• Topics


    Not found
    Big data of oceanography
    Default Latest Most Read
    Please wait a minute...
    For Selected: Toggle Thumbnails
    The impaction of typhoon on seafloor ambient noise by analyzing the OBS recording data
    AO Wei, ZHAO Ming-hui,RUAN Ai-guo,QIU Xue-lin
    Journal of Tropical Oceanography    2009, 28 (6): 61-67.   DOI: 10.11978/j.issn.1009-5470.2009.06.061
    Abstract2636)      PDF(pc) (4891KB)(1910)       Save

    Ocean Bottom Seismometer (OBS) deployed in the seafloor can record information of ocean ambient noise, and typhoon can generate elastic waves propagating through the seafloor directly or indirectly. These factors cause great changes on OBS recording data to some extent. The OBS data during the process of typhoon was analyzed, and the methods of optimum filter were used in order to separate signals. After those work, we found that wind wave and ground swell were well recorded by short-period OBSs for the first time, and a new mode which typhoon affected seafloor ambient noise was put forward. We get three preliminary conclusions from above analysis: (1) Wind wave and ground swell caused by typhoon have their own distinctive modes to affect seafloor ambient noise;(2)The range and extent of seafloor ambient noise are obviously different which have been strengthened by two above waves;(3)Short-period OBSs can clearly record the information of ground swell, whose dominating period is 6—8 seconds and its energy is generally steady (we call it “8-second phenomenon); These results will have great significance for the future research on marine seismology and other aspects of oceanography.

    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(4) CSCD(5)
    Ocean Environmental Three-dimensional Monitor by AUV
    LI Ye1,2, PANG Yong-jie1,2, TANG Xu-dong1,2
    Journal of Tropical Oceanography    2009, 28 (4): 12-16.   DOI: 10.11978/j.issn.1009-5470.2009.04.012
    Abstract1899)      PDF(pc) (1770KB)(1594)       Save
    Autonomous underwater vehicle (AUV) can be used for monitoring three-dimensional marine environment, thanks to its characters of covering large area and strong automation. The authors introduce marine monitoring technology by AUV in the world, and then present their own autonomous marine monitoring system. The system has two advantages: it can cover larger area than other AUVs and collect more autonomous data acquisition than a fixed float meter. The scheme of data acquisition, the procedure of autonomous acquisition and layered software architecture are given. The large-area field trial is first carried out in China, which shows that marine environmental three-dimensional monitoring by AUV is practical.
    Related Articles | Metrics | Comments0
    Cited: CSCD(1)
    The data coupler design and realization in power and data mixed transmission technology based on coaxial cable
    Journal of Tropical Oceanography    2009, 28 (4): 6-11.   DOI: 10.11978/j.issn.1009-5470.2009.04.006
    Abstract1556)      PDF(pc) (7276KB)(1901)       Save
    Nowadays research device and monitoring system are power supplied by underwater lithium batteries. Underwater lithium batteries powering method has so many disadvantages that constrains the development of deep-sea scientific research. So a new mixed transmission technology based on the armored coaxial cable is proposed and finally realized. This new technology can mixed transfer direct-current high power source, real-time color image and data of both host and slave at the same time. This technology made the superposition of direct-current power source and SHDSL data signal mainly by capacitance coupling and Low-pass filtering. It adopts coaxial cable as the media for the data signal and power signal mixture transmission. Thus the goal of high-speed and long-distance transmission can be achieved.
    Related Articles | Metrics | Comments0
    Cited: CSCD(1)
    SELECTING SIMPLIFIED MODEL FOR DUAL-PROBE SEAFLOOR IN-SITU HEAT-FLOW METER

    YANG Xiao-qiu1,2,SHI Xiao-bin1,XU He-hua1,XU Xing3,LI Guan-bao4,GUO Xing-wei5,LUO Xian-hu3

    Journal of Tropical Oceanography    2009, 28 (4): 28-34.   DOI: 10.11978/j.issn.1009-5470.2009.04.028
    Abstract2150)      PDF(pc) (1525KB)(1527)       Save
    Selecting an effective and convenient simplified model for dual-probe seafloor heat-flow meter is the theoretical basis for optimizing dual-probe structure, which is very important to improve heat-flow calculation accuracy. Basing on the finite element numerical model about seafloor pulsing dual-probe, the authors analyzed in detail how the dual-probe’s heat pulse duration, heat generation rate, thermal properties, length and radius affect model errors in three line source simplified models. The selected effective and convenient simplified model is the one whose model errors are the least. The results are as follows: 1) in dual-probe heat pulse method, Pulsed Finite Line Source (PFLS) model is a more practical simplified model, in which the model errors from pulse duration and probe length can be avoided; 2) in the PFLS model, model errors from probe thermal conductivity can be neglected. In addition, model errors can recede with probe spacing increasing, probe radius decreasing and probe volume heat capacity approaching the surrounding medium. When surrounding medium temperature change can be detected and recorded effectively by the sensor probe, probe heat pulse power cannot affect model errors.
    Related Articles | Metrics | Comments0
    Assimilation of hydrographic data in the northern South China Sea based on the Cressman objective analysis
    CHEN Fei,SHI Ping,DU Yan,WANG Dong-xiao
    Journal of Tropical Oceanography    2010, 29 (4): 1-7.   DOI: 10.11978/j.issn.1009-5470.2010.04.001
    Abstract1769)      PDF(pc) (531KB)(2313)       Save

