Danabasoglu, GokhanCastruccio, Frederic S.Boza, BurcuBarthel, Alice M.Biastoch, ArneBlaker, AdamBozec, AlexandraBruciaferri, DiegoBryan, Frank O.Chassignet, Eric P.Fu, YaoGrooms, IanGuiavarc'h, CatherineHayashida, HakaseHogg, Andrew Mc C.Holmes, Ryan M.Iovino, DoroteaciroKiss, Andrew E.Lozier, M. SusanMarques, GustavoMegann, AlexSchwarzkopf, Franziska U.Storkey, Davevan Roekel, LukeWolfe, JonXu, XiaobiaoZhang, Rong2026-07-192026-07-191991-959XWOS:001792865600001ORCID:/0000-0001-5898-7635/work/220734112https://hdl.handle.net/1885/733813405A comparison of simulated and observed overturning transports and related properties across the Overturning in the Subpolar North Atlantic Program (OSNAP) sections for the 2014-2022 period is presented, considering both depth and density space transports. The effort was motivated by the observational transport estimates at both OSNAP-West (OW) and OSNAP-East (OE) sections which show a minor role for the Labrador Sea (LS) in setting the mean and variability of the overturning in the subpolar North Atlantic. There are 9 participating groups from around the world, contributing a total of 18 ocean - sea-ice simulations with 6 different ocean models. The simulations use a common set of interannually varying atmospheric forcing datasets. The horizontal resolutions of the simulations range from nominal 1 degrees to eddy-resolving resolutions of 0.1-0.05 degrees. While there are many differences between the simulations and observations as well as among the individual simulations in terms of transport properties, the simulations show significantly larger transports at OE than at OW in agreement with the observations. Analyzing overturning circulations in both depth and density space together provides a more complete picture of the overturning properties and features. This analysis also reveals that, in both the simulations and observations, northward and southward flows substantially cancel each other at a given depth or density, producing much smaller residual (total) transports. Such cancellations tend to be much more prominent in depth space than in density space. In general, the observed transport features are captured better at OE than OW. The simulations generally show larger (smaller) transports with positive (negative) temperature and salinity biases in the upper ocean near the OSNAP sections, but with no such relationship with density biases. In high-resolution simulations, the transport profiles agree better with the observations, but challenges remain in some other metrics considered in our analysis. When transports are calculated using a density referenced to 2000 m depth, rather than the ocean surface, the relative contributions of transports at OW increase modestly.This effort at the US National Science Foundation (NSF) National Center for Atmospheric Research (NCAR) was supported by the contract 1947282 from the US Department of Energy (DOE) for the ImPACTS Project; by the grant NA18OAR4310429 from the US National Oceanic and Atmospheric Administration (NOAA), Climate Program Office (CPO), Climate Variability and Predictability Program; Modeling Analysis, Predictions, and Projections Program; the NOAA Global Ocean Monitoring and Observing (GOMO) Program; the DOE, Earth and Environmental System Modeling, Regional and Global Model Analysis Program; and by the grant OPP-2106228 from the US NSF Office of Polar Programs. The project was also partly funded by the US NSF Physical Oceanography Program by the grant OCE-2040020 for the US NSF - UK Natural Environment Research Council (NERC) project entitled "Wider Impacts of Subpolar North Atlantic Decadal Variability on the Ocean and Atmosphere (WISHBONE)". AEK was supported by the Australian Research Council (ARC) grant LP200100406. RMH was supported by the ARC grant DE21010004. AM was supported by the UK Natural Environment Research Council under the Atlantic Climate System Integrated Study (ACSIS; grant number NE/N018044/1) and the Climate Linked Atlantic Sector Science (CLASS; grant number NE/R015953/1) marine research programmes. ABl was supported by CLASS (NE/R015953/1) and the WISHBONE project (NE/T013540/1). BB was partly supported by the Turkish Scientific and Technological Research Council (TUBITAK) via an International Research Fellowship Programme for PhD Students (2214-A). MSL and YF acknowledge funding from the US NSF Physical Oceanography Program grant OCE-1948335.47enPublisher Copyright: © 2026 Gokhan Danabasoglu et al.ClimateExperimental protocolsGeneral-circulation modelGlobal oceanImpactMultidecadal variabilityOcean modelParameterizationPart iSea-ice model2026-06-1510.5194/gmd-19-5071-2026105042545281