南海东北部的断裂分布及其构造格局研究   总被引：3，自引：0，他引：3  

陈冰  王家林  钟慧智  陈焕疆  郝沪军  李平鲁 《热带海洋学报》2005,24(2):42-51

通过对南海东北部重磁异常的分析和处理，结合珠江口盆地、潮汕坳陷等地区的综合地质地球物理研究成果，根据研究区的重磁异常特征划分了4个异常区。应用地球物理数据处理方法，推断了该区的主要断裂35条，其主要走向为NW、NE、NEE向及S-N向4组。综合各方面研究成果在该区划分了7个构造单元。依据地震剖面、物性资料和重磁资料的分析，对南海东北部地区中生界的地层标定、构造与结构特征有了新的认识，研究了该地区前第三系基底和中生界的分布，并对南海东北部构造演化进行了探讨。  相似文献   

Multi-decadal synthesis of benthic–pelagic coupling in the western arctic: Role of cross-shelf advective processes     

Kenneth H. Dunton  Jonathan L. Goodall  Susan V. Schonberg  Jacqueline M. Grebmeier  David R. Maidment 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3462

Using geographic information systems (GIS) software and geostatistical techniques, we utilized three decades of water-column chlorophyll a data to examine the relative importance of autochthonous versus allochthonous sources of reduced carbon to benthic communities that occur from the northern Bering to the eastern Beaufort Sea shelf. Spatial trend analyses revealed areas of high benthic biomass (>300 g m⁻²) and chlorophyll (>150 mg m⁻²) on both the southern and northern Chukchi shelf; both areas are known as depositional centers for reduced organic matter that originates on the Bering Sea shelf and is advected northward in Anadyr and Bering shelf water masses. We found a significant correlation between biomass and chlorophyll a in the Chukchi Sea, reflective of the strong benthic–pelagic coupling in a system that is utilized heavily by benthic-feeding marine mammals. In contrast, there was no significant correlation between biomass and chlorophyll in the Beaufort Sea, which by comparison, is considerably less productive (biomass and chlorophyll, <75 g m⁻² and <50 mg m⁻², respectively). One notable exception is an area of relatively high biomass (50–100 g m⁻²) and chlorophyll (80 mg m⁻²) near Barter Island in the eastern Beaufort Sea. Compared to other adjacent areas in the Beaufort Sea, the chlorophyll values in the vicinity of Barter Island were considerably higher and likely reflect a long-hypothesized upwelling in that area and close coupling between the benthos and autochthonous production. In the Bering Sea, a drop in benthic biomass in 1994 compared with previous measurements (1974–1993) may support earlier observations that document a decline in biomass that began between the 1980s and 1990s in the Chirikov Basin and south of St. Lawrence Island. The results of this study indicate that the benthos is an excellent long-term indicator of both local and physical advective processes. In addition, this work provides further evidence that secondary production on arctic shelves can be significantly augmented by reduced carbon advected from highly productive adjacent shelves.  相似文献   

Using the Mellor–Yamada mixing scheme in seasonally ice-covered seas—Corrigendum to: Parameterization of vertical mixing in the Weddell Sea [Ocean Modelling 6 (2004) 83–100]     

Ralph Timmermann  Martin Losch 《Ocean Modelling》2005,10(3-4):369-372

A coding error in the s-Coordinate Primitive Equation Model (SPEM) has led to misleading statements about the behaviour of the Mellor–Yamada level 2 parameterization of vertical mixing. It has been claimed that the scheme removes static instability only very slowly and preserves statically unstable stratifications for an unrealistic long time. This note corrects this statement by demonstrating that the Mellor–Yamada mixing scheme, if implemented correctly, tends to overestimate rather than underestimate vertical mixing in seasonally ice-covered seas. Similar to other mixing schemes with the same behaviour, this leads to spurious open ocean deep convection, an unrealistic homogenization of the water column, and a significant reduction of sea ice volume.  相似文献   

Vertical and seasonal distribution of eight Clausocalanus species (Copepoda: Calanoida) in oligotrophic waters   总被引：1，自引：0，他引：1  

Peralba  Aurea; Mazzocchi  Maria Grazia 《ICES Journal of Marine Science》2004,61(4):645-653

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Variations in wave direction estimated using first and second order Fourier coefficients     

