Most download

As a pivotal intertidal blue-carbon ecosystem, the seagrass-mangrove continuum is a focal point of contemporary blue-carbon research. In contrast to individual ecosystems, the continuum facilitates lateral carbon transport and redistribution between systems via tidal forcing—a process that profoundly influences regional and even global assessments of blue carbon budgets. However, the internal carbon cycling within the continuum and the multi-interface, multi-process coupling mechanisms of carbon sequestration remain a black box, representing one of the hot topics in blue carbon research. Here we systematically synthesize current understanding of carbon cycling in the seagrass-mangrove continuum, mapping key processes—from plant photosynthetic carbon sequestration, sediment carbon accumulation to aquatic carbon transformation, and gas exchange—within a novel, dual perspective of “vertical sequestration vs. lateral transport”. Special emphasis is placed on tide-driven lateral carbon fluxes (e.g., litter fall, DOC, POC, DIC), highlighting their central role in the continuum’s carbon dynamics. Given the complexity of intertidal habitats, future research on the coupled carbon cycling mechanisms within the seagrass-mangrove continuum remains a critical and underexplored field. In particular, key processes such as plant carbon fixation mechanisms, sediment carbon accumulation, and elemental exchange urgently require further investigation.

Deep-water sedimentary processes are key drivers that shape seafloor topography and actively participate in marine material cycles, thereby playing a crucial role in the formation of depositional systems and material cycling along continental margins and within deep-sea basins. The transport and transformation of carbon elements and carbon-containing substances are essential for sustaining organic life and maintaining climate stability. As an important end-member reservoir in this cycle, deep-sea sediments act as efficient sinks for atmospheric greenhouse gases, exerting significant regulatory effects on climate evolution over geological timescales. This study aims to elucidate the coupling mechanisms between distinctive deep-water sedimentary processes and organic carbon burial, providing a theoretical basis for establishing the “Shelf edge-slope-deep sea basin organic matter continuous transport system” and the “Deep-water organic carbon burial pyramid model”. By comprehensively analyzing representative deep-water organic carbon burial systems in global ocean basins, this research demonstrates that turbidity currents and bottom currents are the main dynamic mechanisms enabling the continuous transport of deep-water organic matter. The (micro)biological carbon pump, turbidity current carbon pump, bottom current carbon pump, and deep stratigraphic carbon pump together form the core framework for deep-water sedimentary carbon burial. Furthermore, the factors influencing deep-water organic carbon burial outcomes exhibit hierarchical characteristics. However, current research on deep-water organic carbon burial is still in its early stages, with limited case studies and mechanistic understanding, underscoring the urgent need to strengthen research on carbon burial processes in deep-water environments.

The United Nations Decade of Ocean Science for Sustainable Development (2021-2030) (hereinafter referred to as the “UN Ocean Decade”) is a global scientific initiative aimed at transforming and advancing the global ocean governance system through enhanced marine scientific research and innovation. By establishing a collaborative framework that spans disciplines, regions, and institutions, the initiative seeks to improve ocean observation capabilities, promote data and knowledge sharing, and strengthen the translation of scientific findings into policy and practice. As one of the participating countries in this initiative, China has systematically advanced related actions through the establishment of a national committee, the leadership of major scientific programs and construct Decade Collaborative Center. In this process, scientific research institutions have played a critical role in the implementation of scientific programs, technological innovation, and international cooperation. For instance, the Second Institute of Oceanography, Ministry of Natural Resources has led or deeply involved in several endorsed UN Ocean Decade actions that have established internationally recognized research and collaboration systems in areas such as conducting cutting-edge science and technology, and promoting capacity-building. Although significant progress has been made in the implementation of the UN Ocean Decade, global ocean governance still faces numerous challenges. These include disparities in technological capabilities and resource investments among countries, inadequacies in data-sharing mechanisms, and inefficiencies in translating scientific outcomes into policy. Additionally, geopolitical factors may also impact international cooperation. To achieve the goals set for 2030, further efforts are needed to deepen scientific innovation, improve open-sharing mechanisms, and strengthen inclusive collaboration, thereby promoting the establishment of a more equitable and effective global ocean governance system. In this process, research institutions worldwide can contribute to the realization of the UN Ocean Decade vision by continuing to participate in global observation networks, advancing digital and intelligent technologies, and supporting regional cooperation and capacity-building.

