Pre-melt-season sediment plume variability at Jökulsárlón, Iceland, a preliminary evaluation using in-situ spectroradiometry and satellite imagery

High-latitude atmospheric warming is impacting freshwater cycling, 2 requiring techniques for monitoring the hydrology of sparsely-gauged regions. 3 The submarine runoff of tidewater glaciers presents a particular challenge. We 4 evaluate the utility of Moderate Resolution Imaging Spectroradiometer (MODIS) 5 imagery for monitoring turbid meltwater plume variability in the glacier lagoon 6 Jökulsárlón, Iceland, for a short interval before the onset of the main melt 7 season. Total Suspended Solids concentrations (TSS) of surface waters are 8 related to remotely-sensed reflectance via empirical calibration between in-situ-9 sampled TSS and reflectance in a MODIS band 1-equivalent wavelength window. 10 This study differs from previous ones in its application to an overturning 11 tidewater glacier plume, rather than one derived from river runoff. The linear 12 calibration improves on previous studies by facilitating a wider range of plume 13 metrics than areal extent, notably pixel-by-pixel TSS values. Increasing values of 14 minimum plume TSS over the study interval credibly represent rising overall 15 turbidity in the lagoon as melting accumulates. Plume extent responds 16 principally to consistently-strong offshore winds. Further work is required to 17 determine the temporal persistence of the calibration, but remote plume 18 observation holds promise for monitoring hydrological outputs from ungauged 19 or ungaugeable systems.