Surface Controls of Freshwater Export through Denmark Strait

Denmark Strait is a key route for the export of freshwater from the Arctic. Understanding the controls on the amount of freshwater entering the Subpolar North Atlantic is key for understanding the implications of rapid changes in the region, such as recent observed freshening of the Arctic Ocean. We present the results of an adjoint modelling study, which uses the ECCOv4 ocean state estimate to produce a reconstruction of the freshwater transport at Denmark Strait from 1992 to 2017. The reconstruction is formed of contributions from surface fluxes of buoyancy and momentum. We investigate the relative importance of these different contributions on different spatial and temporal scales. We find that surface wind stress at up to 2 years lag dominates variability. We also find a seasonally varying pattern in the dominant lags, with winter fluxes showing peak correlations with contributions from lags of up to 4 years, whereas spring fluxes showing a peak correlations on the scale of weeks.