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Distribution, movement and generation mechanism of the mesoscale eddy around the Kuroshio in the East China Sea
LI Zhichao, GUO Junru, SONG Jun, BAI Zhipeng, FU Yanzhao, CAI Yu, WANG Xifeng
Journal of Marine Sciences    2022, 40 (4): 1-10.   DOI: 10.3969j.issn.1001-909X.2022.04.001
Abstract628)      PDF (3317KB)(733)      
In order to explore the distribution, formation mechanism and motion law of eddy around Kuroshio in East China Sea, firstly, the eddy distribution around the Kuroshio in the East China Sea during the past 27 years was analyzed by using the mesoscale eddy data set of the AVISO(Archiving, Validation and Interpretation of Satellite Oceanographic Data). The results show that there are 650 eddies generated in the meander of the Kuroshio, and 271 eddies in the middle part of the Kuroshio. The diameters of the most these eddies were between 100 to 150 km, and the amplitudes were between 2 to 6 cm. Secondly, the motion path and eddy motion process of the Kuroshio in the East China Sea are also analyzed. The results show these the cyclonic eddies are easy to be generated in the inner side of the Kuroshio cyclonic bend, with a long path. For example, at the cyclone bend of the Kuroshio axis in the northeast of Taiwan, the average length of the path was 87.6 km. Otherwise, when these anticyclonic eddies are generated, these eddies usually are wandered. In the middle part of the Kuroshio, the eddy showed the polar symmetric distribution characteristics of these cyclonic eddies in the west side of the Kuroshio main axis and these anticyclonic eddies in the east side of the Kuroshio main axis. Both types of eddies moved northeastward along the Kuroshio main axis. Finally, combined with reanalysis data sets of ocean current and sea surface height, the eddy motion law and generation mechanism were discussed. It is concluded that these eddies generation at the curve of the Kuroshio are related to the separation of the boundary layer of the Kuroshio fluid. The Kuroshio countercurrent from the south of Yanmei Island to the west of Okinawa Island played a key role in the polar symmetric distribution of these eddies in the middle part of the Kuroshio. These eddies usually experience three stages of growth, maturation and decay in the process of movement.
Progress of marine sand resource exploration around Hainan Island and suggestions for selection of exploration areas
TONG Changliang, SONG Jiawei, DENG Kaizhang, HAN Xiaohui, WANG Aijun, WANG Yaping
Journal of Marine Sciences    2022, 40 (3): 33-48.   DOI: 10.3969-j.issn.1001-909X.2022.03.004
Abstract403)      PDF (4123KB)(667)      
Marine sands are important submarine mineral resources. The marine sand resources of Hainan Island are widely distributed in coastal zones and continental shelf areas, with large scale, good quality and rich in heavy minerals. The basic distribution characteristics of marine sand resources around Hainan Island are described, and the progress and main achievements of marine sand exploration around Hainan Island are reviewed with emphasis on heavy mineral sand and aggregate sand. Through the exploration, 15 abnormal areas of heavy mineral placer have been delineated in the sea area around Hainan Island, and one large zirconiumtitanium placer deposit has been proved. However, due to the low level of investigation and research, the resource potential of heavy mineral placer is not clear. The scale of sediment survey around Hainan Island has basically reached 1∶250 000, which provides a solid foundation for the exploration of aggregate sand resources. In recent years, billions of cubic meters of aggregate sand resources have been discovered in the east entrance of Qiongzhou Strait and tidal sand ridge area of the western Hainan, and the resource potential is predicted to reach tens of billions of cubic meters. According to the comprehensive analysis, 8 potential exploration areas of marine sand resources can be delineated around Hainan Island. Except the east mouth of Qiongzhou Strait and the tidal sand ridge area of the western Hainan, the northeast continental shelf of Hainan, the southwest continental shelf of Hainan and Beibu Gulf area are all favorable enrichment areas of marine sand resources, and may contain heavy mineral resources potential. According to the specific sedimentary environment, the exploration objectives and tasks of each prospective area are discussed respectively. Combined with the current work progress and existing problems, the suggestions for the future marine sand exploration are put forward.

