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  • 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.

  • Study on frequency shift of typhoon-excited near-inertial waves in northwestern South China Sea
    FU Dianfu, XIE Botao, HUANG Bigui, JIN Weifang, MOU Yong, LIN Feilong

    Near-inertial waves (NIWs) play an important role in the response of ocean to typhoon. Their frequency varies with the depth and is the main factor in determining the propagation rate of near-inertial energy to the ocean interior. Based on the observation data from mooring, the factors affecting the blue-shift frequency of NIWs excited by typhoon were investigated in northwestern South China Sea. By analyzing the vorticity effect and Doppler effect caused by background currents, this study suggests that the Doppler effect of background currents was the main factor in the blue-shift frequency of NIWs. As depth increased, inertial wave frequencies increased. Quantitative calculations further demonstrated that within the upper 200 meters, the Doppler effect of the background currents was negative, approaching zero in depth around 200 meters. However, in the depth range of 230 to 400 meters, the Doppler effect became positive. This depth range exhibited the maximum strength of the background currents, with their direction aligned with the propagation direction of inertial waves. Consequently, the positive Doppler shift induced by the background currents was most pronounced. The results of this study are important for improving the understanding of the ocean response to typhoons, especially the propagation of near-inertial waves in areas with complex background current structure (e.g., the western boundary current region).

  • Numerical investigation of the super typhoon Mangkhut based on the coupled air-sea model
    LÜ Zhao, WU Zhiyuan, JIANG Changbo, ZHANG Haojian, GAO Kai, YAN Ren

    Based on the mesoscale atmospheric model WRF and the regional ocean model ROMS, a two-way coupled WRF-ROMS air-sea model was constructed to simulate the super typhoon Mangkhut in 2018. The results showed that the simulation results of the coupled air-sea model were better than those of the only atmospheric or ocean model, and the error of the typhoon track obtained from the coupled model was within 60 km, which was in good agreement with the best track. Compared with the observation results, the simulation results of wind speed and sea level pressure in the coupled model were better than others model. Based on the simulation results of the coupled air-sea model, the spatial and temporal distribution of the wind field, pressure field, sea surface flow field, and storm surge under the super typhoon Mangkhut were further analyzed. The results showed that: (1) In terms of spatial distribution, after the typhoon entered the South China Sea, the radius of the seven-level wind circle was larger behind the right side of the typhoon; the cyclonic flow field showed a significant Ekman effect with the typhoon wind field, and the flow direction was 45° from the wind direction. The wind field, pressure field, wind-generated flow field and water gain distribution all had obvious asymmetry, and the typhoon intensity, flow velocity and water gain were greater on the right side of the typhoon path than on the left side. (2) In terms of time distribution, the distribution of the wind field and the pressure field were similar and synchronized with the typhoon center, while the wind-driven flow field and storm surge were three hours behind the typhoon track.

  • 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
    2023, 41(4):1-11. DOI:10.3969/j.issn.1001-909X.2023.04.001
    Abstract ( 84 ) HTML ( 17 ) PDF ( 2882KB ) ( 54 )   
  • Study on frequency shift of typhoon-excited near-inertial waves in northwestern South China Sea
    FU Dianfu, XIE Botao, HUANG Bigui, JIN Weifang, MOU Yong, LIN Feilong
    2023, 41(4):12-20. DOI:10.3969/j.issn.1001-909X.2023.04.002
    Abstract ( 70 ) HTML ( 7 ) PDF ( 2573KB ) ( 31 )   
  • Numerical investigation of the super typhoon Mangkhut based on the coupled air-sea model
    LÜ Zhao, WU Zhiyuan, JIANG Changbo, ZHANG Haojian, GAO Kai, YAN Ren
    2023, 41(4):21-31. DOI:10.3969/j.issn.1001-909X.2023.04.003
    Abstract ( 81 ) HTML ( 9 ) PDF ( 8056KB ) ( 49 )   
  • Numerical simulation study on influences of onshore wind on overtopping characteristics of solitary wave under coastal seawall
    ZHANG Liangbin, QU Ke, HUANG Jingxuan, WANG Xu, GUO Lei
    2023, 41(4):32-45. DOI:10.3969-j.issn.1001-909X.2023.04.004
    Abstract ( 46 ) HTML ( 4 ) PDF ( 5147KB ) ( 23 )   
  • Deep-sea rare earth resource potential in the Eastern Pacific Clarion-Clipperton Fracture Zone: Constraint from sediment geochemistry
    WU Xinran, DONG Yanhui, LI Zhenggang, WANG Hao, ZHANG Weiyan, LI Huaiming, LI Xiaohu, CHU Fengyou
    2023, 41(4):46-56. DOI:10.3969/j.issn.1001-909X.2023.04.005
    Abstract ( 51 ) HTML ( 6 ) PDF ( 5603KB ) ( 20 )   
  • Simulation study on oblique in situ acoustic longitudinal wave measurement of seafloor inhomogeneous sedimentary layer
    WANG Ying, TAO Chunhui, ZHANG Guoyin, ZHOU Jianping, SHEN Honglei
    2023, 41(4):57-69. DOI:10.3969/j.issn.1001-909X.2023.04.006
    Abstract ( 46 ) HTML ( 2 ) PDF ( 5319KB ) ( 28 )   
  • Vulnerability and driving factors of coastal erosion: A case study of the central coast of Jiangsu
    ZHANG Zhi, LIU Xianguang, ZHOU Kai, LIN Weibo, MAO Shifeng, LI Lanman
    2023, 41(4):70-83. DOI:10.3969/j.issn.1001-909X.2023.04.007
    Abstract ( 52 ) HTML ( 4 ) PDF ( 3352KB ) ( 28 )   
  • Research of carbon storage assessment of island vegetation based on UAV multispectral remote sensing:A case study of Dazhuzhi Island in Dongtou
    XIE Jiaqi, ZHANG Zhao, ZHOU Wen, WANG Jinwang, CHEN Yahui
    2023, 41(4):84-93. DOI:10.3969/j.issn.1001-909X.2023.04.008
    Abstract ( 72 ) HTML ( 10 ) PDF ( 3792KB ) ( 36 )   
  • Effects of different vegetation types on the source and storage of organic carbon in muddy tidal flats: Taking Maoyan Island as an example
    LIU Yuwei, YU Peisong, ZHENG Minhui, ZHAO Zhengjia, ZHANG Cai, HAN Chenhua
    2023, 41(4):94-101. DOI:10.3969/j.issn.1001-909X.2023.04.009
    Abstract ( 51 ) HTML ( 8 ) PDF ( 2419KB ) ( 28 )   
  • Macrobenthos community and living organic carbon pools on muddy tidal flat: Implications from Aiwan Bay of Wenling in summer
    TIAN Sujie, TANG Yanbin, YU Peisong, LIU Chenggang, LIU Qinghe, ZHANG Rongliang, SHOU Lu, ZENG Jiangning, LIAO Yibo
    2023, 41(4):102-112. DOI:10.3969/j.issn.1001-909X.2023.04.010
    Abstract ( 57 ) HTML ( 5 ) PDF ( 1642KB ) ( 22 )   
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