The sediment source-to-sink system serves as a critical link connecting active carbon pools (e.g., atmosphere, biosphere, hydrosphere) with the stable lithospheric carbon pool, playing a core buffering role in the global carbon cycle. As the core area of marine sedimentary carbon sinks, delta-shelf regions account for over 80% of the global marine sedimentary organic carbon flux while occupying less than 8% of the global ocean area. The processes and mechanisms of carbon burial in these regions are crucial for global carbon balance. This paper systematically reviews the source composition and sedimentary flux characteristics of terrestrial organic carbon in delta-shelf sedimentary systems, focuses on elaborating organic carbon source-to-sink tracing technologies, remineralization processes and their dominant mechanisms, analyzes the impacts of human activities on sedimentary carbon sinks, and discusses marine negative emission and carbon sequestration enhancement schemes based on sediment management. Studies show that the heterogeneity of terrestrial organic carbon, physicochemical conditions of the sedimentary environment, and human disturbance collectively regulate the migration, transformation, and burial efficiency of organic carbon. Currently, the potential of sedimentary carbon sinks has not been fully exploited; thus, it is urgent to promote the integration of sedimentary carbon sinks into the global climate governance system through methodological innovation, mechanism deepening, and technological development, so as to provide scientific support and feasible paths for achieving the temperature control goals of the Paris Agreement.

To investigate how tidal dynamics influence the composition of dissolved metabolites in seawater, we collected seawater samples across a semidiurnal tidal cycle, spanning both the salinity and turbidity fronts of the Changjiang River Estuary in March 2023. Using high-resolution mass spectrometry-based untargeted metabolomics, a total of 1 379 metabolite molecules were annotated (annotation rate of 6.8%), covering 14 super classes. Among these, organoheterocyclic compounds, benzenoids, lipids and lipid-like molecules were dominant (accounting for 59.1%). The results indicated that the composition of metabolites was significantly influenced by tidal forces, with greater heterogeneity during ebb tide than flood tide, revealing a temporal asynchrony between tidal movement and metabolite compositional variation. Statistical analyses further demonstrated that metabolite compositions were significantly negatively correlated with salinity, and that non-conservative nutrients (nitrate, phosphate, and silicate) exerted strong influences on metabolite variations. These results suggested that terrestrial dissolved organic matter inputs were a primary driver, with their influence further modified by brackish water mixing. In addition, the correlation between turbidity and most metabolites was relatively week. However, substantial percentage changes in lipids and lipid-like substances were observed within the suspended sediment front, indicating that the transformation of dissolved organic matter driven by resuspension processes primarily occurs under strong hydrodynamic conditions. Analysis of differential metabolite during flood and ebb phases further showed that these substances were dominated by secondary metabolites, such as lipids and heterocyclic compounds. These substances might reflect regulation by microbial community interactions. Overall, this study highlights the short-term tidal influence on dissolved organic matter composition and provides new insights into how multi-scale physical processes regulate organic matter cycling in estuarine environments.

To assess the potential impact of plumes generated by deep-sea mining on the midwater ocean, this study systematically analyzed the flow field characteristics of the intermediate currents at the 1 000 m and 2 000 m in deep-sea mining areas of the Pacific Ocean (Western Pacific: Block C, Block M, Block CW, Block WJ; Eastern Pacific: Block A5, Block KW, Block EK, Block A12678, Block A3, Block A4) and predicted the zonal movement trend of midwater plumes. The analysis was based on the global Argo float trajectory and mid-depth current dataset from the China Argo Real-Time Data Center covering the period from August 1997 to October 2024, combined with data from 3 moored observation stations. The results show that: (1)The currents at the 1 000 m layer in the Pacific mining areas are mainly controlled by zonal currents, with the velocity of eastward jets being greater than that of westward jets. The velocity and direction of currents in the mining areas are sensitive to changes in latitude. (2)The eastward jets that affect the 1 000 m flow field in the Western Pacific mining area have the center located at 14°N (weak) and 18°N (strong). Under their influence, in the southern part of the Block M, the midwater plumes move eastward. In other areas, the midwater plumes move slowly westward.(3) The eastward jets that affect the 1 000 m layer of the Eastern Pacific mining areas have the centers located at 7°N and 9°N. They are stronger in summer and autumn, and weaker in winter and spring. (4)The flow field directional characteristics in the 2 000 m area of Block M, Block A5, Block KW and Block EK are the same as those in the 1 000 m layer, indicating that the depth affected by jets can reach 2 000 m.