Prospect of artificial intelligence in oceanography
DONG Changming, WANG Ziyun, XIE Huarong, XU Guangjun, HAN Guoqing, ZHOU Shuyi, XIE Wenhong, SHEN Xiangyu, HAN Lei
Journal of Marine Sciences    2024, 42 (3): 2-27.   DOI: 10.3969/j.issn.1001-909X.2024.03.001
Abstract295)   HTML27)    PDF (4260KB)(317)      

Artificial intelligence in oceanography has demonstrated a great potential with the explosive growth of ocean observation data and numerical model products. This article first reviews the history of ocean big data development, and then introduces in detail the current status of artificial intelligence in oceanography applications including identifying ocean phenomenon, forecasting ocean variables and phenomenon, estimating dynamic parameters, correcting forecast errors, and solving dynamic equations. Specifically, this article elaborates the research on the intelligent identification of ocean eddies, internal waves and sea ice, the intelligent prediction of sea surface temperatures, El Ni?o-Southern Oscillation, storm surges, waves and currents, the intelligent estimation of ocean turbulence parameterization for numerical models, and the intelligent correction of waves and current forecast errors. In addition, it discusses the recent progress of applying physical mechanism fusion and Fourier neural operator for solving ocean dynamic equations. This article is based on the current status of artificial intelligence in oceanography and aims to provide a comprehensive demonstration of the advantages and potential of applying artificial intelligence methods in the field of oceanography. With the two emerging research hotspots: digital twin oceans and artificial intelligence large models, the future development direction of artificial intelligence provides enlightenment and reference for interested scientists and researchers.

Spatio-temporal evolution and driving factors analysis of the coastline in Nan’ao Island from 1976 to 2021
NING Zihao, JIANG Changbo, LONG Yuannan, WU Zhiyuan, MA Yuan
Journal of Marine Sciences    2023, 41 (2): 71-82.   DOI: 10.3969/j.issn.1001-909X.2023.02.006
Abstract226)   HTML17)    PDF (3287KB)(559)      

Coastline is one of the important geographical elements to describe the boundary between land and sea. Under the dual influence of natural factors and socio-economic factors, coastline dynamic evolution of different intensities continues to occur. Based on Landsat series satellite remote sensing images, the spatial and temporal evolution of the coastline of Nan’ao Island from 1976 to 2021 was analyzed by RS and GIS technology combined with field investigation, and the driving factors were analyzed by grey correlation analysis. The results show that : (1)In the past 45 years, the coastline of Nan’ao Island has changed significantly. The coastline length has increased by 11.06 km, and the fractal dimension have generally increased.(2)During the study period, the type of coastline changed from natural coastline dominated by bedrock to artificial coastline, the comprehensive index of coastline utilization show an increasing trend, and the main structure of coastline development and utilization show a form of single to multiple.(3)The evolution of the coastline of Nan’ao Island has obvious regional differences. That of Houzhai Town is greatly affected by human factors, and its evolution is more significant. The coastlines of Yun’ao and Shen’ao Towns are mainly affected by natural factors, and their evolutions are relatively slow.(4)Typhoon(natural disasters) and population are the main driving factors of the coastline evolution of Nan’ao Island.