     The authors assimilate cruise data in the northern South China Sea using the Princeton Ocean Model (POM). The results show that the model assimilation improves the simulation effectively by reducing model errors, namely making the model results closer to the observations. The assimilation results, however, are not quite ideal in the regions where cruise observations are absent, indicating the method needs to be improved. This assimilation method once improved can provide re-analysis dataset for studying the South China Sea.

    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(22) CSCD(3)
    An effective method to eliminate the abnormal positioning data of USBL in the hydrothermal sulfide field investigation
    WU Xue-wen,BAO Geng-sheng,ZHANG Kai
    Journal of Tropical Oceanography    2010, 29 (4): 165-169.   DOI: 10.11978/j.issn.1009-5470.2010.04.165
    Abstract1433)      PDF(pc) (412KB)(2235)       Save

     The noise from dynamic positioning system of a vessel interferes with the data of ultra short base line (USBL) underwater positioning system in hydrothermal sulfide field investigation, while in situ decision-making and continuing research demand much better underwater positioning data. It is therefore necessary to eliminate abnormal positioning data rapidly and effectively for the existing Posidonia 6000 USBL. This study takes the USBL procedure data (x, y, z) as elimination objects, sets up (x, y, z) elimination models according to field water depth and the block angle, and uses reasonable data structure and algorithm to realize interactive elimination according to maps between (x, y, z) and time series. With the models and interactive elimination, abnormal USBL positioning data can be eliminated effectively, and much better underwater positioning data can be provided for in situ decision-making of hydrothermal sulfide investigation and continuing research.

    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(5) CSCD(1)
    OPeNDAP service based implementation of physical oceanographic data of the South China Sea
    XU Chao,LI Sha,MI Pu-chun,
    Journal of Tropical Oceanography    2010, 29 (4): 174-180.   DOI: 10.11978/j.issn.1009-5470.2010.04.174
    Abstract1684)      PDF(pc) (452KB)(3792)       Save

    OPeNDAP stands for “Open-source Project for a Network Data Access Protocol.” The OPeNDAP protocol provides a discipline-neutral means of requesting and providing data across the World Wide Web. The goal is to allow all end users to access immediately whatever data they require in a form they can use, all while using applications they already possess and are familiar with. This article introduces the available OPeNDAP servers, and elaborates on the design and building of the OPeNDAP-based Sharing Platform of Physical Oceanographic Data of the South China Sea, which uses the GDS (GrADS Data Server), Dapper and THREDDS (Thematic Realtime Environmental Distributed Data Services) data servers to realize OPeNDAP services of wind, current, wave, Argo, and tide data. It also presents the OPeNDAP Services of the Sharing Platform. With the help of OPeNDAP, the service system achieves the objective of seamless access to physical oceanographic data of the South China Sea in a highly heterogeneously distributed environment over the network.

    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(11) CSCD(4)
    Coastal sea-state monitoring system off Taiwan Island: Its establishment and data analysis
    FENG Xiang-bo,YAN Yi-xin
    Journal of Tropical Oceanography    2011, 30 (1): 35-42.   DOI: 10.11978/j.issn.1009-5470.2011.01.035
    Abstract1759)      PDF(pc) (1170KB)(3696)       Save

    Taiwan Island is at the joint of Eurasian Continent and Pacific Plate, and is always threatened by typhoons and northeasterly winds, which may cause enormous loss of human life and property every year. Therefore it is necessary to de-velop a coastal sea-state monitoring system. The COMC (Coastal Ocean Monitoring Center, National Cheng Kung University) built the Taiwan coastal sea-state monitoring system, which is modern and self-sufficient, consisting of moored buoy, pile station, tide station, coastal weather station, and radar monitoring station. To assure the data quality, Data Quality Check Pro-cedure and Standard Operation Procedure were developed by the COMC. For data analysis, some new methods are introduced to make more detailed analysis, such as EMD (empirical mode decomposition) method that is used in the analysis of storm surge water level, wavelet transform that is used to discuss the near-shore wave characteristics from X-band radar images, and data assimilation technique that is applied in wave nowcast operation. The coastal sea-state monitoring system has a great potential in providing ocean information to serve the society.

