EGU25-11923, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-11923
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Spatial-Temporal Analysis of Remotely Sensed Coherent Mesoscale Eddies in the Southern Ocean 
Dorathy Yuan-Jane Lo1 and Miguel Ángel Morales Maqueda2
Dorathy Yuan-Jane Lo and Miguel Ángel Morales Maqueda
  • 1University of Newcastle upon Tyne, School of Natural and Environmental Sciences, Newcastle upon Tyne, United Kingdom of Great Britain – England, Scotland, Wales (y.lo2@ncl.ac.uk)
  • 2University of Newcastle upon Tyne, School of Natural and Environmental Sciences, Newcastle upon Tyne, United Kingdom of Great Britain – England, Scotland, Wales (nmm164@newcastle.ac.uk)

We investigate changes in the properties of Transient Coherent Mesoscale Eddies (TCMEs) in the Southern Ocean over the past three decades. Specifically, the study investigates whether eddy characteristics have changed in response to the strengthening and southward migration of circumpolar winds around Antarctica. Eddy data have been extracted from the Mesoscale Eddy Trajectory Atlas and AVISO altimetry from 1993 to 2019. The research area is the spherical segment between 30°S and 80°S, which includes the ACC. The eddy properties analysed are eddy number, amplitude, radius, lifetime, and eddy kinetic energy. We distinguish between the Total Eddy Kinetic Energy (TEKE), that is, the energy of all mesoscales turbulent motions and the Total Transient Coherent Mesoscale Eddy Kinetic Energy (TMKE), which is the energy contained in TCMEs. Both TEKE and TMKE increase by about 15% in the study period. TCME radius and amplitude also increase moderately by 2% and 3%, respectively, while eddy number goes down by 3%. We also study the connection between the first baroclinic Rossby Radius of Deformation (RRD), calculated from GLORYS ocean reanalysis data, and the altimetry-derived eddy radius. As expected, average TCME (RRD) radius increases from 44 km (7 km) south of the ACC, through 47 km (15 km) within the ACC, to 50 km (23 km) north of the ACC. We detect no significant trend in RRD in the Southern Ocean and so, the observed increase in TCME radius cannot be easily ascribed to changes in stratification. The eddy response to an increase in circumpolar winds in the Southern Ocean by about 3% during the last three decades has been used to explain the near insensitivity of the ACC to the changing winds via eddy saturation and eddy compensation mechanism. Our analysis, indeed, demonstrates that changes in eddy properties are commensurate, at least in relative magnitude, to coetaneous shifts in wind strength.

How to cite: Lo, D. Y.-J. and Morales Maqueda, M. Á.: Spatial-Temporal Analysis of Remotely Sensed Coherent Mesoscale Eddies in the Southern Ocean , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11923, https://doi.org/10.5194/egusphere-egu25-11923, 2025.