Morphology, distribution and evolution process of submarine canyons in the Asian Continental Margin
WANG Yanbing, HAN Xibin, HU Zhilong, ZHAO Ning, YANG Fanlin, GE Qian, XU Dong, GAO Jinyao
Journal of Marine Sciences    2020, 38 (4): 48-57.   DOI: 10.3969/j.issn.1001-909X.2020.04.005
Abstract365)      PDF (4246KB)(581)      
Based on the SRTM15_Plus depth data, the submarine canyons in the Asian Continental Margin were identified by using the method of combining topographic surface flow analysis with contour geometry analysis. And the morphology, distribution characteristics and evolution process of the canyons in the study area were analyzed. A total of 531 submarine canyons are identified and divided into linear, meandering and dendritic according to the plane shape. The numbers of each type of canyon are 239, 75 and 217 respectively. Linear canyons are mainly distributed in the Bering Sea Basin, the Kuril Basin and the South China Sea. Meandering canyons are mainly distributed in the subduction zone east of the Bay of Bengal. Dendritic canyons are mainly distributed in the junction of the Japan Trench, the Izu Bonin Trench and the Nankai Trough, the South China Sea and the Sumatra subduction zone. According to the distribution of the canyons and the tectonic background in the study area, the morphological evolution process of “Linear-Meandering” was discussed. According to the morphological information of the main valley of dendritic canyons, it is inferred that there are “Linear-Dendritic” and “Meandering-Dendritic” morphological evolution processes.
Progress and challenges of artificial intelligence wave forecasting
LU Yuting, GUO Wenkang, DING Jun, WANG Linfeng, LI Xiaohui, WANG Jiuke
Journal of Marine Sciences    2024, 42 (3): 28-37.   DOI: 10.3969/j.issn.1001-909X.2024.03.002
Abstract137)   HTML14)    PDF (1059KB)(199)      

Waves are one of the most important phenomena in the ocean. The accurate and quick updated wave forecasting is of crucial significance for ensuring marine activities safety. The development of wave forecast is presented, including the traditional statistical wave forecasting methods, numerical wave prediction models, and the rapidly developing artificial intelligence (AI) wave forecasting methods. Currently, AI wave forecast models have been demonstrated unique advantages in terms of computational efficiency and adaptive forecasting accuracy, and they are gradually being applied in practical wave forecasting operations, transitioning from the research stage. However, they also have limitations, including limited forecasting elements, underestimation of extreme wave conditions, and weak forecasting generalization ability. Based on the characteristics of AI wave prediction, key scientific and technological issues that need to be addressed in current AI wave forecasting are proposed. These include efficient utilization of observational data, incorporation of prior physical knowledge, and enhancement of AI model safety and generalization ability.

Climatic and environmental changes over the last 1 000 years as recorded by the sediments in Beibu Gulf
LIN Junchuan, KONG Deming, CHEN Fajin, HUANG Chao,
Journal of Marine Sciences    2022, 40 (3): 49-61.   DOI: 10.3969-j.issn.1001-909X.2022.03.005
Abstract290)      PDF (3250KB)(635)      
Climate reconstructions for the last millennium are essential for understanding climate change and will provide an important basis for predicting future climate change. However, there are spatial differences in monsoonal precipitation, and the hydrothermal configurations of two important characteristic periods of the past millennium, the Medieval Warm Period and the Little Ice Age, are highly controversial, especially in southern China. Therefore, the Core BBG-02 taken from the northeastern Beibu Gulf were analyzed for chronology, grain size, major elements and trace elements to understand the physical source of the Core BBG-02 and the climate and environmental changes in its source area. The analysis of chondrite-normalized distribution patterns of rare earth element and geochemical indicators reveal that the Red River may be the main source of the Core BBG-02, and the changes in geochemical indicators of the core reflect changes in the intensity of Indian Summer Monsoon. The results indicate that the climate was warm and humid during the Medieval Warm Period and cold and arid during the Little Ice Age, which is consistent with the results of previous studies on the variation of Indian Summer Monsoon and precipitation. The variation of solar radiation intensity is the essential reason of the variation of Indian Summer Monsoon, which is also influenced by ENSO activity and Indian Ocean Dipole.

Wave characteristics and their influencing factors on Nanhui tidal flats in the Changjiang Estuary
CUI Minghui, TU Junbiao, MENG Lingpeng, GUO Xingjie, SU Ni, FAN Daidu
Journal of Marine Sciences    2023, 41 (2): 28-44.   DOI: 10.3969/j.issn.1001-909X.2023.02.003
Abstract213)   HTML15)    PDF (6284KB)(408)      