    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(2)
    Effect of surface wave breaking on upper-ocean structure revealed by assimilating sea temperature data
    ZHANG Xue-feng,HAN Gui-jun,WU Xin-rong,LI Wei,WANG Dong-xiao
    Journal of Tropical Oceanography    2011, 30 (5): 48-54.   DOI: 10.11978/j.issn.1009-5470.2011.05.048
    Abstract1636)      PDF(pc) (481KB)(2119)       Save
    Sensitivity of sea surface temperature (SST) to wave energy factor a and Charnock parameter b is discussed using Mellor-Yamada 2.5 turbulence closure model in which wave breaking is considered. The upper-ocean temperature data in summer from OWS Station Papa is assimilated to estimate a and b via a variational approach optimally. It shows that the cost function reaches minimum when a =167 and b =4.1×105. Both monthly and daily SSTs at OWS Station Papa can be successfully reconstructed with the optimal a and b , and the simulated temperature and depth of surface mixed layer are also consistent with the observation. The equation of turbulent kinetic energy is diagnosed utilizing the optimal parameters, from which the effect of wave breaking on the turbulent energy budget is revealed.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(5)
    A hybrid ensemble filter and 3D variational analysis scheme
    WU Xin-rong,HAN Gui-jun,LI Dong,LI Wei
    Journal of Tropical Oceanography    2011, 30 (6): 24-30.   DOI: 10.11978/j.issn.1009-5470.2011.06.024
    Abstract1893)      PDF(pc) (464KB)(38183)       Save
    A new hybrid data assimilation scheme based on ensemble adjustment Kalman filter (EAKF) and three-dimensional variational (3D-Var) analysis is developed. In this assimilation scheme, the perturbation of ensemble from EAKF is applied to the background field by using a transformation matrix, thus the perturbation of the analysis field can be obtained by taking advantage of a sequential filter, which will then be optimized by being combined with observations under the framework of 3D-Var. The data assimilation experiment in a perfect case is carried out by using Lorenz-63 model. The results demonstrate that the hybrid data assimilation scheme performs better than EAKF.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(6) CSCD(3)
    Power spectrum analysis of Indonesian Throughflow based on INSTANT data
    LIU Kai,SUN Zhao-bo,DU Yan
    Journal of Tropical Oceanography    2011, 30 (6): 1-9.   DOI: 10.11978/j.issn.1009-5470.2011.06.001
    Abstract1681)      PDF(pc) (695KB)(2310)       Save
    The observational data from the International Nusantara Stratification and Transport (INSTANT) Program is used to investigate the variation of the Indonesian Throughflow (ITF). Specifically, the power spectrum of the flow in surface and thermocline layers in the three major outflow passages is analyzed. The results show that the flow in the surface layer of the Lombok and Ombai straits has an obvious annual cycle. During the monsoon transition period, the flow reverses at all depths at the Lombok and Ombai straits, whereas the current reveres only below 300 m in the Timor Passage. The variations of the currents in both surface and thermocline layers are high at intraseasonal time scale. The annual cycle is prevalent in surface layer, while the semiannual cycle dominates in thermocline layer. At tidal frequencies, each strait shows that the semi-diurnal tide M2 is dominant expect for the surface layer of the Lombok Strait where the diurnal tide K1 is dominant.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(3) CSCD(1)
    Study on the hydrological characteristic parameters and flow field east of the Luzon Strait using Argo profiling floats
    HE Jian-ling,CAI Shu-qun
    Journal of Tropical Oceanography    2012, 31 (1): 18-27.   DOI: 10.11978/j.issn.1009-5470.2012.01.018
    Abstract2057)      PDF(pc) (1050KB)(2582)       Save
    The seasonal characteristics of water masses and the monthly variation of mixed layer depth are studied using Argo profiling floats in 2006 east of the Luzon Strait. The temperature-salinity relation indicates the seasonal variation of water masses is not obvious. Compare to those in summer and fall, the surface temperature is lower and the surface salinity is higher in spring and winter; they change little in deeper layers. Seasonal variation of the mixed layer depth is obvious; it is the deepest in winter with a value over 160 m, whilst it is the shallowest in summer with a value of 20 m. Based on the P -vector method, the current field in fall is calculated using Argo seasonal mean data between 2002 and 2009, Levitus data and Argo data in 2006, respectively. The wind-driven Ekman drift current is also computed. The result obtained by Argo seasonal mean data is significantly better than that by the Levitus data; the Argo data can show the structure of Kuroshio and eddies. The coupled current structure obtained by Argo data in 2006 and Ekman drift current is similar to that by the altimeter data, except that the velocity of the former is less, which may be related to the coarse and unevenly distribution of Argo profiling floats and the subsequent interpolation error. However, a three-dimensional structure of flow field could be obtained by the Argo data, whilst only the surface current field can be obtained by the altimeter data.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(4)
    Service system of the South China Sea science data products based on VisualDB
    HUO Dong-ming,LI Sha,XU Chao
    Journal of Tropical Oceanography    2012, 31 (2): 118-122.   DOI: 10.11978/j.issn.1009-5470.2012.02.016
    Abstract1729)      PDF(pc) (1483KB)(1827)       Save
    Based on MVC ( Client Middleware Server) concept and VisualDB technology, we designed and implemented the Service System of the South China Sea Science Data Products (SCSPD). Users can query, search and access data products in the SCSPD visually via Web browser. In this paper, the application of VisualDB was introduced. Software architecture design of the system , visualized process of data management and release were described in detail. In the last section , we discussed the system expansibility of the SCSPD according to the technical characteristics and application of VisualDB. The SCSPD improves data service forms of the South China Sea Ocean Database, and is instrumental in the construction of the South China Sea Data Sharing and Service System.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(4) CSCD(1)
    OBS seismic data processing and preliminary results on the hydrothermal field of the Southwest Indian Ridge
    ZHANG Jia-zheng, ZHAO Ming-hui, QIU Xue-lin, RUAN Ai-guo, LI Jia-biao, CHEN Yong-shun, AO Wei, WEI Xiao-dong
    Journal of Tropical Oceanography    2012, 31 (3): 79-89.   DOI: 10.11978/j.issn.1009-5470.2012.03.011
