The impacts of mesoscale eddies on the modulation of typhoon-induced oceanic responses are important for understanding ocean dynamics. Satellite observations identified prominent ocean surface temperature and chlorophyll changes over the regions with mesoscale eddies after two sequential typhoons, e.g., Linfa and Nangka, in the South China Sea. The impacts of typhoons on the ocean surface were more prominent within cyclonic eddies than within anticyclonic eddies. The wind speed (translation speed) of Linfa was much larger (slower) than that of Nangka; thus, the changes induced by Linfa were stronger. However, the second typhoon easily generated mixing through the weak stratification induced by the first typhoon and impacted the upper ocean. The strong chlorophyll enhancement induced by Nangka was identified at a cyclonic eddy. Using a combination of reanalysis data, the depth of water origin (DWO) was applied to quantify the depth to which a typhoon’s impact could be exerted. Prominent changes were identified when the DWO reached the depth at which the temperature and nutrients differed from those within the mixed layer. This method can overcome the impacts of cloud coverage when examining a typhoon’s influence with remotely sensed data and offers a quantitative approach to determine the mechanisms responsible for typhoon-induced ocean surface changes.

Four moorings were deployed near “Dragon Flag,” an active hydrothermal vent in the valley of the Southwest Indian Ridge. The goal was to examine the variability of currents and temperature, which will guide the trajectory of spreading plumes. The mean current was cross‐isobath, and the circulation was characterized by a submesoscale circulation. Observed currents also showed fluctuations with periods of 1–15 days. The inferred phase speed and wavelength for the wave with a period of 4.4 day are 10.4 km d⁻¹ and 45.8km, respectively, which are consistent with the topographic Rossby wave theory. The persistent warming tendency with corresponding variation of salinity based on background θ‐S properties may be caused by background circulation and divergence of the water column. The warming or cooling episodes were most likely as signatures of isopycnal surface depression or uplifting induced by the moving of mesoscale eddies. Well‐resolved rotary spectra exhibited important nonlinear interactions between inertial and semidiurnal tide in the velocity and temperature records. Amplification of near‐inertial currents in the near bottom is also exposed. These discoveries provided new evidence for the nonlinear interaction and trapped near‐inertial waves by the ridge, which occurred in the deep ocean of the Southern Hemisphere. Such nonlinear interaction may represent a significant energy loss pathway for the internal waves, and part of the decay of such motion would likely result in increased mixing to maintain the abyssal stratification. Enhanced near‐inertial motions can play a major role for the local advection of hydrothermal plumes.

Intensification rates of tropical cyclones (TCs) are critical in determining their lifetime maximum intensity and destructive power. However, the interdecadal variability of TC intensification rates in the Western North Pacific (WNP) remains unclear. In this study, we focused on the changes in TC intensification rates during 1980-2022 and found an abrupt increase in TC intensification rates after 2002. This change was primarily attributed to TCs undergoing rapid intensification (RI-TC). Furthermore, our investigations revealed that the RI-TC intensification rates were strongly related to the proportions of intensification rates ≥10 knots/6 h (IR-10) (r = 0.88), and the frequency of IR-10 events was highly correlated to sea surface temperature anomalies (r = 0.79), modulated by El Niño-Southern Oscillation and Interdecadal Pacific Oscillation. Additionally, we found that the IR-10 occurrence frequency shows a northwestward shift during 1980–2022, and this shift was primarily driven by 500 hPa vertical velocity, followed by vertical wind shear. These findings provide crucial insights into the evolution of TC intensification rates in the WNP over the past four decades. The role of IR-10 should not be underestimated in TC development, which could serve as a crucial parameter for the TC intensity prediction.

Tropical cyclone-induced upwelling has an important influence on ocean temperature and chlorophyll-a (Chl-a) concentrations, which are modified by the existence of mesoscale eddies. This paper investigates the regional dynamics and associated variability in temperature and Chl-a during the passage of three typhoons (Kammuri, Nuri, and Hagupit) with similar tracks in the northern South China Sea (SCS) during 2008 using remote sensing and in situ observations. The measurements of wind and sea surface temperature obtained by a buoy and satellite were found to be similar, and both showed that typhoons have prominent impacts on the ocean’s upper layer. Sea surface cooling is first identified during the passage of each typhoon, particularly on the right side of typhoon tracks. Increased Chl-a concentrations were observed in the surrounding areas after the passage of typhoons Nuri and Hagupit, with large offshore blooms (Chl-a increases of 0.27–0.33 mg m⁻³) identified along the tracks of Nuri and Hagupit 3 to 4 days after their passage. Such blooms are highly dependent on the cooling associated with typhoon-induced mixing and upwelling. The pre-existing eddies modified the surface variations, and a perfect match was identified between the polarities of the eddies and the ocean surface changes. An anomalously high offshore Chl-a enhancement entrained by a cyclonic eddy occurred along the track of Nuri 4 days after its passage; in this instance, typhoon-induced upwelling was reinforced by the cyclonic eddy. In comparison, typhoon-induced upwelling is inhibited by anticyclonic eddies, resulting in much less prominent changes. The combination of typhoon winds and eddies can modify the productivity of marine phytoplankton, and a comprehensive understanding of typhoon-induced dynamics will aid in understanding ecosystem responses to typhoons.

A mooring and a real-time buoy allowed observation of oceanic and atmospheric variation in the wake of the 2008 Typhoon Hagupit in the South China Sea (SCS). In the present study, a regional ocean modeling system (ROMS) was used to explore the propagation characteristics of near-inertial waves (NIWs) along the continental shelf. The simulated NIWs were similar to the observation results. There were strong NIWs after the passage of Typhoon Hagupit, and the NIWs presented dual peaks, with one located in the mixed layer and the other at the thermocline. In the upper layer, the near-inertial kinetic energy on the left of the typhoon track was slightly weaker than that on the right. The responses of the ocean to the typhoon in shallow (200 m) areas were different. The thermocline was significantly enhanced and deepened in shallow areas. The near-inertial kinetic energy of the thermocline in shallow areas occurred earlier and more intensely than that in the deep areas. The shallower mixed layer and the stronger thermocline in shallow areas are the main reasons for the difference in response. When the typhoon arrived, the mixed layer in shallow areas sank rapidly, causing the thermodine to sink, and the thermocline strength to increase and the thickness to decrease. The thermodine triggered NIWs during its compression. High compression and a strong thermocline result in powerful NIWs.

Based on the wave reflection principle, a floating flapping-panel wave energy converter was developed. The feasibility study and optimization study of the new WEC was carried out by laboratory research and computational fluid dynamics techniques. A numerical model was developed for an in-depth study to establish the relationship between slope tilt angle and power. The results for different wave periods show that the power take-off damping coefficient has a significant effect on the power. Meanwhile, the effects of flap length and wave height on converter resonance and power are investigated. Finally, a preliminary laboratory physical model test of the device is conducted. The flapping-panel-slope structure is very feasible and effective with good hydrodynamic performance.