The Gulf Stream control of the North Atlantic carbon sink

Dr Bieito Fernández Castro, UoS, Dr Louis Clement, Prof Alberto Naveira-Garabato, Mr Carl Spingys, Dr Robyn Tuerena, SAMS

The ocean provides a crucial uptake of carbon from the atmosphere, acting to moderate the rise in atmospheric carbon dioxide (CO2) from human emissions, with a major fraction of the ocean CO2 uptake taking place in the North Atlantic. As the main ocean current in the North Atlantic, the Gulf Stream is known to play a key role in controlling regional and global climate, by redistributing heat between low and high latitudes. However, the role of ocean circulation and, in particular, the Gulf Stream, in controlling the North Atlantic carbon sink is far less certain, which critically hampers our capacity to predict the sink’s future evolution [1,2]. In this project, this key knowledge gap will be addressed by investigating the mechanisms that control the impact of the Gulf Stream on CO2 uptake locally, along the stream path, and downstream, in the subpolar North Atlantic. Specifically, you will address the question of how the vertical and lateral mixing of the warm, nutrient-rich, anthropogenic carbon-poor waters of the Gulf Stream regulates the biological and physical uptake of carbon dioxide. The project is based on the analysis of state-of-the-art physical and biogeochemical data collected with autonomous vehicles [3] along and across the Gulf Stream pathway in the North Atlantic.


The Gulf Stream transports nutrient-rich, anthropogenic carbon-poor waters across the Florida Straits into the North Atlantic and northward towards the subpolar gyre. When those waters mix with surface and adjacent waters, they impact the physical and biological processes that regulate CO2 uptake. Therefore, the mixing processes occurring along the Gulf Stream play a key role in regulating the rates and distribution of air-sea CO2 uptake. In the project, you will analyse data from a glider mission (spring-autumn 2023) along and across the Gulf Stream. The mission, in which two gliders equipped with physical sensors (including a turbulence package) and biogeochemical sensors will be deployed, is part of a NERC-funded grant (C-Streams). The glider data will serve to (i) quantify the intensity of turbulent mixing along and across the density surfaces of the Gulf Stream, (ii) identify the mechanisms that drive such mixing and (iii) assess their impact on the downstream evolution of nutrient and carbon concentrations and the uptake of CO2. The candidate could potentially use data from biogeochemical Argo floats deployed alongside the glider, and high-resolution ocean models to guide their interpretation and assess the broader-scale implications of their findings.



The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at Ocean and Earth Science. Specific training will


·         Opportunities to take part in fieldwork, which may include glider deployments

·         Training in numerical and statistical techniques with programming in Python.

·         Processing and analysis of glider data and various observational datasets.

·         Theoretical understanding of a range of ocean mixing processes.

·         Possible opportunities to take part in glider training, e.g., at a summer school

·         Opportunities to attend national/international conferences to disseminate the candidate’s results and to broaden their scientific network.

Opportunities to visit partner institutions (University of Liverpool, SAMS, University of Miami).

Eligibility & Funding Details: 

Please see for details.


Background Reading: 

[1] Ridge, S. M., & McKinley, G. A. (2020). Advective controls on the North Atlantic anthropogenic carbon sink. Global Biogeochemical Cycles, 34, e2019GB006457.

[2] Williams, R. G., et al. (2011). Nutrient streams in the North Atlantic: Advective pathways of inorganic and dissolved organic nutrients, Global Biogeochem. Cycles, 25, GB4008, doi:10.1029/2010GB003853.

[3] Dove, L. A., Thompson, A. F., Balwada, D., & Gray, A. R. (2021). Observational Evidence of Ventilation Hotspots in the Southern Ocean. Journal of Geophysical Research: Oceans, 126(7).