News

01.06.2021 12:33 Age: 3 yrs

New versions of the Mesoscale Eddy Trajectories Atlas product

Category: Website updates

The new versions of the Mesoscale Eddy Trajectories Atlas, META3.1exp DT allsat and twosat, provide new parameters for eddy detection and an improved tracking scheme.

The META3.1exp DT allsat (DOI : 10.24400/527896/a01-2021.001>) and twosat (DOI : 10.24400/527896/a01-2021.002) versions differ from the historical META2.0 product by 4 evolutions: 

- The eddy detection is made on Absolute Dynamic Topography maps instead of Sea Level Anomaly maps, for a better representation of mesoscale structure over Mean Dynamic Topography specific patterns 

- The filter applied on the input maps is an 2D Lanczos filter with a 700 km half-power cutoff wavelength, to better take into account the spatial scales of the Mean Dynamic Topography. The filter used in META2.0 had a 1000 km half-power cutoff wavelength. 

- The detection algorithm of META3.1exp is the Py-Eddy-Tracker, freely available on a GNU license at https://github.com/AntSimi/py-eddy-tracker, written in the Python language and associated with a large documentation (https://py-eddy-tracker.readthedocs.io/en/v3.3.1/). The main changes are the amplitude threshold (0.4 cm), the unique extremum within an eddy, and the availability of the eddy’s contours. 

- The tracking scheme is now based on the contour’s overlap, with a maximum of 4 consecutive virtual eddies. 

Each change was evaluated with a similarity coefficient, comparing individual eddies in intermediate datasets, to ensure a continuity between META2.0 and META3.1exp.