Supraglacial

Supraglacial refers to anything located on the surface of a glacier or ice sheet. The term is used to describe features, processes, or materials that occur above the ice, distinguishing them from englacial (within the ice) and subglacial (beneath the ice) domains. Supraglacial conditions are governed by surface melting driven by solar radiation, air temperature, wind, and surface albedo, as well as by debris present on the ice.

Common supraglacial features include meltwater streams and rivers that flow along the glacier surface, supraglacial lakes that form in depressions, and patches of surface debris carried or deposited by rockfall. Supraglacial lakes can merge and eventually drain through subsurface conduits or boreholes, influencing the glacier’s hydrology. Debris on the surface—supraglacial debris—affects albedo and melt patterns. Thin debris layers typically reduce reflectivity and enhance melt in exposed areas, while thicker debris can act as insulation and slow surface melt.

Hydrologically, supraglacial processes interact with deeper parts of the glacier. Meltwater that pools on the surface can be routed into moulins and crevasses, joining englacial and subglacial drainage networks. This communication between surface and interior channels can affect glacier slip, ice flow, and overall mass balance, with implications for regional hydrology and sea-level rise.

Supraglacial processes are studied using field observations and remote sensing to understand surface albedo, melt rates, debris distribution, and the formation and evolution of surface water bodies. They also relate to hazards such as glacial lake outburst floods and to broader climate change impacts on ice masses.