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To study the optimal design of Wave Glider parameters in the wave environment of the Northwest Pacific Ocean, the North Indian Ocean, and the South China Sea, the average velocity of a Wave Glider was taken as the evaluation criterion. Wave reanalysis data from ERA5 were used to classify the mean wave height and period into five types by the K-means clustering method. In addition, a dynamic model was used to simulate the influence of umbilical length, airfoil, and maximum limited angle on the velocity of the Wave Glider under the five types of wave element. The force of the wings was simulated using FLUENT as the model input. The simulation results show that (1) 7 m is the most suitable umbilical length; (2) a smaller relative thickness should be selected in perfect conditions; and (3) for the first type of wave element, 15° is the best choice for the maximum limited angle, and 20° is preferred for the second, third, and fourth types, while 25° is preferred for the fifth type.

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The Kuroshio Extension Region (KER) has the most active oceanic mesoscale eddies within the North Pacific Ocean, nevertheless, there is a lack of observations on the three-dimensional (3D) fine structure of these eddies. Satellite altimeter data and underway observations were used in combination to conduct a fine-scale characterisation of the 3D thermohaline structure and circulation of a mesoscale cyclonic eddy within the KER during June, 2014. The results showed that isotherms in the six in situ sections consistently exhibited enhanced upward bending and negative temperature anomalies were distinct. At locations closer to the centre of the eddy, the negative temperature anomalies became more significant and the intensity of the cold core became more pronounced. The isohalines also trended upwards, with the upper and lower levels having negative and positive anomalies, respectively. The isohalines at the various layers similarly exhibited a clear eddy-like structure from the subsurface down to 1,000 m. Both the actual flow field measured by the Acoustic Doppler Current Profiler (ADCP) and the geostrophic flow field based on thermohaline data indicated a significant asymmetric cyclonic circulation structure. By comparing with the in situ data, the HYbrid Coordinate Ocean Model (HYCOM) is capable of depicting the mesoscale eddy while the magnitude and eddy location deviate from in situ observations.

The high-resolution observation data from June 2019, Argo data from 1997 to 2019, and the multi-observation ARMOR 3D dataset from 1993 to 2019 were used to study the three-dimensional (3D) structural characteristics of the mesoscale cyclonic eddy (CE) in the Kuroshio Extension region (KER). The observed eddy has a typical 3D structure of the KER CE, which was a longer lifespan eddy in this KER. The maximum anomalies of temperature and salinity were −7.69 °C and −0.71 PSU, which were located at the 350 m depth. In the vertical, the observed and composite eddy had a dipole structure, while ARMOR 3D had a monopole. The study of the velocity fields indicate that ARMOR 3D underestimates the velocity below 500 m. The 3D structures of the CE composite eddy of Argo were comparable to the observations, whereas the temperature and salinity anomalies were weaker than the observation. The surface of the Argo composite eddy shows a positive temperature anomaly within 50 m, which used to be opposite to the observation. This phenomenon was due to the limited Argo data of the composite eddy, and most of them were the observed profiles of winter CE in the weak years of EKE in the KER. We tried using ARMOR 3D to explore the reliability of ARMOR 3D composite eddy and compared the seasonal variations of temperature/salinity anomalies of the cyclonic and anticyclonic eddy. The anomalies of temperature and salinity caused by CE have seasonal variations: the anomalies have been strong in summer and weak in winter. This is consistent with the variant of eddy kinetic energy (EKE), but AE has no seasonal variation.