Reply on RC2

Abstract

Direct measurements of glacier hydrological processes are usually restricted to short periods and a limited number of sites due to logistical, financial, and meteorological constraints. As a result, the indirect study of glacier hydrology through remote sensing has gained traction while the accessibility of high-resolution publicly available remote sensing data has also increased. By quantifying the areal extents of key dynamic features of a tidewater glacier (i.e. the evolution of sea ice, supraglacial lakes, meltwater plumes) as proxies of its hydrological cycle using Sentinel-2 observations, a simple alternative amidst the outlined logistical constraints is potentially available. Here we demonstrate the usefulness of Sentinel-2 satellite images as a simple and accessible tool with high temporal coverage for studying glacier hydrology. To make this case for the Nordenskiöld tidewater glacier, the evolution of its supraglacial hydrological system and respective meltwater plumes areal extents were monitored for the 2016–2020 melting seasons. Hydrological connectivity of supra- and subglacial systems and the resulting meltwater plumes are illustrated. Meltwater is stored on the glacier surface at the beginning of the melt season (June) which is observed through the filling of the supraglacial lakes. The stored meltwater is later released (June/July), probably through englacial conduits and moulins, and consequently reaches the subglacial drainage system. The resulting occurrence of meltwater plumes clearly indicates the latter in Adolfbukta at the glacier terminus. This signals the transport of significant volumes of water in contact with the glacier bed. The meltwater plume activity peaks during late July, and its appearance continues until mid-September. The duration of the glacier melt season is reflected through the filling of supraglacial lakes and later in the appearance of meltwater plumes. The temporal pattern of the hydrologic processes is relatively uniform during the study period, contrasting the large variability of sea ice cover duration. The observed behavior of Nordenskiöld’s supraglacial lakes is in good agreement with similar tidewater glaciers in Svalbard.