Spaceborne synthetic aperture radar (SAR), with its all-weather and day-and-night imaging capability, has demonstrated tremendous value in ocean monitoring. This paper provides a systematic review of the current research status of spaceborne SAR technology in the field of marine monitoring, from the perspectives of ocean dynamic environmental parameters and maritime targets. For the former, we summarize mainstream SAR-based techniques and algorithms for monitoring ocean environmental parameters such as waves, internal waves, eddies, winds, currents, and seafloor topography, and further discuss the roles of multi-frequency, multi-polarization, and multi-mode SAR data in improving inversion accuracy. For the latter, we review SAR-based methods for the detection of maritime targets including sea ice, oil spills, vessels, and offshore infrastructures, highlight the importance of multi-polarization information in characterizing target scattering properties. In addition, this paper reviews and evaluates recent advances in applying artificial intelligence to SAR-based ocean monitoring and discusses future development directions for SAR ocean remote sensing technologies.

The vertical structure of phytoplankton is key to understand the biological carbon pump in the Southern Ocean-Indian sector. This study systematically analyzed the seasonal and interannual variability in the vertical distribution of chlorophyll a （Chl a） and phytoplankton carbon biomass （C_phyto） and their environmental drivers in this region， using satellite observations， BGC-Argo floats， and reanalysis data （2015-2018）， with a focus on the 2015/2016 El Niño event. Results showed that Chl a was mainly distributed in the upper 0-100 m， with a pronounced subsurface chlorophyll maximum layer （SCML） at 10-100 m. Seasonal variability was significant： during austral summer （Dec-Feb）， sufficient light （PAR>100 μmol·m^-2·s^-1） supported peak Chl a and C_phyto in the upper 0-100 m [ρ（Chl a）>0.75 mg·m^-3， C_phyto>20 mg·m^-3）. In austral winter （Jun-Aug）， reduced light availability and a deeper mixed layer collectively led to the dissipation of the SCML and the lowest annual values of Chl a and C_phyto [ρ（Chl a）<0.5 mg·m^-3， C_phyto<10 mg·m^-3]. The deepening of the mixed layer extended the vertical distribution of Chl a to approximately 200 m， whereas the vertical structure of C_phyto showed no corresponding significant change， leading to a pronounced decoupling between Chl a and C_phyto in the 0-200 m. During the 2015/2016 El Niño， enhanced Ekman pumping shoaled the thermocline， increasing nutrient supply to the euphotic zone and intensifying and prolonging the summer phytoplankton bloom [ρ（Chl a）>1 mg·m^-3， lasting about 7 months]. This study provides scientific support for accurately assessing the Southern Ocean’s carbon sink potential and predicting the impact of extreme climate events on the phytoplankton-driven carbon pump.

Submarine cable and pipeline hold multifaceted strategic significance for national security, socio-economic development, and marine ecological environmental protection. This paper systematically reviews the evolution of China’s management policies for submarine cable and pipeline, traces the development trajectory of both the international legal framework and the domestic policy system. It analyzes the main existing issues such as administrative approval, protection management, spatial regulation, and national security. The study argues that with increasingly frequent marine development activities, lagging management mechanisms, and a complex and volatile international geopolitical landscape, submarine cable and pipeline face challenges including intensified competition for spatial resources and heightened security risks. The article proposes optimizing management policies across four dimensions: institutional restructuring, systematic protection, spatial governance, and security safeguarding. This approach aims to promote the construction of a forward-looking, efficient, and resilient governance system for submarine cable and pipeline. Such a system is essential to safeguard the implementation of China’s maritime strategy and ensure sustainable development.

