The annual salinity cycle of the Denmark Strait Overflow

The Denmark Strait Overflow (DSO) is an important source of dense water input to the deep limb of the Atlantic Meridional Overturning Circulation. It is fed by separate currents from the north that advect dense water masses formed in the Nordic Seas and Arctic Ocean which then converge at Denmark Strait. Here we identify an annual salinity cycle of the DSO, characterized by freshening in winter and spring. The freshening is linked to freshening of the Shelfbreak East Greenland Current in the Blosseville Basin north of the Denmark Strait. We demonstrate that the East Greenland Current advects fresh pycnocline water above the recirculating Atlantic Water, which forms a low salinity lid for the overflow in Denmark Strait and in the Irminger Basin. This concept is supported by intensified freshening of the DSO in lighter density classes on the Greenland side of the overflow. The salinity of the DSO in the Irminger Basin is significantly correlated with northerly/northeasterly winds in the Blosseville Basin at a lag of 3-4 months, consistent with estimated transit times. This suggests that wind driven variability of DSO source water exerts an important influence on the salinity variability of the downstream DSO, and hence the composition of the deep limb of the Atlantic Meridional Overturning Circulation.

Details

Publication status:
Published
Author(s):
Authors: Opher, J.G. ORCIDORCID record for J.G. Opher, Brearley, J.A. ORCIDORCID record for J.A. Brearley, Dye, S.R., Pickart, R.S., Renfrew, I.A., Harden, B.E., Meredith, M.P. ORCIDORCID record for M.P. Meredith

On this site: Jacob Opher, Alexander Brearley, Michael Meredith
Date:
1 April, 2022
Journal/Source:
Journal of Geophysical Research: Oceans / 127
Page(s):
23pp
Link to published article:
https://doi.org/10.1029/2021JC018139