The annual salinity cycle of the Denmark Strait Overflow

Thumbnail Image
Date
2022-03-22
Authors
Opher, Jacob G.
Brearley, J. Alexander
Dye, Stephen R.
Pickart, Robert S.
Renfrew, Ian A.
Harden, Benjamin E.
Meredith, Michael P.
Alternative Title
Date Created
Location
DOI
10.1029/2021jc018139
Related Materials
Replaces
Replaced By
Keywords
Overflow
Salinity
Seasonality
Fresh lid
Advection
Abstract
The Denmark Strait Overflow (DSO) is an important source of dense water input to the deep limb of the Atlantic Meridional Overturning Circulation (AMOC). 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 AMOC.
Description
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Opher, J., Brearley, J., Dye, S., Pickart, R., Renfrew, I., Harden, B., & Meredith, M. The annual salinity cycle of the Denmark Strait Overflow. Journal of Geophysical Research: Oceans, 127(4), (2022): e2021JC018139, https://doi.org/10.1029/2021jc018139.
Embargo Date
Citation
Opher, J., Brearley, J., Dye, S., Pickart, R., Renfrew, I., Harden, B., & Meredith, M. (2022). The annual salinity cycle of the Denmark Strait Overflow. Journal of Geophysical Research: Oceans, 127(4), e2021JC018139.
Cruises
Cruise ID
Cruise DOI
Vessel Name
Except where otherwise noted, this item's license is described as Attribution 4.0 International