A high-resolution pan-Arctic meltwater discharge dataset from 1950 to 2021

Abstract. Arctic air temperatures have increased approximately 4 times faster than the global average since about 1980. Consequently, the Greenland ice sheet has lost approximately twice as much ice as the Antarctic ice sheet between 2003 and 2019, and mass loss from glaciers and ice caps is also dominated by those that lie in the Arctic. Thus, Arctic land ice loss is currently a major contributor to global sea level rise. This increasing freshwater flux into the Arctic and North Atlantic oceans, will also affect physical, chemical and biological processes across a range of domains and spatiotemporal scales. To date, meltwater discharge data at Arctic coastlines are only available from two datasets that are limited by their spatial resolution and/or coverage. Here, we extend previous work and provide a high-resolution coastal meltwater discharge data product that covers all Arctic regions, where land ice is present, i.e. the Canadian Arctic Archipelago, Greenland, Iceland, Svalbard, Russian Arctic islands. Coastal meltwater discharge data – i.e. spatially integrated runoff that is assigned to the outflow points of drainage basins – were derived from Modèle Atmosphérique Régional (MAR) daily ice and land runoff products between 1950 and 2021, which we statistically downscaled from their original approximately 6 km resolution to 250 m. The complete data processing algorithm, including downscaling, is fully documented and relies on open-source software. The coastal discharge database is disseminated in easily accessible and storage efficient netCDF files (Igneczi and Bamber, 2024; https://doi.org/10.1594/PANGAEA.967544).