Quantifying suspended sediment concentration in subglacial sediment plumes discharging from two Svalbard tidewater glaciers using Landsat-8 and in situ measurements

• Published in: International Journal of Remote Sensing
• Main Authors: Schild, Kristin M., Hawley, Robert L., Chipman, Jonathan W., Benn, Douglas I.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Svalbard; glacier; Tidewater
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/quantifying-suspended-sediment-concentration-in-subglacial-sediment-plumes-discharging-from-two-svalbard-tidewater-glaciers-using-landsat8-and-in-situ-measurements(8a183a44-aebd-4968-93b1-8ad02d0709aa).html; https://doi.org/10.1080/01431161.2017.1365388; https://research-repository.st-andrews.ac.uk/bitstream/10023/11926/1/Benn_2017_IJRS_SuspendedSediment_CC.pdf

Marine-terminating outlet glaciers discharge mass through iceberg calving, submarine melting, and meltwater run-off. While calving can be quantified by in situ and remote-sensing observations, meltwater run-off, the subglacial transport of meltwater, and submarine melting are not well constrained due to inherent difficulties observing the subglacial and proglacial environments at tidewater glaciers. Remote-sensing and in situ measurements of surface sediment plumes, and their suspended sediment concentration (SSC), have been used as a proxy for glacier meltwater run-off. However, this relationship between satellite reflectance and SSC has predominantly been established using land-terminating glaciers. Here, we use two Svalbard tidewater glaciers to establish a well-constrained relationship between Landsat-8 surface reflecance and SSC and argue that it can be used to measure relative meltwater run-off at tidewater glaciers throughout a summer melt season. We find the highest correlation between SSCs and Landsat-8 surface reflectance by using the red + NIR band combination (r 2 = 0.76). The highest correlation between SSCs and in situ field spectrometer measurements is in the 740-800 nm wavelength range (r 2 = 0.85), a spectral range not currently measured by Landsat. Additionally, we find that in situ and Landsat-8 measurements for surface reflectance of SSCs are not interchangeable and therefore establish a relationship for each detection method. We then use the Landsat-8 relationship to calculate total surface sediment load, finding a strong correlation between total surface sediment load and a proxy for meltwater run-off (r 2 ≥ 0.89). Our results establish a new metric to calculate SSCs from Landsat-8 surface reflectance and demonstrate how the SSC of subglacial sediment plumes can be used to monitor relative seasonal meltwater discharge at tidewater glaciers.