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A comprehensive simulation study of dissolved Barium and Oxygen isotope ratio in the Arctic Ocean Sha, Yingkai


The Arctic Ocean freshwater plays important roles in regional and global climate. Dissolved Barium and the Oxygen isotope ratio are two tracers that provide key information on the river runoff and the sea-ice melt water as two Arctic Ocean freshwater components. In this research, an offline tracer model was developed with dissolved Barium and Oxygen isotope ratio modules and appropriate boundary conditions were applied to the Arctic Ocean to simulate the spatial and temporal variations of the two tracers. The tracer model was run from 2002 to 2013 after a 24-year spin-up. The simulation results show reasonable tracer climatology and seasonal cycles, agree well with field observations and the Arctic freshwater cycle. The tracer model was applied to investigate the atmospheric driven freshwater variabilities in the upper 130m through linear trend and Empirical Orthogonal Function (EOF) analysis. The linear trend result shows the increase in the transport of Eurasian runoff from the Makarov Basin to the Beaufort Sea and concurrent with the increase in the winter-spring Arctic Oscillation (AO). The three EOF modes show the role of the dipole anomaly, the interannual impact of the North Atlantic Oscillation (NAO) and the Beaufort Sea anticyclonic anomalous wind, respectively on changing the pathway of the high Barium concentration North American runoff and the impact of the Eurasian runoff along the continental shelves and in the central Arctic. A case study of the Beaufort Gyre freshwater in 2007-2008 revealed the change of Eurasian runoff pathways in three stages with the dipole anomaly and the transport of Eurasian runoff in the developing stage, the strong anti-cyclonic wind in the Beaufort Sea in the mature stage and the weakening of the Beaufort Gyre in the final stage. A linear mixing model result confirms the increase of the Eurasian runoff in the Beaufort Gyre in the winter of 2007.

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