Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months. They are a key dynamic process influencing the distribution of oceanic energy, affecting energy budgets, heat distributions, and material transport. Advances in satellite remote sensing and in situ observation over the past half-century have substantially enhanced our understanding of the statistical properties, energetics, and dynamic mechanisms of mesoscale eddies, establishing this field as a major focus in physical oceanography. This article presents a comprehensive review of recent advancements in 6 key areas of mesoscale eddy research: (a) eddy detection methods and data products (leading automated detection methods and the corresponding eddy datasets and data products currently available), (b) eddy generation and dissipation (eddy generation, development, and dissipation mechanisms), (c) energy cascades (energy cascades between eddies, large-scale circulation and submesoscale processes, the role of these processes in modulating the energy transfer of near-inertial internal and surface waves, and research progress in related parameterization), (d) air–sea interaction (eddy-induced interactions, especially the interaction between eddies and typhoons), (e) interdisciplinary studies (impacts of eddies on biogeochemistry, acoustics, and other related fields), and (f) observation studies (programs dedicated to studying mesoscale eddies through in situ observation). This article also discusses research prospects on mesoscale eddies.

Satellite observational data and a regional ocean model are used to understand the evolution of Ningaloo Niño (NN) anomalies near Western Australian coast. In observation and high‐resolution (~3 km) simulations, coastally trapped positive sea level anomalies (SLAs), originated largely from the Indonesian Throughflow, are transmitted westward by mesoscale eddies. Few eddies propagate long distances offshore due to dissipation, and as a result NN signatures are predominantly confined near the coast. In coarse‐resolution (~100 km) simulations that cannot resolve eddies, oceanic anomalies propagate swiftly as long Rossby waves with much weaker dissipation and more anomalies spread to the ocean interior. Eddy‐enhanced surface warming promotes surface latent heat release and mesoscale air‐sea interactions, which acts to damp NN surface warming. These processes are not resolved by coarse‐resolution models. This study highlights the importance of resolving mesoscale oceanic processes in the simulation and prediction of NN.

The present numerical study is directed towards buoyancy driven laminar flow in a two-dimensional square enclosure with differential heating at the vertical walls. The top and bottom walls are insulated. A time-dependent sinusoidally varying perturbation is imposed at the hot vertical wall while the cold wall is maintained at a constant temperature. The results for a Prandtl number of 0.72 indicate that for perturbation amplitudes sufficiently small the heat transfer and flow field oscillations are directly proportional to the perturbation amplitude. In this linear regime, the oscillatory response behavior in the enclosure for the complete ranges of small, large and intermediate Rayleigh number and frequencies are determined and physically discussed. For larger amplitudes the response also becomes amplitude dependent, and exhibits a nonlinear behavior. The critical amplitude of the imposed oscillations for the onset of nonlinearity is found to be a strong function of the Rayleigh number.