Abstract:
Continuous measurements from the OSNAP (Overturning in the Subpolar North Atlantic Program) array have yielded the first estimates of trans-basin heat and salinity transports in subpolar latitudes. For the period from August 2014 to May 2018, there is a poleward heat transport of 0.50 ± 0.05 PW and a poleward salinity transport of 12.5 ± 1.0 Sv across the OSNAP section. Based on the mass and salt budget analyses, we estimate that a surface freshwater input of 0.36 ± 0.04 Sv over the broad subpolar-Arctic region is needed to balance the ocean salinity change created by the OSNAP transports. The overturning circulation is largely responsible for setting these heat and salinity transports (and the derived surface freshwater input) derived from the OSNAP array, while the gyre (isopycnal) circulation contributes to a lesser, but still significant, extent. Despite of its relatively weak overturning and heat transport, the Labrador Sea is a strong contributor to salinity and freshwater changes in the subpolar region. Combined with trans-basin transport estimates at other locations, we provide new estimates for the time-mean surface heat and freshwater divergences over a wide domain of the Arctic-North Atlantic region to the north and south of the OSNAP line. Furthermore, we estimate the total heat and freshwater exchanges across the surface area of the extratropical North Atlantic between the OSNAP and the RAPID-MOCHA (RAPID Meridional Overturning Circulation and Heat-flux Array) arrays, by combining the cross-sectional transports with vertically-integrated ocean heat and salinity content. Using our ocean observation-based estimates as ground-truth, we find significant biases in the air-sea heat and freshwater fluxes from atmospheric reanalysis products (NCEP CFS2, JRA55, ERA5).
Bio:
Feili Li is a physical oceanographer, whose research focuses on the ocean’s role in the Earth’s climate system. Feili studies the large-scale meridional overturning circulation of the ocean and how that circulation affects the redistribution of heat and salt (or freshwater) from one part of the ocean to another. Feili received his Ph.D. from the University of Delaware and had worked at the Duke University and the Georgia Institute of Technology before joining the faculty of the MEL and COE in February 2021.
Conference ID (For ZOOM)：1887235214
Suihui (随会) Link：https://private.suimeeting.com/share/j/1887235214