Wave is an important factor to shape the dynamic geomorphology of the open tidal flat, but researches on tidal-flat wave characteristics are still limited. Taking Nanhui tidal flats in the Changjiang Estuary as an example, the wave characteristic parameters and wave spectrum parameters were obtained by inverting flow-velocity and water-pressure data from the Acoustic Doppler Velocimeters (ADVs) at some fixed platforms, and their changes over tidal cycles and associated influence mechanisms were discussed. The results show that both normal wave direction and prominent wave direction at three stations of Nanhui tidal flats are mainly southeast during the observation period, with long-period swells dominating. The effective wave height of the three stations is positively correlated with the water depth, but the fitting coefficients of each station are different over flood and ebb periods. Wave orbital velocities are obviously modulated by the shallow water effect and the flow directions, and their maximum values usually occur at the early flooding stage, while minimum values can be observed to occur during the current transition periods. The wave energy spectrum during ebb tides is featured by the bimodal pattern because of high influence by tidal levels and coastal topography, and the peak energy is continuously attenuated and gradually dispersed with the concurrent shift of peak frequencies.

A review of the carbon cycle in river-estuary-coastal ocean continuum
CHEN Jianfang, ZHAI Weidong, WANG Bin, LI Dewang, XIONG Tianqi, JIN Haiyan, LI Hongliang, LIU Qinyu, MIAO Yanyi,
Journal of Marine Sciences    2021, 39 (4): 11-21.   DOI: 10.3969/j.issn.1001-909X.2021.04.002
Abstract1428)      PDF (2040KB)(1022)      
The river-estuary-coastal ocean continuum (referred to as the continuum hereinafter) is a transition zone connecting lands and oceans. The carbon budgets in the continuum are dynamic and uncertain components in global carbon budgets. This complex landocean interactive ecosystem can absorb atmospheric CO2 through photosynthesis and dissolution of CO2. Also, the carbon fixed by photosynthesis or chemical weathering in land and watershed can be transported horizontally to the shelf waters and open oceans. In this paper, the progress of carbon cycles in the continuum is reviewed by taking the famous Chesapeake Bay and Changjiang Estuary-East China Sea continuum as typical examples. It is concluded that systematic observation characterized with land-sea coordination, sea-space integration, point-line combination, should be combined with physicalecological numerical simulation to reveal the multiple time-space scale processes. The strategy is generally operable, and the historical retrospective of results is also achievable. Thus, it can be used to clarify the evolution of carbon exchange along the river-estuary-coastal ocean continuum and their influences on carbon budgets under the combined pressures of climate change and anthropogenic activities.


Spatio-temporal variation of suspended sediment and its dynamic factors in Liaohe Estuary
ZHAO Xuekai, GUO Kaiyuan, ZHOU Yunhao, JIA Liyuan, YANG Zhibo, ZHANG Qinxu, ZHANG Mingliang
Journal of Marine Sciences    2024, 42 (1): 36-46.   DOI: 10.3969/j.issn.1001-909X.2024.01.004
Abstract96)   HTML415)    PDF (13102KB)(231)      

Based on the L2B sediment data of HY-1C CZI from 2019 to 2020 and the meteorological and hydrological data of the same period, spatial analysis and statistical methods were applied to analyze the spatio-temporal variation characteristics and dynamic factors of suspended sediment mass concentration in the sea area of Liaohe Estuary. The results show that tide is the dominant factor in the diurnal variation of suspended sediment, and the average suspended sediment mass concentration at ebb period is higher than that at flood period. The influence of runoff on suspended sediment mass concentration in the Liaohe Estuary is mainly in the shore area, and generally does not exceed 5 m isobath. When the flow direction of ebb current is opposite to the wind direction, the turbidity zone expands horizontally in the estuary, while when the flow direction of ebb current is the same as the wind direction, the turbidity zone contracts at the top of the estuary. There is a significant correlation between wind speed and suspended sediment mass concentration, and the closer to the offshore, the stronger the effect of wind on suspended sediment. Under the influence of tidal currents, runoff and wind waves, the inner part of the 8 m contour usually develops into the maximum turbidity zone.