Using the data of high resolution satellite sea surface temperature (SST) from January 1, 1990 to December 31, 2020, the spatial characteristics of marine heatwaves (MHWs) in the South China Sea were identified with a deep-first-search algorithm, and the characteristics of marine heatwaves at different spatial scales were further investigated. The results indicated that the small-scale marine heatwave events in the South China Sea (Type I MHWs, area<1.8×10⁴ km²) occurred the most frequently, accounting for 94.20% of the total marine heatwave occurrences. Large-scale marine heatwaves with areas exceeding 1.2×10⁵ km² (Type III MHWs) occurred only 74 times during the 31-year period, with the largest event recorded in 2015. Further analysis revealed significant differences in the spatial distribution of intensity, duration, and frequency of marine heatwaves for different spatial scales. Compared to Type I MHWs, Type II MHWs (1.8×10⁴~1.2×10⁵ km²) exhibited a noticeable increase in the average coverage area with an intensity exceeding 1.5 ℃. Statistical analysis showed that the intensity, duration, and cumulative intensity of South China Sea MHWs increased with the spatial scale of the MHWs. The intensity of Type III MHWs was 1.4 times that of Type I MHWs and 1.2 times that of Type II MHWs. In addition, the response of South China Sea MHWs areas to the El Ni?o-Southern Oscillation (ENSO) was also investigated. The results showed a significant increase in the areas of Type I to III MHWs during El Ni?o periods, with a lag of 6 to 7 months. The duration of Type III MHWs during El Ni?o was longer by 2 days compared to La Ni?a periods. This study explored the fundamental characteristics of South China Sea MHWs areas and further analyzed the commonalities and differences of MHWs at different spatial scales, providing new insights into the characteristics and mechanisms of the formation and dissipation of South China Sea MHWs.

The continental shelf regime under the United Nations Convention on the Law of the Sea (UNCLOS) marked the first time that the scope of coastal states’ sovereignty rights was extended to the deep-sea areas beyond 200 nautical miles. This provision not only endows coastal states with legal standing for the exploitation of deep-sea resources, but also fosters an institutional linkage between geoscience and international law. To date, a total of 109 submissions have been formally lodged with the Commission on the Limits of the Continental Shelf (CLCS), signifying that global continental shelf delineation has entered a new phase characterized by the high integration of scientific practice and legal procedures. Nevertheless, driven by the rapid advancement of science and technology and the sensitive impacts of geopolitics, continental shelf delineation is confronted with unprecedented challenges, which will exert a major influence on global ocean governance. Based on the 109 submissions received and 44 recommendations issued by the CLCS, this paper systematically sorts out the major progress and challenges in the delineation of continental shelves beyond 200 nautical miles from three dimensions: legal regimes, geoscientific theories, and practices. It aims to reveal how continental shelf delineation has evolved into a crucial driving force reshaping the global marine spatial order within the international deep-sea governance system where scientific evidence and legal institutions intersect, and further looks ahead to the development direction of continental shelf delineation in the context of scientific and technological progress, international cooperation, and global ocean governance.

Oyster reefs are one of the important coastal habitats. Over the past century, oyster reefs have been severely degraded worldwide. However, with the gradual recognition of the irreplaceable ecosystem service functions of oyster reefs, the significance of oyster reef conservation and restoration has become prominent in the global efforts to restore and protect degraded coastal ecosystems. This study systematically collects and collates the distribution information of natural oyster reefs and artificially restored oyster reefs in China, summarizes the main work and achievements in the field of oyster reef conservation and restoration in China since the beginning of this century. Combined with the author’s practical experience in the Wenzhou coastal zone protection and restoration project (oyster reef), the technical process of restoration is described in detail, with emphasis on the design and structure of the inclined support composite oyster reef and the artificial seedling attachment technology used in the restoration project. Corresponding suggestions are put forward, which can provide references for future oyster reef conservation and restoration work.

Using eddy-resolving numerical simulation data and historical hydrological observation data, this study investigates the sources, seasonal and interannual variability of two subsurface undercurrents under the Indonesian Throughflow—the Ombai Undercurrent located in the Ombai Strait and the Timor Undercurrent located in the Timor Channel. The results indicate that these two undercurrents exist at depths of approximately 200-800 m, which are a quasi-permanent undercurrent system. The formation of the Ombai Undercurrent is mainly related to the eastward extension of the South Java Undercurrent, while the water source of the Timor Undercurrent is more complex, mostly a mixture of the South Java Undercurrent and the Leeuwin Undercurrent. Both subsurface undercurrents exhibit significant seasonal and interannual variations, with a significant semiannual period at the seasonal scale, typically peaking during the Indian Ocean monsoon transition period (April, May, and October). Combining historical wind, satellite altimeters, and temperature and salinity observation data, it is found that the meridional pressure gradient in the subsurface layer related to local wind and their upwelling is the dominant factor leading to their seasonal changes. At the interannual scale, there is a period of 2-4 years for subsurface undercurrents, which is significantly correlated with the Indian Ocean dipole.

