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Reconstruction of sea surface temperature from DINEOF-based FY polar-orbiting meteorological satellite
SONG Wanjiao, ZHANG Peng, SUN Ling, TANG Shihao, ZHOU Fangcheng,
Journal of Marine Sciences    2022, 40 (2): 10-18.   DOI: 10.3969-j.issn.1001-909X.2022.02.002
Abstract719)      PDF (3384KB)(2305)      
Sea surface temperature (SST) is the critical factor for depicting the marine thermal distribution. Daily global SST data sets support the typhoon elaborated monitoring and other marine disasters forecast. SST products retrieved by the visible infrared radiometers and mediumresolution imagers have high spatial resolution, while the SST products retrieved by infrared remote sensing are affected by clouds, fog and haze, and therefore a large areas under the clouds are lack of value. SST products retrieved by the microwave radiometer have low spatial resolution, while the microwave could penetrate the cloud layer to achieve all-weather sea surface observation. The data interpolation empirical orthogonal function method (DINEOF) was used to reconstructed the global SST products, and FY-3 (Fengyun 3) SST data sets were applied in this study, which included the SST data sets from the FY-3B/FY-3C Visible and Infra-Red Radiometer, FY-3D Medium Resolution Spectral Imager and FY-3D Micro-Wave Radiation Imager. Accuracy of the reconstructed data sets was verified using OISST measurements to demonstrate the validity and reliability of the DINEOF method. The results show that DINEOF reconstructed sea surface temperature (DSST) data are validated reliable. Root mean square error of the original data is ranging from 0.59 ℃ to 0.70 ℃, while the reconstructed data is relatively stable, ranging from 0.10 ℃ to 0.34 ℃. Correlation coefficient obvious raises from 0.33-0.48 to 0.78-0.98. Multi-sensors reconstructed SST products is continuous and credible in spatial distribution and monitor the variation of warm pool from spring to winter. Addition of FY-3D microwave SST products has significantly improved the spatial continuous distribution and temporal resolution of reconstructed SST.
Explorations of marine gas hydrate deposits and the signatures of hydrocarbon venting using in situ techniques
LIU Liping, CHU Fengyou, GUO Lei, LI Xiaohu
Journal of Marine Sciences    2023, 41 (1): 26-44.   DOI: 10.3969-j.issn.1001-909X.2023.01.003
Abstract413)   HTML1736)    PDF (4566KB)(1247)      

Marine gas hydrate deposits are significant temporal reservoirs for hydrocarbons migrating from deep sources. This is crucial to our understanding of ocean carbon cycling. The cold seep, a geological process regarding gas leakage from deep or shallow sources, is usually linked with gas hydrate decomposition. In this thesis, we reviewed the latest applications of in situ monitoring and detecting methods regarding the leakage plumes, migration pathways, and seafloor geomorphologies associated with gas hydrate and cold seep systems, primarily including vessel-and land-based gas plume measurements, surface ocean-lower atmosphere hydrocarbon emission detections, seafloor visualization techniques, and in situ observation networks. The integrated applications of these in situ observation methods provide a nuanced view of the temporal and spatial variability of hydrate and cold seep systems, facilitate understanding of the fate of hydrocarbons, and expand our knowledge of cold-seep biota in a watery desert.

Study on tide and tidal current near the Changjiang (Yangtze River) Estuary based on observational data
ZENG Dingyong, XUAN Jiliang, HUANG Daji, et al
Journal of Marine Sciences    2022, 40 (1): 12-20.   DOI: 10.3969/j.issn.1001-909X.2022.01.002
Abstract1699)      PDF (2926KB)(972)      
There is strong tide in the Changjiang (Yangtze River) Estuary and its adjacent area. Except for the coast area, there is a lack of longterm tide level and tidal current data in the offshore area. Long time series of water level observation data was used in this study, and the results reveal that the tidal type in the Changjiang Estuary is a regular semidiurnal tide, with a significant shallow water division in the nearshore area; the M2 division is the most significant semidiurnal tide, and the amplitude tends to increase from the open sea in the east to the shallow water or island group at the mouth of Hangzhou Bay in the west. The M2 tidal current is the most significant semidiurnal tidal current, and the rotating tide is the most significant semidiurnal tide. The two stations to the south of the Changjiang mouth are rotating counterclockwise, while the stations to the east of the mouth are rotating clockwise. The vertical structure of the tide has significant spatial differences, the ellipticity of the M2 tidal current is mostly negative, the ellipticity of the M2 tidal current, the direction and the arrival time of maximum velocity all vary significantly with depth.