    Abstract1892)      PDF(pc) (1301KB)(3473)       Save
    Three-dimensional (3D) ocean bottom seismometer (OBS) survey provides a significant foundation for the deep crustal and upper mantle structure of the hydrothermal field (49°39′E) (Area A) in the Southwest Indian Ridge. OBS data processing is the basic step of obtaining the 3D seismic velocity structure. The flow steps for data processing of three types of OBS (domestic, French and Germanic OBS) were firstly introduced, containing the decompilation, cutting and seismic signal visualization. Taking the shot 2790th for example, waveforms and frequency spectrums of three types of OBSs were then analyzed, which were related to frequency band, sensor and seismograph for different OBSs. Domestic and French OBSs recorded long-periodic and short-periodic noises, and Germanic OBS only recorded short-periodic noises. However, air-gun signals were highlighted and noises were suppressed for all the OBSs after using a band-passed filter. Moreover, several seismic phases, e.g., Pg, PmP and Pn, were clearly revealed in the recorded seismic sections of three types of OBSs (OBS04, OBS08 and OBS23) along the profile X1X2. These phases will provide a strong data base for 3D tomography for studying Area A.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(16) CSCD(9)
    Design of gun controlling chronometer and its application in gathering and processing OBS data
    HU Jia-fu, XU Hua-ning, QIU Xue-in, PENG Zhao-xu, WU Zhong-liang
    Journal of Tropical Oceanography    2012, 31 (3): 97-102.   DOI: 10.11978/j.issn.1009-5470.2012.03.013
    Abstract1611)      PDF(pc) (403KB)(1810)       Save
    In order to obtain raw and accurate data processing section of ocean bottom seismograph (OBS) in marine geophysical exploration, negative effects of positional time and positional accuracy in acquisition and processing must be eliminated. Through analyzing the effects of the accuracy of positional time in OBS data processing and analyzing the timing error sources, we developed a gun controlling chronograph to improve positional precision and to eliminate conventional timing error; the accuracy can reach 0.01 ms, to realize high accuracy of navigation shotpoint time positioning and timing and to ensure the accuracy in OBS data acquisition. The results of stability testing and production testing show the time fixing capacity of chronograph can meet the demands of OBS multi-component acquisition perfectly, as well as in other marine geophysical prospecting areas that need high accuracy timing.
    Reference | Related Articles | Metrics | Comments0
    Cited: CSCD(2)
    A method for SST retrieval from ASTER image without using in-situ data
    ZHENG Shan-shan, CHEN Chu-qun
    Journal of Tropical Oceanography    2013, 32 (5): 9-14.   DOI: 10.11978/j.issn.1009-5470.2013.05.002
    Abstract683)      PDF(pc) (618KB)(1673)       Save
    The moderate resolution atmospheric radiance and transmission (MODTRAN), with the input parameters obtained from Terra/MODIS (moderate resolution imaging spectroradiometer), was used to calculate the atmospheric effect parameters, including atmospheric transmittance, upward radiance and downward radiance. Combined with the sea surface emissivity provided by the Jet Propulsion Laboratory (JPL) and spectral response functions for five bands of advanced spaceborne thermal emission and reflection radiometer (ASTER) sensor, the sea surface temperatures (SST) were solved from radiative transfer equations pixel by pixel for each band. If the difference between any two bands’ SSTs for the same pixel is less than 0.5K, the average of five bands’ SSTs of the pixel was taken as true SST, which was then used to derive the undetermined coefficients of Split-Window algorithm. Finally, the Split-Window algorithm was applied for the SST retrieval. The results showed the algorithm has good accuracy. The SST values retrieved from ASTER data acquired on October 20, 2007 were compared to the MODIS SST, which gives the mean deviation of 0.35℃ and the root-mean-squared error (RMSE) of 0.49℃. The same procedure was repeated for ASTER data acquired on May 15, 2008, which gives the mean deviation of 0.38℃ and RMSE of 0.52℃.
    Reference | Related Articles | Metrics | Comments0
    Assessment of Aquarius/SAC-D salinity data accuracy in the South China Sea
    WANG Xin-xin, YANG Jian-hong, ZHAO Dong-zhi, WANG Xiang, SUN Guang-lun
    Journal of Tropical Oceanography    2013, 32 (5): 23-28.   DOI: 10.11978/j.issn.1009-5470.2013.05.004
    Abstract762)      PDF(pc) (505KB)(1858)       Save
    This study assesses the accuracy of Aquarius/SAC-D satellite sea surface salinity (SSS) data in the South China Sea using Argo buoy data, and analyzes the influencing factors. The results indicate that the linear relationship of co-located data is not significant. The SSS inversion accuracy in the South China Sea and northeastern waters is 0.62‰ and 0.70‰, respectively. Located at low latitude, the sea surface temperature (SST) in the South China Sea is high, which has a small effect on the accuracy. The factors that influence the SSS accuracy may be the strong breeze, rainfall and land radio frequency interference (RFI), etc. The results show that the SSS retrieval error increases with wind speed when the wind speed is greater than 7 m·s-1, and that the error has a clear ascendant trend. Meanwhile, the South China Sea is seriously contaminated by the land RFI. Even if the Aquarius/SAC-D SSS product has corrected the land RFI in its new Version 1.3. The RFI is not eliminated, and may still have an influence on the accuracy.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(3) CSCD(7)
    Single ping filtering of multi-beam echo sounder data based on dynamic clustering
    CHEN Xiao-long, PANG Yong-jie, LI Ye
    Journal of Tropical Oceanography    2013, 32 (5): 73-78.   DOI: 10.11978/j.issn.1009-5470.2013.05.010
    Abstract708)      PDF(pc) (540KB)(10676)       Save
    For the data characteristics of interferometric multi-beam echo sounder (MBES), a single ping filtering method of MBES based on dynamic clustering is proposed. Considering the continuity of real terrain, the problem of outlier detection is transformed into clustering of real terrain data. Through continuous clustering of real terrain data, the outliers in data are eliminated. For the large data size in the process of clustering, dynamic clustering is adopted after partitioning clustering sets. Simultaneously, a trend adjusted factor is introduced for the feature domain selection, which is helpful for the decision of clustering direction. At last, the improved k-means method is utilized for output of clustering object. The results from processing sea test data of GeoSwath MBES show that the algorithm has good adaptability for different terrain characteristics, and is simple for implementation, which can be used for real-time filtering and post-processing of MBES data.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(3)