Remote sensing monitoring and spatial-temporal change analysis of aquaculture ponds in coastal area of Hainan Island
YUAN Xin, ZHANG Li, SONG Xixi, GU Yu
Journal of Marine Sciences    2020, 38 (1): 59-67.   DOI: 10.3969/j.issn.1001-909X.2020.01.007
Abstract199)      PDF (3141KB)(340)      
The object-oriented classification method was utilized to interpret 4 time-series Landsat data of 1990,2000,2010 and 2015 to identify the aquaculture ponds in coastal area of Hainan Island. Based on the landscape indexes and centroid migrate model,the temporal and spatial characteristics of aquaculture ponds and its impact on the coastal ecological environment were explored. The results showed that the area of aquaculture ponds of Hainan Island continued to grow from 1990 to 2015 and the regional differences were obvious. The distribution position of aquaculture area moved to the northeast of Hainan Island and the landscape indexes showed that the landscape pattern of the aquaculture area tended to be fragmention. The expansion of aquaculture ponds invaded natural wetlands such as mangroves, causing damage to the coastal ecological environment. Therefore, reasonable planning and scientific upgrading are needed for the sustainable development of aquaculture.
Assessment of tidal current energy resources in the significant waterways of Zhoushan sea area
CHEN Chao, BAO Min, YE Qin, YAN Yuhan, CAO Zhenyi, ZHANG Qianjiang
Journal of Marine Sciences    2023, 41 (3): 34-42.   DOI: 10.3969/j.issn.1001-909X.2023.03.004
Abstract252)   HTML19)    PDF (2578KB)(401)      

Tidal current energy is the kinetic energy carried in the horizontal movement of tidal water, which has great development prospects. Accurate simulation and characterization of regional tidal currents can help to efficiently evaluate the spatial and temporal distribution of tidal energy resources, which is the key to the development and utilization of tidal current energy resources. In this paper, a high-resolution numerical model of tidal currents is constructed by applying FVCOM ocean model in Zhoushan sea area where has rich tidal current energy, and the reliability of the model is confirmed by tidal level and current verification. According to the simulation results, six waterways with dense tidal current energy resources in the Zhoushan sea area were identified, among which the average energy density of Xihoumen waterway, Cezi waterway and Taohuagang waterway exceeds 2.0 kW/m2, and the maximum energy density exceeds 20 kW/m2, and the flow speed over 1.0 m/s of the whole month is more than 80%. During tidal current ebb and flow, the reflow is dominant, while the asymmetry and rotation of tidal current are low. The flow stability coefficient is more than 0.98, so it is more suitable for the development and utilization of tidal current energy than other three waterways. The best location for tidal current energy development in these three waterways was then determined by calculating the significant hours and available hours, and the corresponding exploitable tidal current energy resources were evaluated using the Farm method, which were 27.53 MW, 39.96 MW, and 130.26 MW, respectively.

