Estimating supraglacial lake depth in Greenland: A comparison study of empirical formula, radiative transfer and depression topography methods

Abstract Numerous supraglacial lakes form on the Greenland Ice Sheet (GrIS) during the summer, and accurately estimating their depth is crucial for understanding GrIS water storage. In this study, we estimate the depth of 35 representative GrIS supraglacial lakes using ICESat-2, Sentinel-2 imagery and ArcticDEM data. ICESat-2-derived lake depth is used to validate the performance of three remote sensing methods, namely empirical formula method (EFM), radiative transfer method (RTM) and depression topography method (DTM). EFM relies on ICESat-2-derived lake depth to construct empirical formulas, while RTM and DTM do not. The results show that (1) the green band EFM performs best; the DTM performs secondarily but tends to consistently underestimate depths; the green-band RTM has lower accuracy and overestimates depths, while the red-band RTM also has lower accuracy but underestimates depths. (2) Temporal changes of depression topography have limited impacts on the performance of DTM, whereas the uncertainties caused by lake shoreline height estimates should be considered. (3) The performance of RTM is significantly influenced by the spectral attenuation coefficient. We further identify the factors that affect spatiotemporal extrapolation of these methods and recommend prioritizing the use of the EFM when near-simultaneous ICESat-2 data are available; otherwise, DTM is recommended, yet an underestimation ratio should be used.