    Analysis of horizontal stirring in the South China Sea derived from satellite altimeter data
    LI Wei-jie, ZHAN Hai-gang
    Journal of Tropical Oceanography    2014, 33 (2): 10-16.   DOI: 10.11978/j.issn.1009-5470.2014.02.002
    Abstract574)      PDF(pc) (555KB)(1839)       Save
    Stirring is an important part of mixing, which can be quantified using Finite Time Lyapunov Exponents (FTLE) based on Lagrangian view. In this paper, we calculated the FTLE of surface ocean derived from satellite altimeter from 2002 to 2011, and then analyzed spatial and temporal variation of horizontal stirring in the South China Sea (SCS). Results show that FTLE in the SCS is not uniform, with high values southeast of Vietnam indicating strong stirring, and low values in the northwest and southeast of the SCS. A slowly increasing trend of stirring in the SCS is observed during the 10 year period. FTLE also displays a seasonal fluctuation, strong in summer but weak in winter. Furthermore, we found that FTLE has a similar spatial distribution with Euler-based eddy kinetic energy (EKE) and strain rate, with high and low values of these three quantities locating roughly in the same areas. A comparison with Okubo-Weiss parameter reveals a strong relationship between vortices and FTLE ridges, referred to as Lagrangian Coherent Structures (LCS). Low values of FTLE are mainly present inside rotation-dominated vortices, while high values occur in strain-dominated regions surrounding the vortices.
    Reference | Related Articles | Metrics | Comments0
    High-resolution processing methods for multi-channel reflection seismic data of Lile sea area in the southern South China Sea
    ZHENG Hong-bo, YAN Pin, WANG Yan-lin
    Journal of Tropical Oceanography    2014, 33 (5): 67-73.   DOI: 10.11978/j.issn.1009-5470.2014.05.009
    Abstract490)      PDF(pc) (741KB)(1514)       Save
    Lile sea area of the southern South China Sea has become an important prospective area of oil and gas exploration because of its abundant resources. At present, the exploration level of Lile sea area is low, and there are only two-dimensional seismic data of a few survey lines. Due to complex terrains and large changes of water depth, multiform interferential waves can be commonly distinguished from these seismic data. Moreover, the trace number of shot gather is small, and the S/N ration of data is low. Above factors are of disadvantage to high-resolution processing of seismic data. According to the characteristics of seismic data in the area, various means have been used for true amplitude recovery and abnormal amplitude suppression in the pretreatment. Series deconvolution methods have been used to enhance the resolution of the seismic data; τ-p domain predictive deconvolution, velocity filtering and inner muting have been adopted for multiples suppression based on the types of multiples. From the result of processing, it can be found that the energy of shallow, middle and deep layers is proportioned. Interferential waves such as multiples have been well suppressed, and the S/N ratio and resolution of seismic data have been improved. High-resolution seismic stacked profiles have been achieved finally.
    Reference | Related Articles | Metrics | Comments0
    Cited: CSCD(1)
    The selection of optimal inversion parameters for first-arrival seismic tomography: An application to 3D seismic data from the central sub-basin of the South China Sea
    WANG Jian, ZHAO Ming-hui, HE En-yuan, ZHANG Jia-zheng, QIU Xue-lin
    Journal of Tropical Oceanography    2014, 33 (5): 74-83.   DOI: 10.11978/j.issn.1009-5470.2014.05.010
    Abstract678)      PDF(pc) (943KB)(1972)       Save
    First arrival seismic tomography (FAST) is one of the most widely used seismic tomography tools to achieve complicated three-dimensional (3D) deep crustal structure. The selection of optimal inversion parameters for FAST is a key to obtain a reasonable velocity model effectively. Based on the 3D seismic survey data collected from the central sub-basin of the South China Sea (SCS), the selection process of inversion parameters was illustrated in detail in this paper, using the control variate method, namely, selecting one parameter while fixing the other parameters, and then selecting the combination of all parameters comprehensively. The result showed that the combination of parameters (damping parameter λ=2, smoothness weighting parameter sz=1, inversion number I=4) was an assembly of optimal inversion parameters for the 3D seismic structure of the central sub-basin of the SCS. The preferred preliminary velocity structure acquired by this combination indicated that the central sub-basin could be classified as a typical slow-spreading oceanic crust. The research of choosing inversion parameters not only lays a foundation for further modeling of detailed 3D seismic structure of the Zhenbei-Huangyan seamount chain but also provides reference and experience for the application of FAST software in other potential areas.
    Reference | Related Articles | Metrics | Comments0
    Preliminary results of the South Yellow Sea OBS 2013 onshore-offshore joint deep seismic survey
    QI Jiang-hao, ZHANG Xun-hua, WU Zhi-qiang, QIU Xue-lin, ZHAO Ming-hui, XIA Shao-hong, GUO Xing-wei, HAO Tian-yao, ZHENG Yan-peng, FANG Nian-qiao
    Journal of Tropical Oceanography    2015, 34 (2): 76-84.   DOI: 10.11978/j.issn.1009-5470.2015.02.010
    Abstract513)      PDF(pc) (7844KB)(1601)       Save
    In order to study the deep tectonic characteristics along the line of Bohai Sea-Shandong Peninsula-South Yellow Sea, using marine air gun source and land explosive source detection, the Bohai Sea-Shandong Peninsula-South Yellow Sea onshore-offshore joint deep seismic survey profile was carried out in 2013. The onshore-offshore deep seismic profile comprises two ocean bottom seismometer (OBS) seismic lines in the Bohai Sea and the South Yellow Sea and one onshore seismic line. This is the first OBS seismic line in the South Yellow Sea. After data preprocessing of South Yellow Sea OBS, including data decoding and data cutting, etc., the results show that the OBS recording quality is good. We can not only identify the seismic phases such as Ps, Pg and PmP but also observe the P-wave seismic phases from the Qianliyan uplift zone for the first time, which means the data processing is feasible. Combined with geological and geophysical data, a preliminary analysis of the phase character in different structural units of the South Yellow Sea was carried out, laying a good foundation for future simulation and interpretation of crust velocity structure.