The estuarine turbidity maximum (ETM) is a critical hub for the transport of particulate organic carbon (POC) from estuaries to ocean. To investigate the provenance and transport patterns of POC within the ETM, the Jiulong River ETM was selected as a research site. Hourly-resolved hydrological parameters, horizontally transported POC (collected via filtration), and vertically settling POC (collected using sediment traps) were systematically sampled. POC was analyzed for organic carbon isotopes, and the Monte Carlo end-member model was employed to analyze the relative contribution of different endmembers. Then the empirical orthogonal function (EOF) analysis was applied to examine and discuss the transport patterns and their driving mechanisms of POC within the ETM. The results revealed significant spatiotemporal variations in POC sources: surface POC was primarily of riverine sources (35.5%), while bottom POC was dominated by sedimentary sources (35.1%). Settling POC was also mainly derived from sedimentary sources, reaching up to 65% in high-flow flood tide periods. The bottom POC mass concentrations (0.8-8.4 mg·L^-1) showed a significant positive correlation with the magnitude of bottom tidal current velocity (absolute range: 0-0.5 m·s^-1). The peak settling flux of particles (227.1 mg·cm^-2·h^-1) occurred during low-flow periods (profile-averaged velocity <0.2 m·s^-1). Based on the results, it is find that tidal current velocity is a key factor regulating the sources and transport of POC within the Jiulong River Estuary’s ETM. It influences the horizontal transport, resuspension, and vertical mixing processes of POC through its magnitude, direction, and duration, thereby governing the provenance composition and mass concentration of POC. This control manifests specifically in three ways: a significant positive correlation exists between tidal current velocity and POC mass concentration, where high-velocity currents primarily drive the resuspension of sediments, making this process the main source of sedimentary POC; the alternating flow patterns of flood and ebb tides are the dominant control for the shifting predominance between river and marine POC; and velocity stratification (especially during the ebb tide stage) governs the vertical mixing intensity of POC from different sources. Moreover, from the perspective of how tidal current velocity regulates POC sources and transport processes within the ETM, this study summarizes the POC transport models for different tidal stages: During the flood tide, currents drive the input of marine POC. However, the high flow velocities cause significant sediment resuspension, resulting in the overall dominance of sedimentary POC. During the high slack tide, characterized by low flow velocities, particle settlement predominates, and sediment resuspension diminishes. This leads to a relative increase in the proportions of river or marine POC. Although the contribution of sedimentary POC decreases, it remains the dominant source overall. During the ebb tide, the outgoing currents facilitate the input of river POC. Meanwhile, the high flow velocities in the surface layer have a limited effect on adding sedimentary POC. The proportional distribution among the three POC sources is closely linked to the duration of the preceding high-velocity flood tide; generally, a longer duration leads to more pronounced dominance of sedimentary POC. During the low slack tide, which also features low flow velocities, settlement is again the primary process. The contributions of the three POC sources are generally comparable during this stage. These findings provide a valuable reference for a deeper understanding of the source-to-sink processes of POC within the ETM.

This study was conducted to explore the contribution of silicon dissolution from beach sediments to the dissolved silicon budget in the coastal waters. From March to September in 2017, six field surveying cruises were conducted in the Muping offshore area (Yantai, China), the southern North Yellow Sea. By investigating monthly distributions and the averaged values of dissolved inorganic nutrients, monthly accumulation of dissolved silicate anomaly (ΔSi, as defined with the difference between dissolved inorganic nitrogen and silicate concentrations)of 1.5 μmol·L^-1 was observed in this offshore area with weak circulation from May to August. Further combining laboratory incubation experiments, theoretical calculation and field data analyses, It was found that the permeable particles in beaches could be dissolved, leaching active silicate to seawater, and increasing the offshore silicate concentration by 0.7~2.0 μmol·L^-1 every month, roughly consistent with the monthly accumulation rate of field ΔSi. Extrapolating the beach silicate-leaching flux to the length of the coastline rounding the Yellow Sea, the previously reported imbalance in silicate budget in this coastal sea could roughly be bridged. This study indicated again that the dissolving of permeable particles might contribute significantly to coastal silicate budget.