Analysis of erosion and deposition evolution of inshore shoals and channels along the Jinshanzui to Longquangang segment in the northern Hangzhou Bay
FENG Lingxuan, JI Yongxing, ZHANG Xinyao, DAI Zhijun
Journal of Marine Sciences    2020, 38 (3): 92-98.   DOI: 10.3969/j.issn.1001-909X.2020.03.010
Abstract308)      PDF (4388KB)(393)      
Taking Jinshanzui-Longquangang marginal shoal in the northern Hangzhou Bay as the study area, based on the measured and chart data from 1989 to 2014, we analyzed the topographic change of beach section and the variation characteristics of erosion and deposition of regional beach section along the Jinshanzui to Longquangang(JSZ-LQG) segment. The results showed that during study period there was relative stable eroded deepen channel in the study area, and the scouring and silting of the nearshore seabed showed a "fluctuating" law. The shallow area above 5 m water depth(2014) presented accreted patterns, meanwhile, seabed below 5 m water depth(2014) showed a general scouring trend since 1989. Moreover, variation of sediment discharge into the Yangtze River is an influencing factor of erosion/deposition in the study area. The typhoon waves, movement of the erosion and accretion sand body induced complexity in erosion and accretion in seabed of the JSZ-LQG segment.
An analysis on the phenomenon of increasing warmwater species abundance of phytoplankton in the Changjiang  (Yangtze River) Estuary during summer of 2017#br#
SUN Zhenhao, SHENG Liuyang, JIANG Xinqin, MA Xiao, WANG Bin, ZENG Jiangning, JIANG Zhibing,
Journal of Marine Sciences    2021, 39 (4): 82-90.   DOI: 10.3969/j.issn.1001-909X.2021.04.008
Abstract595)      PDF (2085KB)(467)      
The Changjiang (Yangtze River) Estuary has been subject to the double pressure of human activities and natural changes for a long time. As a result, the change of environmental factors may lead to a great alteration of phytoplankton community composition in this area. To explore the composition and variation of phytoplankton community in the Changjiang Estuary and compared with historical data, phytoplankton samples were collected vertically using net trawl method during “LORCE” cruise in August of 2017. Among all the samples collected, 7 phyla, 86 genera, and 205 species were identified, their total abundance was 1.47×105 cells/L. The results showed that diatoms and dinoflagellates accounted for 95.8% and 1.2% of the total phytoplankton abundance, respectively. Warmwater species, including Pseudonitzschia delicatissima (56.35×103 cells/L), Trichodesmium thiebautii (3.30×103 cells/L), Pseudosolenia calcaravis (3.05×103 cells/L), Chaetoceros lorenzianus (2.64×103 cells/L), Proboscia alata (1.89×103 cells/L) and Coscinodiscus gigas (1.71×103 cells/L), were dominant in the phytoplankton community. Their total abundance was 68.94×103 cells/L, which accounted for 47.00% of the total abundance of netcollected phytoplankton. High abundances of these warmwater species were observed near the front formed by the convergence of the Changjiang Diluted Water and Taiwan Warm Current. Spearman’s rank correlation showed that C. lorenzianus and P. calcaravis were negatively correlated with phosphorus, C. gigas were positively correlated with the concentrations of dissolved inorganic nitrogen, and P. calcaravis was positively correlated with salinity, C. lorenzianus and C. gigas were negatively correlated with salinity. Compared with the summer dominant phytoplankton species during the past 30 years, it was found that warmwater species of phytoplankton in the Changjiang Estuary increased significantly and their distribution area expanded northward. It was speculated that this phenomenon was highly associated with sea temperature elevation and the enhancement of warm current.

The seasonal blooming characteristics of phytoplankton and POC export flux in the waters around South Georgia Island: Based on BGC-Argo and satellite remote sensing observations
ZHAO Yueran, FAN Gaojing, WU Jiaqi, SUN Weiping, PAN Jianming, HAN Zhengbing
Journal of Marine Sciences    2023, 41 (4): 1-11.   DOI: 10.3969/j.issn.1001-909X.2023.04.001
Abstract218)   HTML40)    PDF (2882KB)(373)      

The waters surrounding South Georgia Island are one of the highest primary productivity regions in the Southern Ocean with enormous carbon sequestration potential. However, the strength of the biological pump efficiency in this area is still uncertain due to the lack of continuous upper ocean observation data.In this study, the hydrological and biogeochemical parameters obtained from the Biogeochemical Argo (BGC-Argo) floats deployed in the South Georgia Island vicinity during the period of 2017-2020 were utilized to investigate the impacts of physical processes on biogeochemical processes and to estimate the carbon export flux in the Antarctic summer. Results indicated that both upstream (northeast of the Antarctic Peninsula) and downstream (Georgia Basin) regions of South Georgia Island exhibited strong seasonal characteristics in Chl-a, with the latter area having a 4-month sustained period of phytoplankton bloom, suggesting a stable and continuous supply of iron. Using the temporal variability of the seasonal particulate organic carbon (POC) export, the summer POC export fluxes of the upstream and downstream regions were estimated to be 7.12±3.90 mmol·m-2·d-1 and 45.29±5.40 mmol·m-2·d-1, respectively, indicating that the difference might be due to enhanced downward export of organic carbon after the deepening of the mixed layer. The study found that the region maintained a high biological pump efficiency, contrary to the previous conclusion that the Georgia Basin had “high productivity low export efficiency”, which might have been caused by the limited “real-time” representation of the entire seasonal characteristics during ship-based surveys. BGC-Argo provides high spatiotemporal resolution of multi-parameter observation data, and this study demonstrates that it can more accurately quantify and evaluate marine biogeochemical processes and carbon sequestration potential.

