Non-surface mass balance of glaciers in Iceland

Publisher's version (útgefin grein)Non-surface mass balance is non-negligible for glaciers in Iceland. Several Icelandic glaciers are in the neo-volcanic zone where a combination of geothermal activity, volcanic eruptions and geothermal heat flux much higher than the global average lead to basal melting close to 150 mm w.e. a−1 for the Mýrdalsjökull ice cap and 75 mm w.e. a−1 for the largest ice cap, Vatnajökull. Energy dissipation in the flow of water and ice is also rather large for the high-precipitation, temperate glaciers of Iceland resulting in internal and basal melting of 20–150 mm w.e. a−1. The total non-surface melting of glaciers in Iceland in 1995–2019 was 45–375 mm w.e. a−1 on average for the main ice caps, and was largest for Mýrdalsjökull, the south side of Vatnajökull and Eyjafjallajökull. Geothermal melting, volcanic eruptions and the energy dissipation in the flow of water and ice, as well as calving, all contribute, and thus these components should be considered in mass-balance studies. For comparison, the average mass balance of glaciers in Iceland since 1995 is −500 to −1500 mm w.e. a−1. The non-surface mass balance corresponds to a total runoff contribution of 2.1 km3 a−1 of water from Iceland.Financial support for lidar mapping of glaciers in Iceland in 2008–2012 was provided by the Icelandic Research Fund (163391-052), the Landsvirkjun (National Power Company of Iceland) Research Fund, the Icelandic Road Administration, the Reykjavík Energy Environmental and Energy Research Fund, the National Land Survey of Iceland, the Klima- og Luftgruppen (KoL) research fund of the Nordic Council of Ministers, and the Vatnajökull National Park. The acquisition of the Hofsjökull 2013 DEM was funded by AlpS GmbH and the University of Innsbruck. The acquisition of the Langjökull 2013 DEM was funded by NERC grant IG 13/12 and the DEM was provided by Ian Willis at the Scott Polar Research Institute. The work on estimating geothermal and volcanic power is based on funding from many sources, including the Research Fund of the University of Iceland, ISAVIA (the Icelandic Aviation Service), the Icelandic Road Administration and Landsvirkjun; logistical support has been provided by the Iceland Glaciological Society.Peer Reviewe