    Related Articles | Metrics | Comments0
    Cited: Baidu(5) CSCD(4)
    Seasonal variation of the water exchange between the Bay of Bengal and the equatorial eastern Indian Ocean
    XUAN Li-li, QIU Yun, XU Jin-dian, Li Zi-qiang
    Journal of Tropical Oceanography    2015, 34 (6): 26-34.   DOI: 10.11978/2015012
    Abstract673)      PDF(pc) (5069KB)(1604)       Save
    Based on the simple ocean data assimilation (SODA) reanalysis and satellite observations, we analyzed the seasonal variation of the meridional salt exchange between the Bay of Bengal (BOB) and the equatorial eastern Indian Ocean (EEIO). We estimated the annual-mean freshwater transport along the 6°N section at the mouth of the BOB. Results showed that the salt exchange between BOB and EEIO is dominated by the currents, and its direction is almost opposite between the east and west sides at the bay mouth. During the southwest monsoon (northeast monsoon), the salt flux is northward (southward) in the west while it is southward (northward) in the east of the bay mouth. Furthermore, the freshwater flows out of (into) the bay during April to October (November to the following March). The freshwater transport from the BOB to the EEIO happens in the whole depth. The annual-mean freshwater transport is 1.0×105m3·s-1.
    Reference | Related Articles | Metrics | Comments0
    Evaluation of SMOS sea surface salinity data in the equatorial Pacific and its correction using neural network
    ZENG Zhi, CHEN Xue-en, TANG Sheng-quan, WANG Wei-dong, GAO Rong-lu, YUAN Nan
    Journal of Tropical Oceanography    2015, 34 (6): 35-41.   DOI: 10.11978/2014140
    Abstract913)      PDF(pc) (2954KB)(3942)       Save
    In this paper, sea surface salinity data of the equatorial Pacific Ocean in 2011~2012, acquired by the Soil Moisture and Ocean Salinity (SMOS) satellite, was processed for quality control and then analyzed for the first time in terms of dynamic process factors that may impact salinity retrieval. The neural network method was introduced to improve the quality-controlled salinity data of the same time period. It was found that precipitation and surface wave induced by precipitation can increase salinity error substantially in a negative trend. Sea surface roughness caused by wind also increased salinity errors. There was a weak positive correlation between wind speed and salinity error. Changes in sea surface temperature had little effect on salinity retrieval. Considering rainfall, wind speed and other major marine dynamic processes, the neural network method was used to revise sea surface salinity data of the equatorial Pacific in December 2011. The results showed that the RMS (root mean square) of salinity reduced from 0.383 7 to 0.244 1. It was found that not only was the salinity error caused by precipitation and other dynamic processes eliminated, but also the high salinity tongue in the equatorial Pacific was revealed, which the Level-3 data failed to.
    Reference | Related Articles | Metrics | Comments0
    On South China Sea marine data collection and management
    XU Xiao-lu, LI Sha, XU Chao
    Journal of Tropical Oceanography    2015, 34 (6): 42-48.   DOI: 10.11978/2015023
    Abstract530)      PDF(pc) (324KB)(1663)       Save
    According to the types of South China Sea marine datasets, especially the cruise data format, based on the marine data specifications at home and abroad, and on the references of a large number of relevant specifications, we designed “Collection and Management Guide of the South China Sea Data”, which is suitable for the South China Sea Ocean Database. It includes six data management specifications. In terms of data collection, the guide regulates data factor, data information, data classification, and data format, in terms of data management and guide proposes of data format conversion specification. This achieves various marine data collection and management effectively, promotes the specification system of the South China Sea marine data and improves the sharing of marine data and application services.
    Reference | Related Articles | Metrics | Comments0
    Study on data sharing for scientific investigation in the South China Sea based on cloud computing
    HE Hong-qian, LI Sha, XU Chao
    Journal of Tropical Oceanography    2015, 34 (6): 49-56.   DOI: 10.11978/2015007
    Abstract519)      PDF(pc) (5789KB)(1158)       Save
    With the emergence of cloud computing, great changes have taken place in data sharing. Cloud computing is considered to be a scientific data sharing platform. Through the network, software and hardware based on resource intensive operations will improve the stability and scalability of the server, and the efficiency for data sharing. This paper builds scientific investigation data sharing platform of cloud computing, using VDB3.0 based on the enterprise cloud computing platforms (ECCP). Integrated with phpMyAdmin and other tools, the unified management of heterogeneous data sources is realized, transforming data into flexible services. This study improved the security of data storage, organization and management efficiency.
    Reference | Related Articles | Metrics | Comments0
    Cited: Baidu(1) CSCD(1)
    A method for merging multi-source global oceanic precipitation information
    SUI Yuzheng, CUI Linli, SHI Jun, LI Shujuan
    Journal of Tropical Oceanography    2016, 35 (2): 50-56.   DOI: 10.11978/2015037
    Abstract562)      PDF(pc) (542KB)(772)       Save
    To obtain a continuous high-resolution oceanic precipitation data, eight different oceanic precipitation products, including COADS, ECMWF, NCEP, GPCP_GPI, SSM/I_EMISS, SSM/I_SCATT, TRMM_PR, and TOPEX-TMR, were merged using an optimal weighted coefficient method to produce a new merged precipitation product. The product was obtained based on the spatial-temporal characteristics of these precipitation products and the principle of data merging. The merged product was validated using actual precipitation data from nine coastal rain gauge stations and the eight products. The merged precipitation product is better than the other data sets in terms of accuracy, and can compensate for the limitation of other multi-source precipitation products, suggesting that the optimal weighted coefficient method is an important scheme for reducing information redundancy and increasing the complementation of multi-source oceanic precipitation data sets.
    Reference | Related Articles | Metrics | Comments0
    Cited: CSCD(1)
    Study on characteristics of mean flow and tidal currents in the southwestern Taiwan Strait based on shipboard ADCP observations in summertime
    SHEN Junqiang, SUN Haowei, PAN Aijun, Qiu Yun
    Journal of Tropical Oceanography    2016, 35 (3): 11-19.   DOI: 10.11978/2015100
    Abstract766)      PDF(pc) (603KB)(1291)       Save