V. Sanil Kumar  N. M. Anand 《Ocean Engineering》2004,31(17-18):2105-2119

In most design applications such as alignment of the berthing structure and breakwater alignment, it becomes necessary to determine the direction of design wave. There are two different approaches to determine wave direction. One involves the use of first order Fourier coefficients (mean wave direction) while the other uses second order Fourier coefficients (principal wave direction). Both the average wave direction over the entire frequency range (0.03–0.58 Hz) and the direction corresponding to the peak frequency are used in practice. In the present study, comparison is made on wave directions estimated based on first and second order Fourier coefficients using data collected at four locations in the west and east coasts of India. Study shows that at all locations, the mean and principal wave directions for frequencies ranging from 0.07 to 0.25 Hz (±0.5 times peak frequency) co-vary with a correlation coefficient of 0.99 but at lower and higher frequencies, difference between the parameters is large. Average difference between the mean wave direction at peak frequency and the average over the frequency related to spectral energy more than 20% of maximum value is less, around 13°. Study shows that average difference in the sea and swell directions is around 39°.  相似文献   

关于南海暖水季节和年际变化的研究   总被引：1，自引：3，他引：1  

王启 《中国海洋大学学报(自然科学版)》2003,33(6):821-824

阐述了研究南海暖水的意义 ,综述了关于南海暖水的现状 ,提出了关于南海暖水季节和年际变化方面应该研究的问题  相似文献   

南海南部粉红色 Globigerinoides ruber 冰期旋回及影响因素     

徐建  翦知湣 《海洋地质与第四纪地质》2003,23(4):59-64

对南海南部ODP1143站氧同位素11-5e期大约2ka分辨率的粉红色Globigerinoides ruber进行分析,发现其冰期／间冰期旋回与代表全球冰量的底栖有孔虫氧同位素(δ^18O)的变化相反,即在间冰期时含量低,而冰期时高,与其他海区的记录相反。海水表层温度和温跃层深度转换函数结果以及碎壳率的变化显示,在一定的温度背景下,温跃层深度的变化可能是控制粉红色G．ruber冰期旋回的主要因素,而这段时期南海南部溶解作用的影响则不明显。  相似文献   

Competition within the marine microalgae over the polar dark period in the Greenland Sea of high Arctic   总被引：2，自引：0，他引：2  

Zhang Qing  Rolf Gradinger  Zhou Qingsong 《海洋学报(英文版)》2003,22(2):233-242

Abstract-With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected fordark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstern in October 1995. After a dark period of 161 days, species dominance in the algal assemblagehave changed from initially pennate diatoms to small phytoflagellates (<20μm). Over the entire darkperiod, the mean algal growth rate was-0.01 d~(-1). Nearly all diatom species had negative growthrates, while phytoflagellate abundance increased. Resting spore formation during the dark period was ob-served in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We as-sume that facultative heterotrophy and energy storage are the main processes enabling survival during thedark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth withindays. Phytoffa  相似文献   

A method to estimate the forces exerted by internal solitons on cylindrical piles   总被引：1，自引：0，他引：1  

Shuqun Cai  Xiaomin Long  Zijun Gan 《Ocean Engineering》2003,30(5):673-689

Internal soliton is the large amplitude wave existing in the pycnocline, induced by internal tide in the condition of special bottom topography. During its propagation process, the induced disturbance can bring about strong convergence of sea water and sudden strong current (wave-induced-current), which can cause severe threat to the ocean engineering structures, such as oil drilling platform and pipeline. In this paper, Morison’s empirical method, modal separation and regression analyses are introduced to estimate the forces and torques exerted by internal soliton on cylindrical piles. As an example, a limited set of observational data recording a passage of the internal soliton near Dongsha Islands is used to estimate the horizontal velocity and its acceleration in a vertical section for computing the force and torque on a supposed pile, and the estimation results are reasonable. It is shown that, the higher number of the modes retained in the calculation, the better the estimation of velocity profile fits the observational one. A better overall approximation to the real solution can be reached if there are more observational current data acquired in a whole vertical profile.  相似文献   

基于EOF分析对南海西北海域水体光谱特性的研究   总被引：1，自引：0，他引：1  

付东洋  黄宇业  刘大召  廖珊  余果  张小龙 《海洋学报(英文版)》2020,39(7):107-114

This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.  相似文献