The new seawall ecological armour block is a type of face protection structure with both excellent wave dissipation performance and ecological function. In order to systematically evaluate its wave dissipation performance, this study carried out a two-dimensional wave flume physical modeling test using Zhoujiayuanshan Island in Zhoushan as the engineering background. The test systematically investigated the effects of wave period, wave height, relative water depth, wave steepness, breaking parameter, and block geometry (outer diameter and height), as well as model materials on the reflection coefficients under the action of regular waves. The results show that: firstly, the feasibility of using polypropylene random copolymer (PP-R) instead of foamed concrete in the physical modeling test is verified through the comparison experiments of nine working conditions, and the average difference in their reflection coefficient is only 1.17%. Secondly, for its wave dissipation performance, the reflection coefficient increases with increasing wave period, relative water depth and breaking parameter, and decreases with increasing wave height and wave steepness. Among all the tested conditions, the two types of blocks with outer diameter 7.5 cm-height 10 cm and outer diameter 10 cm-height 6.5 cm have the best wave dissipation performance, with average reflection coefficients of 0.395 and 0.382, respectively. Finally, the reflection coefficient formula for the six types of blocks is fitted based on the experimental data in this study. The formula has a root mean square error (RMSE) of 0.106 9, which is of high accuracy and our study can provide a certain reference for related engineering design.

The occurrence of a “triple-dip” La Ni?a event is historically rare, yet it has exerted profound impacts on global weather and climate systems. To enhance the understanding of the causes of multiple La Ni?a events and improve the prediction capabilities for weather and climate, a comparative analysis of the ocean-atmosphere processes in the tropical Pacific during the 2020-2023 “triple-dip” La Ni?a period was conducted based on multiple sets of observational and reanalysis data, employing composite analysis and other methods. Results showed that: The peak of the 2020 La Ni?a event occurred in winter and lasted the longest among this “triple-dip” La Ni?a events; the peak of the 2021 La Ni?a event also occurred in winter, with the cold anomaly centered near the eastern Pacific, classified as an “Eastern Pacific” type; the peak of the 2022 La Ni?a event occurred in autumn, relatively weaker in intensity and the shortest in duration, with the cold anomaly centered in the central Pacific, classified as a “Central Pacific” type. Further research revealed a coupling relationship between zonal wind and sea surface temperature (SST) variations. However, during this “triple-dip” La Ni?a period, the intensity and location of the eastward wind anomalies showed little variation across different La Ni?a events. In contrast, subsurface SST changes align with changes in SST anomaly centers, it may be a crucial factor influencing the intensity and type differences among this “triple-dip” La Ni?a events. Although eastward-propagating Kelvin waves had a certain impact on the ocean system, but their propagation speeds and intensities exhibited minimal variations during this “triple-dip” La Ni?a events. Additionally, the study found that variations in the growth rate of warm water volume contributed to the differences in La Ni?a intensities, while the meridional convergence and divergence of warm water led to the seasonal phase-locking phenomenon of La Ni?a events.

Using the measured data of extreme waves causing by 6 typhoons and 2 cold waves (caused by typhoon is called typhoon wave, caused by cold wave is called cold wave)during a one-year wave observation process in the Cangnan sea area of Zhejiang Province, the distribution and variation characteristics of wave parameters for each extreme wave as well as the typical characteristics of typhoon waves during Typhoon “Lekima” and “Mitag” were analyzed. The results show that the typhoon waves in the study sea area were significantly affected by the typhoon track and intensity, the stronger the typhoon intensity and the closer its proximity to the study area, the more significant and intense the process of typhoon waves, the higher the wave height and spectral peak density of typhoon waves. Both summer and autumn could be affected by extreme typhoons and lead to extreme typhoon waves. Extreme waves caused by cold wave occured both in winter and spring, of which intensity were directly affected by the intensity of cold waves, overall, extreme waves caused by cold wave were not as severe as typhoon waves. The duration of the impact of typhoon waves was two to three days, and the duration of the impact of extreme waves caused by cold wave was about 1 day; the maximum wave height and spectral peak density during extreme waves exhibited a synchronous development process of initially increasing and then decreasing. During the impact of Typhoon “Lekima”, the maximum wave height in the studied sea area was 10.80 m, with a maximum spectral peak density of 55.10 m²/Hz, the development and change process of wave spectrum was bimodal spectrum-unimodal spectrum-bimodal spectrum, and the development and change process of wave types was mixed waves dominated by swell-wind wave-mixed waves dominated by wind wave. During the impact of Typhoon “Mitag”, the maximum wave height in the studied sea area was 8.89 m, with a maximum spectral peak density of 36.37 m²/Hz, the wave spectrum was mainly composed of unimodal spectrum, with occasional bimodal spectrum. The wave type was mainly swell, with occasional mixed waves dominated by swell.