Comparison of methods for calculating bottom shear stress based on intertidal flat field data
SUN Jianxiong, ZHANG Wenxiang, SHI Benwei
Journal of Marine Sciences    2022, 40 (1): 21-32.   DOI: 10.3969/j.issn.1001-909X.2022.01.003
Abstract583)      PDF (2851KB)(791)      
As a key parameter in hydrodynamic and sediment transport models, bottom shear stress is very important to study the initiation and erosion rates of bottom sediment. At present, there are six theoretical methods for calculating bottom shear stress based on field measured flow velocity data: LPmean method, LPmax method, TKE method, TKEW method, RS method and ID method, all of which have their specific applicable conditions. It is very important to select an appropriate method to calculate the bottom shear stress in the shallow water area of estuarine and coastal areas where the actions of current and wave are complex. In this study, one observation site at Dafeng Doulong Port, Jiangsu Province (median particle size: 68.56 μm) and two observation sites at Eastern Chongming Shoal, Shanghai (median particle size: 12.89 μm and 45.02 μm) were taken as examples. Field data were collected using Acoustic Doppler Velocimetry and wave measurement instrument (RBRwave), and the bottom shear stress was calculated by six theoretical methods. The results show that: (1) The LPmean method is affected by the average velocity, the distance from the probe to bed and the strength of waves, which underestimates the bottom shear stress and is not suitable for shallow water environment in intertidal flat; (2) LPmax method and TKE method can overestimate shear stress in shallow water environment of intertidal flat where flow velocity varies greatly and wave action is obvious; (3) TKEW method was modified on the basis of TKE method, which is more suitable for solving the bottom shear stress under strong wave action; (4) The results of RS method are affected by waves, and the results of ID method are more reliable than those of RS method when large waves exist, but ID method will overestimate the bottom shear stress when water depth is insufficient.
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.
Qiongzhou Strait as a self-adapted low-passing filter?
LI Yan
Journal of Marine Sciences    2022, 40 (3): 9-16.   DOI: 10.3969-j.issn.1001-909X.2022.03.002
Abstract395)      PDF (1618KB)(689)      
Since a diagram depicting "The Great Ocean Conveyor" was first appeared as a logo by Wally Broecker in 1987, how the warmed upper ocean circulation ran through the Indonesian Seas with their complex coastline geometry and narrow passages, known as the Indonesian through-flow, becomes one of the difficult settings in boundary conditions of climate change model. With strong nonlinear effect, a shallow narrow passage forms vertical mixed hotspots on the one hand, and on other hand, it becomes a self-adapted low-pass filter if the tidal resonance units are introduced. Qiongzhou Strait, a sufficient sediment supply and shallow narrow passage for the northern shelf of the South China Sea, is reported with strong tidal current and westward through-flow. And its tidal channel and tidal deltas are maintained by the tidal resonance units introduced themself. Strong disturbances such as typhoon and cold wave can cause storm jet flow through the strait, triggering different high nutrition, algal bloom and hypoxia events over the adjacent Beibu Gulf. Qiongzhou Strait seems to be a noteworthy case of studying how the self-adapted low-pass filter introduced and whether human activities can affect the through-flow on the shallow narrow passages.

