Search for: All records

Abstract. The role of icebergs in narrow fjords hosting marine-terminating glaciers in Greenland is poorly understood, even though iceberg melt results in asubstantial freshwater flux that can exceed the subglacial discharge. Furthermore, the melting of deep-keeled icebergs modifies the verticalstratification of the fjord and, as such, can impact ice–ocean exchanges at the glacier front. We model an idealised representation of thehigh-silled Ilulissat Icefjord in West Greenland with the MITgcm ocean circulation model, using the IceBerg package to study the effect of submarineiceberg melt on fjord water properties over a runoff season, and compare our results with available observations from 2014. We find the subglacialdischarge plume to be the primary driver of the seasonality of circulation, glacier melt and iceberg melt. Furthermore, we find that melting oficebergs modifies the fjord in three main ways: first, icebergs cool and freshen the water column over their vertical extent; second, iceberg-melt-induced changes to fjord stratification cause the neutral buoyancy depth of the plume and the export of glacially modified waters to be deeper;third, icebergs modify the deep basin, below their vertical extent, by driving mixing of the glacially modified waters with the deep-basin watersand by modifying the incoming ambient waters. Through the combination of cooling and causing the subglacial-discharge-driven plume to equilibratedeeper, icebergs suppress glacier melting in the upper layer, resulting in undercutting of the glacier front. Finally, we postulate that the impactof submarine iceberg melt on the neutral buoyancy depth of the plume is a key mechanism linking the presence of an iceberg mélange with theglacier front, without needing to invoke mechanical effects.