Distribution characteristics of chlorophyll a and the exploration of its influencing factors in Beibu Gulf, August-September 2021
Journal of Marine Sciences    2022, 40 (3): 142-152.   DOI: 10.3969-j.issn.1001-909X.2022.03.013
Abstract388)      PDF (3588KB)(386)      
Chlorophyll a (Chl a), as the main pigment of phytoplankton photosynthesis, is often used to indicate the existing amount of phytoplankton in water column. The concentration of Chl a in Beibu Gulf from August to September 2021 was analyzed and its spatial distribution characteristics and influencing factors were discussed based on the summer cruise of the Shiptime Sharing Program on 2020 Beibu Gulf Scientific Research Expedition. The results showed that the mass concentration of Chl a ranged from 0.03 to 10.59 μg/L with an average value of 0.84 μg/L, among which the surface layer mass concentration ranged from 0.08 to 10.59 μg/L (average 0.97 μg/L) and the bottom layer mass concentration ranged from 0.03 to 4.69 μg/L (average 0.99 μg/L). Combined with the analysis of remote sensing data, the spatial distribution of Chl a mass concentration in Beibu Gulf was generally high in the nearshore and low in the offshore area. The high value area was mostly distributed in the nearshore area of Guangxi, namely the northern part of Beibu Gulf, while the mass concentration in the central and southern part of Beibu Gulf was relatively low. The correlation analysis between water environmental parameters and Chl a indicated that water nitrogen limitation was an important factor affecting the mass concentration of Chl a in Beibu Gulf from August to September.

Seasonal variations of mesoscale eddy in the Bay of Bengal and its adjacent regions
HUANG Ting, ZHOU Feng, TIAN Di, ZHANG Jiaying
Journal of Marine Sciences    2020, 38 (3): 21-30.   DOI: 10.3969/j.issn.1001-909X.2020.03.003
Abstract346)      PDF (5650KB)(367)      
Distribution of eddy originations and characteristics of eddies in summer and winter in the Bay of Bengal (BOB) from 1993 to 2017 were analyzed based on Mesoscale Eddy Trajectory Atlas Product provided by AVISO. Seasonal variabilities of mesoscale eddies were found mainly in the western BOB, the Andaman Sea and the southern BOB. Eddies in the Andaman Sea distribute from north to south with order of “anticyclones-cyclones-anticyclones” and “cyclones-anticyclones-cyclones” in winter and summer respectively. Growth of eddies has seasonal variabilities and varies from different regions. Eddies in the western BOB intensify rapidly but vanish slowly in summer. Sri Lanka cold eddies intensify slowly but vanish rapidly. Amplitude and radius of eddies are different in different regions. Amplitude and radius of anticyclones are larger than those of cyclones whenever in summer or winter in the western BOB. Radius of anticyclones is larger than that of cyclones near the Southwest Monsoon Current. While, amplitude of anticyclones is smaller than that of cyclones. Amplitude and radius of eddies northernmost are the largest whenever in summer or winter in the Andaman Sea. Eddies with lifetime about 30-40 days are the largest number in the Bay of Bengal. Eddies with long lifetime mainly distribute in the western BOB.
Analysis of measured wave characteristics in the coastal waters of Cangnan, Zhejiang Province
ZHOU Yiming, YANG Lihua, HUAN Caiyun, LIU Rong
Journal of Marine Sciences    2023, 41 (3): 43-55.   DOI: 10.3969/j.issn.1001-909X.2023.03.005
Abstract178)   HTML11)    PDF (4079KB)(393)      

