Olivé Abelló et al., 2025 dataset - Direct pathways from the Drake Passage to the South Atlantic subtropical gyre

Lagrangian simulations based on 18 years (2002-2019) of high-resolution thermohaline and three-dimensional velocity fields allow revisiting the fate and thermohaline changes of the upper-ocean Antarctic Circumpolar Current (ACC) waters that enter directly the South Atlantic Ocean basin. An advection-diffusion scheme, applied to both climatological annual-mean and daily-mean fields, allows estimating the mean pathways and seasonal variability, as well as recirculation volume transports, times and depths in the South Atlantic Subtropical Gyre (SASG). The annual-mean diffusive simulation shows that 96.5 Sv of the upper-ocean waters (up to the 28.00 kg m-3) crossing the Drake Passage remain in the ACC, while 13.0 Sv join the eastern margin of the SASG. Of these, 8.6 Sv plus an additional 2.7 Sv reach the North Brazil Current, yielding a total Drake contribution of 11.2 Sv to the upper returning-limb of the Atlantic Meridional Overturning Circulation. The upper-ocean waters that reach the eastern SASG undergo substantial water mass transformations, with a net transfer of 6.7 Sv from intermediate-deep to surface layers and an increase in heat transport by 0.39 PW and salt transport by 8.5 × 106 kg s-1, but remain largely unchanged as they drift westward toward the western boundary at 21°S. Most waters within the SASG (86%) recirculate once, taking a median of 9.1 ± 9.0 years, although some complete as many as three loops after reaching 32°S-W. Regarding seasonality, the transit times and transport fraction of the upper-ocean waters flowing into the SASG show higher variability than those remaining in the ACC path. The dataset contains the Lagrangian particle outputs generated directly from Parcels v2, without any post-processing, for climatological annual-mean diffusive, daily-mean diffusive, annual-mean non-diffusive, and 18-year daily non-diffusive simulations. Annual_mean_diffusive_particles.nc: Lagrangian particles tracked using a climatological annual-mean simulation with horizontal diffusion (kh > 0) over a 75-year period. Annual_mean_nondiffusive_particles.nc: Lagrangian particles tracked using a climatological annual-mean simulation without horizontal diffusion (kh = 0) over a 75-year period. Daily_18y_nondiffusive_particles.nc: Lagrangian particles tracked using original GLORYS12v1 daily fields (2002–2019), without horizontal diffusion (kh = 0) over a 75-year period. Daily_mean_diffusive_4d_[MMDD].nc: Lagrangian particles tracked and released every 4 days using climatological daily-mean fields with diffusion (kh > 0) over a 75-year period. [MMDD] corresponds to the month and day on which particles were released. Please read the README.rt file for further details. Cite the preprint as: Anna Olivé Abelló, Josep L Pelegrí, Mariona Claret. Direct pathways from the Drake Passage to the South Atlantic subtropical gyre. ESS Open Archive. July 15, 2024. DOI: 10.22541/essoar.172107873.36398970/v1 This work has been funded by the Spanish Government through projects SAGA (Ministerio de Ciencia, Innovación y Universidades, reference RTI2018-100844-B-C33) and SACO-SO (Ministerio de Ciencia e Innovación, reference PID2022-139403NB-C22). AOA is grateful to the FPU programme, funded by the Spanish Government (Ministerio de Educación, Cultura y Deporte, reference FPU17/03796). We are also grateful to Dr. Vallés-Casanova for his invaluable recommendations regarding the implementation of the code, to Dr. Provost and Dr. Artana for their insightful suggestions and guidance at the beginning of this study, and to Dr. Machín and Dr. Rintoul for their meticulous review of the initial manuscript draft. Additionally, we want to extend our gratitude to the authors of Parcels for developing the code and make it freely available. This article is a publication of the Unidad Océano y Clima of the Universidad de Las Palmas de Gran Canaria, an R+D+I CSIC-associate unit. The authors also recognize the institutional support of the Spanish Government through the Severo Ochoa Center of Excellence accreditation (CEX2019-000928-S).