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1. Examining the Origins of Ocean Heat Content Variability in the Eastern North Atlantic Subpolar Gyre

   https://doi.org/10.1029/2018GL079122  

   Foukal, Nicholas P. ; Lozier, M. Susan ( October 2018 , Geophysical Research Letters)
2. Reduction in Ocean Heat Transport at 26°N since 2008 Cools the Eastern Subpolar Gyre of the North Atlantic Ocean

   https://doi.org/10.1175/JCLI-D-19-0323.1  

   Bryden, Harry L. ; Johns, William E. ; King, Brian A. ; McCarthy, Gerard ; McDonagh, Elaine L. ; Moat, Ben I. ; Smeed, David A. ( March 2020 , Journal of Climate)

   Abstract Northward ocean heat transport at 26°N in the Atlantic Ocean has been measured since 2004. The ocean heat transport is large—approximately 1.25 PW, and on interannual time scales it exhibits surprisingly large temporal variability. There has been a long-term reduction in ocean heat transport of 0.17 PW from 1.32 PW before 2009 to 1.15 PW after 2009 (2009–16) on an annual average basis associated with a 2.5-Sv (1 Sv ≡ 106 m3 s−1) drop in the Atlantic meridional overturning circulation (AMOC). The reduction in the AMOC has cooled and freshened the upper ocean north of 26°N over an area following the offshore edge of the Gulf Stream/North Atlantic Current from the Bahamas to Iceland. Cooling peaks south of Iceland where surface temperatures are as much as 2°C cooler in 2016 than they were in 2008. Heat uptake by the atmosphere appears to have been affected particularly along the path of the North Atlantic Current. For the reduction in ocean heat transport, changes in ocean heat content account for about one-quarter of the long-term reduction in ocean heat transport while reduced heat uptake by the atmosphere appears to account for the remainder of the change in ocean heat transport. 

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3. Circulation and overturning in the eastern North Atlantic subpolar gyre

   https://doi.org/10.1016/j.pocean.2022.102884  

   Koman, G. ; Johns, W.E. ; Houk, A. ; Houpert, L. ; Li, F. ( November 2022 , Progress in Oceanography)
4. Structure and Transport of the North Atlantic Current in the Eastern Subpolar Gyre From Sustained Glider Observations

   https://doi.org/10.1029/2018JC014162  

   Houpert, L. ; Inall, M. E. ; Dumont, E. ; Gary, S. ; Johnson, C. ; Porter, M. ; Johns, W. E. ; Cunningham, S. A. ( August 2018 , Journal of Geophysical Research: Oceans)
5. Role of Air-sea Fluxes and Ocean Surface Density in the Production of Deep Waters in the Eastern Subpolar Gyre of the North Atlantic

   https://doi.org/10.5194/os-17-1353-2021  

   Petit, Tillys ; Lozier, Susan M. ; Josey, Simon A. ; Cunningham, Stuart A. ( October 2021 , Ocean science)

   Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of North Atlantic Deep Water. Dense water formation in these basins is mainly explained by buoyancy forcing that transforms surface waters to the deep waters of the AMOC lower limb. Air-sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation. We analyze these contributions to the transformation in order to better understand the connection between atmospheric forcing and the densification of surface water. More precisely, we study the impact of air-sea fluxes and the ocean surface density field on the transformation of subpolar mode water (SPMW) in the Iceland Basin, a water mass that “pre-conditions” dense water formation downstream. Analyses using 40 years of observations (1980–2019) reveal that the variance in SPMW transformation is mainly influenced by the variance in density at the ocean surface. This surface density is set by a combination of advection, wind-driven upwelling and surface fluxes. Our study shows that the latter explains ∼ 30 % of the variance in outcrop area as expressed by the surface area between the outcropped SPMW isopycnals. The key role of the surface density in SPMW transformation partly explains the unusually large SPMW transformation in winter 2014–2015 over the Iceland Basin. 

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