The role of freshwater in Arctic fjords described using isotopes of oxygen (and some small amount of modelling)
Defining the role of freshwater in a fjord is important to further our understanding of seasonal physical variability in fjordic systems because the variability of freshwater flux is a key control on fjord oceanography, yet information on freshwater inputs to high-latitude fjords is currently lacking. In this study, two methods of studying fjords were utilised. Firstly, seawater samples and oceanographic profiles were collected from four fjords and shelves around the high-Arctic Svalbard archipelago between summer 2013 and spring 2015. Four contrasting regions of freshwater influence around the Svalbard archipelago were then established, defined by their freshwater processes. Further analysis of data suggest that coastal currents act as an upstream freshwater source, and are also enhanced by freshwater along their path. Upper layer circulation, meanwhile, was seen to be an important mode of dispersal of freshwater inputs from smaller inlets. Secondly, a box model was modified by the inclusion of a sea ice model and was run to understand the leading-order processes and mechanisms observed in Arctic fjords. Model results were validated against four years of oceanographic data from a mooring deployed from 2008–2013 in a silled glaciated fjord. The model showed that varying the sill geometry of a high-Arctic fjord impacts the formation of sea-ice and the dominant modes of exchange. The model also showed that warming of the sub-surface temperature causes excess heat inside fjords, which impacts on sea-ice production and is highly likely to cause accelerated melting of tidewater glaciers.