Assessment of carbon sink potential and driving factors of island forests on national nature reserve
WU Liangxu, ZOU Huimin, CHEN Wei, XU Minghai, CAI Houcai, CHEN Shuyi, LI Xianglan
Journal of Marine Sciences    2023, 41 (1): 96-109.   DOI: 10.3969-j.issn.1001-909X.2023.01.008
Abstract375)   HTML17)    PDF (4905KB)(687)      

The monitoring of carbon flux dynamics and assessment of carbon sink functions of island forest ecosystems are rarely reported due to their special geographical location and few data sources. In this study, the forest ecosystem of the Nanji Island was used as the research object, the carbon sink potential of island forests and their driving factors were assessed. Based on eddy correlation techniques, the temporal variation characteristics and driving factors of net ecosystem productivity (NEP), gross primary productivity (GPP), and ecosystem respiration (Reco) from 2020 to 2021 were explored. Results showed that the forest ecosystem of Nanji Island was carbon sink. Net CO2 uptake in 2020 and 2021 were 516 g C·m-2·a-1 and 598 g C·m-2·a-1, Reco were 1 037 g C·m-2·a-1 and 1 646 g C·m-2·a-1, and GPP were 1 552 g C·m-2·a-1 and 2 244 g C·m-2·a-1, respectively. Total solar radiation (Rg), photosynthetically active radiation (PAR), net radiation (Rn) and sensible heat (H) were significantly and positively correlated with NEP and GPP (p≤0.001); air temperature (Tair) and soil temperature (Tsoil) were significantly and positively correlated with Reco(p≤0.001). The photosynthesis time of Nanji Island forest was longer than the carbon sink time on the daily scale. When Tair reached 10.05-27.76 ℃ and PAR reached 110.47-429.44 μmol·m-2·s-1, the photosynthesis intensity of island forest was higher than that of ecosystem respiration, which showed CO2 absorption. The monitoring and assessment of carbon fluxes in the forest ecosystems of Nanji Island will provide an important theoretical support for the establishment of a dynamic monitoring and assessment management system for blue carbon in China.

Research on convenient calibration method of optical dissolved oxygen sensor based on air medium
GAO Shun, ZHANG Yingying, YUAN Da, et al
Journal of Marine Sciences    2022, 40 (1): 81-88.   DOI: 10.3969/j.issn.1001-909X.2022.01.009
Abstract448)      PDF (1681KB)(675)      
Optical dissolved oxygen sensor based on fluorescence quenching principle can obtain spatiotemporal data of dissolved oxygen in seawater, which is widely used in long-term monitoring of marine environment. However, due to the “storage drift” and “measurement drift” occurring during storage and distribution, it is necessary to calibrate and correct the data drift of the instrument. Existing calibration methods have long cycle and complex operation. In this project, the response characteristics of optical dissolved oxygen sensor in air and water medium were studied, and a field calibration method of optical dissolved oxygen sensor using air medium was proposed, and a two-point calibration model of the instrument was established. Experimental results show that the calibration method can effectively correct the data drift of the dissolved oxygen sensor, and the deviation between the measured value of the sensor and the standard value of Winkler titration is within  ±6 μmol·L-1. This method can realize the convenient and rapid correction of optical dissolved oxygen sensor, avoid the tedious steps of laboratory maintenance, improve the quality of monitoring data, maintain the continuity of monitoring data, and has important application value.

Seasonal variation of water masses and current field in the northeastern Beibu Gulf based on observations in 2018-2019
Journal of Marine Sciences    2022, 40 (3): 73-85.   DOI: 10.3969-j.issn.1001-909X.2022.03.007
Abstract414)      PDF (6105KB)(670)      
 Hydrological observations were carried out in the northeastern of Beibu Gulf in July and October 2018, February 2019 to reveal its seasonal variations. Sectional measurements of temperature, salinity and current velocity were deployed to the north of 18°N and east of 108°E. The results show that there is obvious seasonal disparities on the character of water masses in this region: the sea water temperature in summer decreases from northern shallow water to southern deep region and the onshore brackish water dominates the area shallower than 30 m, and a occlusive cold water mass appears in deep layer to the west of Hainan Island; while in winter the water temperature increases from north to south, the brackish water shrinks to the northern coast shallower than 10 m, the area is occupied mainly by the mixed water, and a warm tongue appears in upper layer on the west of Hainan Island. The circulation in the research region is mainly counterclockwise in all three seasons, though the strength of current varies in different seasons, and is significantly influenced by wind. The water exchange between the northeastern gulf and outer ocean is not active, since the observed salinity is entirely less than 34. The water mass is generally shear instable, and static instability appears in winter. This suggests that the diapycnal mixing in this region might be strong. 

