Abstract Greenland's fjords are the gateways through which the Greenland Ice Sheet (GrIS) interacts with the open ocean. These fjords are projected to undergo significant change as glaciers retreat with implications ranging from impacts to local fisheries and infrastructure to global sea level rise. Icebergs discharged by marine‐terminating glaciers in these fjords progressively melt on their way out of the fjord. Studies have shown that the cooling/freshening of the water column by icebergs contributes to the fjord overturning circulation. However, the majority of these studies are focused on summer conditions when data exist, and little is known about the impact and melting of icebergs year‐round. Here, we use a realistic regional configuration of a numerical model (MITgcm) of Sermilik fjord in southeast Greenland, from 2015 to 2017, to show that iceberg melting occurs year‐round, is focused in the upper 100 m of the water column, and largely occurs in the mélange region near the glacier. Comparison with an identical run without icebergs shows that upwelling induced by subsurface iceberg melt drives a warming (°C) of the surface layer in spring/winter in the entire fjord. This mélange upwelling supports a year‐round overturning circulation. Overall, our findings emphasize that icebergs must be included in simulations of fjords in order to correctly simulate water properties and circulation, including upwelling and heat flux. Representing these dynamics accurately is critical for understanding the impacts of icebergs on glacial melt rates and the interactions between glacial fjords, the GrIS, and the open ocean.
Kinne et al. (Fri,) studied this question.