    In this study, we conducted barotropic detiding of the summertime shipboard ADCP (SADCP) dataset in the southern Taiwan Strait (TWS) from June to September during 2004-2013, employing the widely used spatiotemporal fitting by the least squares method (STF-LSM). The results show that the mean flow derived from STF-LSM and that derived from averaged vectors by dataset gridding both flowed northeastward. Moreover, these two mean flows had similar spatial distribution patterns of strong and weak flows, but their maximum velocities were slightly different: 0.46 and 0.34 m·s-1 for the former and the latter, respectively. Besides, the strong currents (about 0.3 m·s-1) were characterized by the narrow mainstream confined around the depth of 30 m off the sea at Dongshan and Longhai as well as the Taiwan Bank (TWB) with drastic topographic change, whereas the weak currents (less than 0.1 m·s-1) were mainly distributed in the central TWB. Estimation of the volume transport based on the above mentioned mean flows revealed similar results, up to (0.71±0.24) ×106 m3·s-1. The strong M2 tidal currents derived from SADCP were near the TWB and extended to the offshore of Dongshan, with a maximum M2 current amplitude as large as ~0.64 m·s-1, which was located in the TWB. The cotidal chart for M2 currents demonstrates the characteristics of progressive wave, which was delayed successively from the southwest to the northeast along the direction of the tidal wave as the wave propagated (about 2 h). Besides, there was a boundary line along northwestward to southeastward direction with ellipticity equal to zero at the offshore of Dongshan. The M2 currents rotated counterclockwise in the southern region of this boundary line and clockwise in the northern region.

