Sensitivity of Simulated Arctic Ocean Salinity and Strait Transport to Interannually Variable Hydrologic Model Based Runoff

As the Arctic warms at an increased rate compared to the rest of the globe, freshwater runoff has been shown to be increasing into the Arctic Ocean. The effects of this contemporary increase in riverine freshwater into the Arctic Ocean are estimated from ocean model simulations, using two runoff data sets. One runoff data set is based on older climatological data, which has no inter-annual variability after 2007 and as such does not represent the observed increases in river runoff into the Arctic. The other data set comes from a hydrological model developed for the Arctic drainage basin, which includes contemporary changes in the climate. At the Pan-Arctic scale this new data set represents an approximately 11% increase in runoff, compared with the older climatological data. Comparing two ocean model runs forced with the different runoff data sets, overall changes in different freshwater markers across the basin were found to be between 5% and 10%, depending on the regions. The strongest increases were seen from the Siberian rivers, which in turn caused the strongest freshening in the Eastern Arctic. As the surface waters of the Arctic Ocean are sensitive to runoff, incorporating hydrological model data can help to better understand current changes and potential future impacts from increased runoff with climate change.