surface measurementsto constrain upper-layer fjord dynamics in changing ...