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Seminar talk: A Lagrangian perspective on ocean ventilation in the high-latitude North Atlantic

Helen Johnson from University of Oxford is currently on sabbatical at GFI. She will give a seminar talk on May 4.


Short biography:

Portrett av Helen Johnson
Helen Johnson

I am an Associate Professor in the Earth Sciences Department at the University of Oxford. My research focuses on understanding ocean circulation and the role it plays in climate. I am particularly interested in the dynamics of the Atlantic and Arctic Oceans, and their interactions with each other and with the atmosphere. I have been a frequent visitor to Bergen over the last decade as a member of the ResClim/CHESS international evaluation board and a former adjunct professor at GFI.


A substantial fraction of the deep ocean is ventilated in the high latitude North Atlantic. As a result, the region plays a crucial role in global biogeochemical cycles and transient climate change through the uptake of carbon dioxide, oxygen, and heat. However, owing to the Lagrangian nature of the process, many aspects of deep Atlantic Ocean ventilation and its representation in climate simulations remain obscure. We investigate the nature of ventilation in the high latitude North Atlantic in an eddy-permitting numerical ocean circulation model using a comprehensive set of Lagrangian trajectory experiments. Backwards-in-time trajectories from a model-defined ‘North Atlantic Deep Water’ (NADW) reveal the times and locations of subduction from the surface mixed layer at high temporal and spatial resolution. While subduction directly into the Labrador Sea boundary current dominates NADW ventilation, processes in the open ocean set the variability, with notable impacts on the subsurface density distribution and export pathways.


Arranged date for the seminar talk: May 04, 2020 at 14:15

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