An assessment of mesoscale eddies simulated by a global eddy-resolving ocean forecast system in the South China Sea

This research evaluates the performance of an eddy-resolving forecast system (LFS) in simulating mesoscale eddies over the South China Sea (SCS) through a comparative analysis with satellite observations and the reanalysis dataset from the Global Ocean Physics Reanalysis product (CMEMS). The findings indicate that the spatial characteristics of eddy kinetic energy, number, and amplitude of coherent mesoscale eddies simulated by LFS exhibit a reasonable agreement with satellite observations. The reproduced seasonal variations are also comparable to outputs from the CMEMS reanalysis dataset. Nevertheless, certain systematic biases have also been identified. In the SCS, LFS generates approximately 17% fewer eddies than observed. Such biases are also evident in the CMEMS reanalysis dataset. Similar to the statistics shown in the CMEMS reanalysis dataset, both cyclonic and anticyclonic eddies are significantly weaker in LFS compared to the observations. Additionally, the composite three-dimensional structures of mesoscale eddies simulated by LFS exhibit a remarkable similarity to those identified in the CMEMS reanalysis datasets. This work lays the foundation for further studies using LFS to investigate the predictability of mesoscale eddies and enhance the accuracy of simulations.