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In this paper, 24 years of daily sea surface height (SSH) fields constructed by merging the measurements from two/multiple simultaneously operating altimeters are analysed to investigate mesoscale eddies. Based on efficient parallel identification and optimized tracking algorithms, we present two global daily mesoscale ocean eddy datasets (http://coadc.ouc.edu.cn/tfl/) containing over 688,000 eddy trajectories that persist for at least 4 weeks as identified in the Copernicus Marine Environment Monitoring Service (CMEMS) Two-sat/All-sat datasets over the 1993–2016 period. These long-lived eddies have an average lifetime of 72 days and an average propagation speed of 5.1 kmday−1. The properties of the identified eddy contours include the amplitude, radius, area, geostrophic current speed, eddy kinetic energy (EKE), and relative vorticity, based on which a new optimized eddy tracking method is applied. The most stable properties of the eddies are included in a set of dimensionless similarity parameters. A comparison of the eddy track outputs from the ‘Two-sat merged’ and ‘All-sat merged’ data products using our algorithm (hereafter called I4Eddy) shows that the ‘All-sat merged’ data are more suitable for studying global eddy tracks. The eddy trajectory data are also compared with two other published global eddy trajectory products, and the results demonstrate the efficiency of our method. The accuracy of our method’s eddy identification algorithm and its moderately conservative eddy tracking properties allow our algorithm to generate more continuous eddy tracks without large jumps. These elaborate datasets can be used to study the relationships between mesoscale eddies and other oceanic phenomena.
Tian et al. (2019) studied this question.