Can we monitor the Atlantic Meridional Overturning Circulation using the sea surface height?
Detta är ett förslag på examensarbete för kandidat- eller masternivå vid Institutionen för marina vetenskaper. Examensarbeten vid Institutionen för marina vetenskaper görs självständigt och bedöms individuellt.
Subject: Oceanography
Level: Bachelor’s (15hp) or Master’s (45-60 hp) thesis project
Location: Gothenburg
Supervisor: Fabien Roquet
Project background
Sea surface height (SSH) is a key dynamical property, whose gradient determines the intensity and direction of surface geostrophic currents. Since the advent of satellite altimetry in the early 90s, it has become possible to observe directly both its temporal and spatial variability with sufficient accuracy, revealing all the richness of the eddy turbulence and the complexity of major current systems. SSH provides precious information on the near-surface ocean circulation, but it can also tell a lot about the deeper ocean circulation.
Roquet et al. 2011 demonstrated there is a close match between the position of the mean SSH contour (i.e. the places where the sea level exactly equals the global mean sea level) and the zero-wind stress curl (i.e. the places where the Ekman pumping reverses) almost everywhere, a clear indication that Ekman pumping is a major driver of the global ocean circulation.
However, they found that it was not the case in the Atlantic basin, and speculated it might be related to the presence of deep ocean currents associated with the Atlantic meridional overturning circulation (AMOC; eg McCarthy et al 2021).
Project description
In this project, we want to test whether there may be a relation between the sea surface height and the AMOC, that could be used to provide a useful surface-based indicator of the AMOC strength.
We will focus on the position of zero SSH contour, and how it varies with time at both seasonal and interannual time scales. We will seek correlations between the position and zonal with the AMOC variability.
The analysis will be carried out on both observational datasets (Aviso for SSH, Rapid array for AMOC), and on model-based reanalysis products (CMEMS GLORYS025 or ECCOv4).
Skills
- Analyze complex observational datasets and extract information
- Learn about the important ocean current systems and their variability
- Learn how to analyse data with a scientific programming tool
Contact
Fabien Roquet
Professor
E-mail: fabien.roquet@gu.se
References / Links
Roquet, F., Wunsch, C., Madec, G., 2012. On the Patterns of Wind-Power Input to the Ocean Circulation. Journal of Physical Oceanography 41, 2328–2342. https://doi.org/10.1175/JPO-D-11-024.1
McCarthy, G.D., Smeed, D.A., Johns, W.E., Frajka-Williams, E., Moat, B.I., Rayner, D., Baringer, M.O., Meinen, C.S., Collins, J., Bryden, H.L., 2015. Measuring the Atlantic Meridional Overturning Circulation at 26oN. Progress in Oceanography 130, 91–111. http://dx.doi.org/10.1016/j.pocean.2014.10.006