    Reference | Related Articles | Metrics | Comments0
    Cited: CSCD(2)
    The dynamic characteristics of deep meridional overturning circulation in the Indian Ocean based on six reanalysis datasets
    HUANG Xumei, WANG Weiqiang, LIU Hailong
    Journal of Tropical Oceanography    2016, 35 (4): 11-20.   DOI: 10.11978/2015126
    Abstract572)      PDF(pc) (756KB)(1431)       Save
    The dynamic characteristics of time-mean meridional overturning circulation in the Indian Ocean was examined using six reanalysis datasets. The results showed consistent time-mean features of the deep meridional overturning circulation, which is an anticlockwise overturning cell with inflows in the bottom and deep layers and outflows in the intermediate and upper layers. Dynamic decomposition of meridional overturning circulation was applied to examine the similarities and differences of every dynamic component. The structure of Ekman component is an anticlockwise overturning cell in the South Indian Ocean with maximum strength at ~10°S. In the region south of 10°S, geostrophic and external components show clockwise and anticlockwise overturning cells, respectively, they both reach maximum strengths at ~27°S. Based on different products of heat and momentum fluxes used, the dynamic components resulted from the six datasets show some inconsistent features as follows. The overall structures of Ekman component are similar since the wind fields of the six datasets have few differences. The discrepancies of the geostrophic component in the six datasets are due to the strength of the baroclinic flows in the interior ocean and the structure of the western boundary current: the greater the baroclinic flows in the interior ocean, the stronger the strength of the geostrophic component; the wider the western boundary current, the greater impact on the baroclinic flows in the interior ocean, and then on the strength of the geostrophic component. The strength of the external component is affected by the intensity of the western boundary current: the greater the western boundary current, the stronger the strength of the external component.
    Reference | Related Articles | Metrics | Comments0
    The inversion of multiple-phase SSTs based on the MODIS data: a case study on the southwest coastal waters of Hainan Island
    Tiantian GUO, Shengbo CHEN, Tianqi LU
    Journal of Tropical Oceanography    2017, 36 (1): 9-14.   DOI: 10.11978/2016032
    Abstract667)   HTML152)    PDF(pc) (386KB)(1035)       Save

    By regarding the moderate resolution imaging spectroradiometer (MODIS) remote sensing data as data sources and the southwest coastal waters of Hainan Island as the study area, the improved spilt-window algorithm is used to inverse the SST of the study area from 2005 to 2014. To verify the retrieval accuracy of the SST, we calculate the correlation coefficient between the inversion and measured results using the measured values of 12 observation points; the coefficient is 0.9. Based on the inversion results of SST, the data of four seasons in a year and a decade are analyzed to show the spatial and temporal variations of SST distribution, respectively. Results show that using the MODIS multi-channel improved spilt-window algorithm we can inverse Hainan Island offshore SST accurately. The spatial and temporal variations of SST distribution thus obtained can provide important reference values for marine fishery, change of marine environment and meteorological monitoring.

    Table and Figures | Reference | Related Articles | Metrics | Comments0