The seasonal distribution of freshwater from meteoric sources and sea ice melt in Svalbard fjords

Accelerated retreat of glaciers in regions of the Arctic, such as Svalbard, causes the release of excess freshwater to coastal estuaries. This freshwater has a stratifying effect on the water column, thus influencing processes such as shelf exchange, heat delivery to the surface, and biological productivity. The freshwater budgets of high latitude fjord systems, however, are poorly understood, with multiple sources (including also sea ice melt and direct precipitation) contributing. The use of stable isotopes of oxygen as a water mass tracer, when measured alongside salinity, is a powerful technique for quantitatively decomposing the freshwater budget. We present a new record of glacial melt and sea-ice melt distributions during late summer and early spring from three different fjords around Svalbard using full depth profiles of oxygen isotopes. We find that glacial meltwater is widespread in the western fjords where there has been a strong influence of Atlantic water, while sea ice melt was the dominant source of freshwater to the north of the archipelago. These results are examined in the context of a simple model of the region, which is used to determine the circulation and stratification response under changing freshwater forcing conditions.