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.

Marine magnetotelluric reveals the resistivity structure of the Suda Seamount in the western Pacific Ocean
JIANG Jie, ZHANG Tao, CAI Xiaoxian, WU Zhaocai,
Journal of Marine Sciences    2022, 40 (2): 42-52.   DOI: 10.3969-j.issn.1001-909X.2022.02.005
Abstract480)      PDF (4125KB)(664)      
In order to study the deep resistivity structure of intraplate volcanoes and their formation processes, a marine magnetotelluric survey at Suda Seamount in the western Pacific Ocean was conducted. The mainstream data processing method SSMT2000 was used for data processing. The measured data after rotation and the two groups of rotation invariants obtained from the measured data were tested for magnetotelluric response under the assumption of one-dimensional structure, and one-dimensional inversion was conducted for the YX direction data with the best response. Combined with one-dimensional forward modeling and other geological data, the inversion results were comprehensively interpreted. The inversion results show that the thickness of the crust at Suda Seamount is about 21.5 km. The thick volcanic clastic rocks indicate that the formation of Suda Seamount is mainly eruptive and weakly intrusive.
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.

Interactions between vegetation and sediment carbon pools within coastal blue carbon ecosystems: A review and perspective
CHEN Yining, CHEN Luzhen
Journal of Marine Sciences    2023, 41 (1): 3-13.   DOI: 10.3969-j.issn.1001-909X.2023.01.001
Abstract781)   HTML301)    PDF (1348KB)(614)      

Mangroves, coastal salt marshes and seagrass beds, as the typical coastal blue carbon ecosystems, have been widely recognized for their remarkable capacity in carbon storage. Vegetation carbon pool and sediment (or soil) carbon pool were considered to be the major carbon pools within the coastal blue ecosystems and their variations determined the overall carbon sequestration of the ecosystems. From a perspective of carbon pool interactions, this study summarized the previous research work based on literature review, including the interactions within various vegetation carbon pools and within various sediment carbon pools, as well as the interactions between vegetation and sediment carbon pools. Interspecific competition, allochthonous carbon input and biogeomorphology were found to be the key to understand the carbon pool interactions. Finally, a perspective on the current state-of-the-art of blue carbon pool study is offered, with challenges and suggestions for future directions.

Driving force of marine sedimentary source to sink: A case study from Beibu Gulf
Journal of Marine Sciences    2022, 40 (3): 17-32.   DOI: 10.3969-j.issn.1001-909X.2022.03.003
Abstract487)      PDF (3784KB)(587)      
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)(558)      

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.

Study on orbit calculation of HY-1C satellite
LIU Jianyang, MAO Zhihua, SHI Yi
Journal of Marine Sciences    2022, 40 (1): 53-63.   DOI: 10.3969/j.issn.1001-909X.2022.01.006
Abstract812)      PDF (2798KB)(531)      
Orbital data are important parameters involved in the satellite data processing and HY1C satellite products with high quality are inseparable from the accurate calculation of the orbit. In this study, data were extracted from the TLE (TwoLine Orbital Element) and used to accurately simulate satellite orbit based on STK (Satellite Tool Kit) software. The ephemeris was outputted to compare the accuracy of two satellite orbit algorithms of HY1C and evaluate the influence of perturbation factors on orbit calculation. Method one uses an algorithm which does not consider perturbation factors and extrapolates the ephemeris parameters of the observation time based on the orbit elements of the reference time, and then calculates the satellite orbit data. Method two adopts the SGP4 model which considers perturbation to calculate the orbit data. The results show that perturbation has a significant impact on the orbit calculation. The algorithm error without considering the perturbation increases significantly with the passage of time, and the position errors are less than 10 km with the speed errors less than 10 m/s in half an hour. While SGP4 model algorithm runs fast with high calculation accuracy and good stability, the position and speed errors within 24 hours are less than 68 m and 0.051 m/s respectively. Therefore, SGP4 model algorithm can be used for the highprecision orbit calculation of the loworbit satellite HY1C.

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.

