Reply on EC1

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> The methods used to identify coherent ocean eddies are either Eulerian or Lagrangian in nature, and nearly all existing eddy dataset are based on the Eulerian method. In this study, millions of Lagrangian particles are advected by satellite-derived surface geostrophic velocities over the period of 1993&ndash;2019. Using the method of Lagrangian-averaged vorticity deviation (LAVD), we present a global Lagrangian eddy dataset (GLED v1.0, Liu and Abernathey, 2022, <a href="https://doi.org/10.5281/zenodo.7349753" target="_blank" rel="noopener">https://doi.org/10.5281/zenodo.7349753</a>). This open-source dataset contains not only the general features (eddy center position, equivalent radius, rotation property, etc.) of eddies with lifetimes of 30, 90, and 180 days but also the trajectories of particles trapped by coherent eddies over the lifetime. We present the statistical features of Lagrangian eddies and compare them with those of the most widely used sea surface height (SSH) eddies, focusing on generation sites, size, and propagation speed. A remarkable feature is that Lagrangian eddies is generally smaller than SSH eddies, with a radius ratio of about 0.5. Also, the estimated mass transport by Lagrangian eddies is nearly an order of magnitude smaller than that by the Eulerian calculation, indicating that the coherent contribution to the total eddy transport is very limited. Our eddy dataset provides an additional option for oceanographers to understand the interaction between coherent eddies and other physical or biochemical processes in the Earth system.