Publication Date:
2022-05-27
Description:
Author Posting. © American Meteorological Society, 2021. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 51(3), (2021): 955–973, https://doi.org/10.1175/JPO-D-20-0240.1.
Description:
Fresh Arctic waters flowing into the Atlantic are thought to have two primary fates. They may be mixed into the deep ocean as part of the overturning circulation, or flow alongside regions of deep water formation without impacting overturning. Climate models suggest that as increasing amounts of freshwater enter the Atlantic, the overturning circulation will be disrupted, yet we lack an understanding of how much freshwater is mixed into the overturning circulation’s deep limb in the present day. To constrain these freshwater pathways, we build steady-state volume, salt, and heat budgets east of Greenland that are initialized with observations and closed using inverse methods. Freshwater sources are split into oceanic Polar Waters from the Arctic and surface freshwater fluxes, which include net precipitation, runoff, and ice melt, to examine how they imprint the circulation differently. We find that 65 mSv (1 Sv ≡ 106 m3 s−1) of the total 110 mSv of surface freshwater fluxes that enter our domain participate in the overturning circulation, as do 0.6 Sv of the total 1.2 Sv of Polar Waters that flow through Fram Strait. Based on these results, we hypothesize that the overturning circulation is more sensitive to future changes in Arctic freshwater outflow and precipitation, while Greenland runoff and iceberg melt are more likely to stay along the coast of Greenland.
Description:
We gratefully acknowledge the U.S. National Science Foundation: this work was supported by Grants OCE-1258823, OCE-1756272, OCE-1948335, and OCE-2038481. L.H.S. thanks the U.S. Norway Fulbright Foundation for the Norwegian Arctic Chair Grant 2019-20 that made the visit to Scripps Institution of Oceanography possible. N.P.H. acknowledges support by the U.K. Natural Environment Research Council (NERC) National Capability program CLASS (NE/R015953/1), and Grants U.K.-OSNAP (NE/K010875/1, NE/K010875/2) and U.K.-OSNAP Decade (NE/T00858X/1). We acknowledge the World Climate Research Programme, which, through its Working Group on Coupled Modelling, coordinated and promoted CMIP6.
Keywords:
Arctic
;
North Atlantic Ocean
;
Conservation equations
;
Meridional overturning circulation
;
Ocean circulation
;
Inverse methods
Repository Name:
Woods Hole Open Access Server
Type:
Article