Distributional characteristics and influencing factors of storm surge in Haikou
LIANG Haiping, LI Tuanjie, LIANG Haiyan, GAO Lu
Journal of Marine Sciences    2022, 40 (2): 83-92.   DOI: 10.3969-j.issn.1001-909X.2022.02.009
Abstract375)      PDF (2556KB)(509)      
Based on the measured water level data of Xiuying Station from 1980 to 2017, the distributional characteristics and influencing factors of storm surge in Haikou were studied by using the methods of statistical analysis and numerical model. It is found that Haikou is frequently affected by typhoon storm surge, with an annual average of 2.79 times, which usually occurs from July to October, and the probability of tidal disaster caused by storm surge is high. The horizontal distribution of storm surge shows that the storm surge intensity of Dongzhai Port ranks first, followed by Xiuying Port, Haidian Island and South Port. Influencing factors show that the weight of topography is usually greater than the moving path of tropical cyclone storm surge in Haikou; when the moving speed of tropical cyclone is 14-19 km/h, the storm surge in Haikou is usually the largest.
Dynamics of mangrove change: Insights from 30-year observations of Maowei Sea
Journal of Marine Sciences    2022, 40 (3): 132-141.   DOI: 10.3969-j.issn.1001-909X.2022.03.012
Abstract355)      PDF (2173KB)(505)      
Understanding the spatial evolution of mangrove patches is important to comprehensively and accurately evaluate the results of protection and restoration efforts in regional mangroves. In this study, the recent 30-year changes in area and number of mangrove patches in Maowei Sea and their driving factors were analyzed. The 1990, 2000, 2010 and 2019 Landsat remote sensing images were used as the main data sources, whereas the landscape dynamic analysis, spatial overlay analysis and main transformation route counting were adopted as the analytical approaches. The results demonstrated that: (1) The area of mangrove in Maowei Sea increased from 479.7 hm 2 to 1 477.5 hm 2 between 1990 and 2019 with the centroid shifting northward and westward. (2) Anthropogenic and natural factors were identified as the main driving force leading the changes in mangrove patch quantity in Maowei Sea from 1990 to 2010 and 2010 to 2019, respectively. (3) The number of mangrove patches increased from 204 in 1990 to 405 in 2019. However, the simultaneous occurrence of declining patch density and increasing mean patch size indicated that the patch fragmentation had been alleviated caused by the driving of natural factors. The artificial plantation of mangroves, especially using Sonneratia apetala, had contributed to the overall increase in mangrove area in Maowei Sea. Nevertheless, research on the artificial forestation process, expansion mechanism of mangrove patches and their ecological effects should be emphasized in future.

Characteristics of tide, tidal current and their effects on nutrients in Xincun Lagoon, Hainan Island
ZHANG Yipu, YU Shuo, HUANG Daji, ZHOU Zebin,
Journal of Marine Sciences    2022, 40 (2): 69-82.   DOI: 10.3969-j.issn.1001-909X.2022.02.008
Abstract590)      PDF (5177KB)(502)      
Based on the measured hydrological and water quality data of Xincun lagoon in December 2020, the characteristics of tide in Xincun lagoon were studied, and the effects of tidal elevation changes on nutrients in Xincun lagoon were discussed. The results show that the tide of Xincun lagoon is irregular diurnal. The tidal current at the inlet of the lagoon is a reciprocating current, lasting 15 h for flood tide and 10 h for ebb tide. The concentration of dissolved inorganic nitrogen (DIN), phosphate (PO3-4) and silicate (SiO2-3) vary from 0.91 to 20.87 μmol/L, 0.11 to 5.92 μmol/L and 2.36 to 134.75 μmol/L respectively. The concentrations of DIN, PO3-4 and SiO2-3 at the observation sites in the lagoons changed with the flood and ebb of the tidal process. The flow velocity at the inlet of the lagoon has an important influence on the change of tidal elevation at the observation sites, and the tidal flux basically determines the change of tidal elevation at the observation sites. There is a significant negative correlation between the nutrient concentration at the inlet of the lagoon and at the mariculture area and the tidal elevation, and the tidal current velocity has an important effect on the nutrient concentration at the inlet of the lagoon and the mariculture area. The results will provide scientific basis for pollution control and ecological restoration of Xincun lagoon.