Based on the one-year measured wave data in the coastal area of Cangnan, Zhejiang Province, the characteristics of wave parameters were statistically analyzed, the correlation between wave parameters was analyzed by using the least square method, the relationship between the average wave duration and wave height was studied, the wave energy was estimated, and the characteristics of typical typhoon waves during typhoon “Lekima” were analyzed.The results show that the study area is mainly composed of light waves with spectral peak period of 5-9 s, the annual average significant wave height of 1.22 m, the normal wave direction is E, the strong wave direction is ENE.There is a significant linear relationship between the characteristic wave heights, which conforms to the typical Rayleigh Distribution.In typhoon free period and cold wave free period with significant wave height below 2.7 m and typhoon period with significant wave height above 4.1 m, the average duration of wave decreases exponential decays with the increase of wave height, and the attenuation rate of typhoon period with significant wave height above 4.1 m is higher than that of typhoon free period and cold wave free period with significant wave height below 2.7 m.During the impact of typhoon “Lekima”, the maximum wave height, spectral peak period, and spectral peak density show a basically synchronous process of first increasing and then decreasing, with a maximum spectral peak density of 55.10 m2/Hz;the typhoon wave spectrum before and after the impact of the typhoon show a bimodal spectrum, while the wave spectrum during the most significant period of typhoon impact show a unimodal spectrum.

Carbon cycling in costal ocean and CO 2 negative emissions
YU Lei, LI Sanzhong, SUO Yanhui, WANG Xiujuan
Journal of Marine Sciences    2023, 41 (1): 14-25.   DOI: 10.3969-j.issn.1001-909X.2023.01.002
Abstract534)   HTML40)    PDF (2925KB)(516)      

Costal ocean receives a bunch of carbon materials and nutrients from terrestrial sources, relates a lot of carbon-involving interactions. Meanwhile, it is normal that sedimentary reservoir-cap systems with good trap conditions beneath coastal ocean, these entrapments have potentials to storage CO2. This review focuses on the coastal ocean as the research object, and introduces the carbon cycle processes in coastal ocean, their factors which could influence CO2 fluxes in the carbon cycle processes, and the potential carbon storage mechanisms of the coastal marine sedimentary basins. From the perspective of “carbon peaking and carbon neutrality”, the significance of coastal oceans for “Ocean Negative Carbon Emission (ONCE)”, its potential promotion paths, carbon storage potentials in sedimentary basins and the problems faced by coastal oceans are discussed. Overall, the costal ocean is one of the important blue carbon sink areas. In the coastal marine seawater system, improving the reaction efficiency of microbial carbon pump and carbonate carbon pump have positive significance for CO2 negative emissions; The suitable reservoir-cap systems for CO2 storage beneath coastal ocean can not only provide extra spaces, but also guarantee the safety for CO2 storage. In the future, the main research directions should be to inhibit the conversion process of carbon materials to CO2 in coastal oceans and ensure the safety of CO2 storage in sedimentary reservoirs, these could provide theoretical basis and technical guarantee for CO2 negative emissions.

Analysis of the spatial and temporal variation of Thailand coastline from 1990 to 2020
LUO Zhengyu, ZHANG Li, CHEN Bowei, SUN Hao, BI Jingpeng
Journal of Marine Sciences    2021, 39 (1): 56-66.   DOI: 10.3969/j.issn.1001-909X.2021.01.007
Abstract431)      PDF (12331KB)(216)      
As a sign element, a large range, long-term shore dynamic changes in the coastal zones, are of great significance to the research of regional coastal environment and human activities. Used the remote sensing techniques, the variation characteristics of Thailand shoreline from 1990 to 2020 was analyzed, such as length changes, type changes, change rate, and the “sea-land” pattern. The results show that: (1) For 30 years, the length of the shoreline of Thailand had a continuous growth trend, but the growth rate was fast at first and then slow down, which patterns were expressed as two kinds: sea-forward expansion and land-forward erosion. From 1990 to 2015, the expansion trend in the shoreline toward the sea gradually slowed, and the erosive trend in the land was gradually increased. The overall change trend from 2000 to 2015 was mainly erosion, but the overall shoreline change in 2015 was expanded to the sea. (2) Thailand shoreline regional variation was significant, the change in the expansion of the banks such as Leam ChaBang was dramatic, and the erosion change in the northern part of Bangkok Bay was obvious. (3) The main driving force for the expansion of Thailand shoreline was the construction of coastal projects, and the main factors of erosion variations were the ocean environment and extreme climate, while policy management acted on the whole process of straighten changes.