A Subpolar Measure of the Atlantic Meridional Overturning Circulation
OSNAP is an international program designed to provide a continuous record of the full-water column, trans-basin fluxes of heat, mass and freshwater in the subpolar North Atlantic. The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East).
The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.
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OSNAP MOC Timeseries
The monthly MOC from 2014 to 2020 is derived for the full array (16.51 ± 3.3 Sv, mean±standard deviation), the OSNAP West (2.72 ± 1.34 Sv) and OSNAP East (16.35 ± 2.91 Sv) subsections. The OSNAP MOC and derived heat and freshwater transport can be accessed here.
Latest OSNAP publication on MOC interannual variability
Fu, Y., Lozier, M. S., Bower, A., Burmeister, K., Carrilho Biló, T., Cyr, F., et al. (2025). Characterizing the interannual variability of North Atlantic subpolar overturning. Geophysical Research Letters, 52, e2025GL114672. https://doi.org/10.1029/2025GL114672