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Fronts and transport of suspended matter in the hangzhou Bay

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Acta Oceanologica Sinica 1993年第1期12卷 1-15页

作者： su jilan wang kangshan and Li Yan second institute of oceanography, state oceanic administration, hangzhou 310012, china second institute of oceanography State Oceanic Administration Hangzhou 310012 China China

A persistent, year-round NE-SW front is found to exist inside the hangzhou Bay. This front is actually the merging of the secondary Changjiang plume front from the bay mouth and the Qiantang plume front from the upstream side of the bay. During neap tides low runoff periods these two plumes can readily be identified. Our findings suggest that suspended matter is transported into the bay through the north end by the secondary Changjiang plume. The front inside the bay acts the part of concentrating suspended matter, and also plays an important role in both the fine-grained sediment and heavy metal distributions in this sedimentary basin.

关键词： Fronts and transport of suspended matter in the hangzhou Bay

A two-layers model for the summer circulation of the East china Sea

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Acta Oceanologica Sinica 1994年第3期13卷 325-344页

作者： Liang Xiangsan and su jilan(second institute of oceanography, state oceanic administration, hangzhou 310012, china)

A two-layers numerical model is developed to study the dynamical structures and the formation mechanisms of the summer shelf circulation and the Kuroshio system in the East china Sea (ECS). On the whole, themain features of this region are highly correlated and dynamically stable. The Kuroshio northeast of Taiwan Islandalways intrudes into the shelf, and manifests itself chiefly in the lower layer. The horizontal advection and bottomfriction are the triggering mechanisms for this ageostrophic intrusion current, while the topographic beta-effectmake it intensified towards the northern edge of Taiwan island. After intruding into the shelf, most of the lowerlayer Kuroshio water turns anticyclonically, forming the outer branch of the lower-layer Taiwan Warm Current(TWC). Whether its inner partner can form depends upon the ratio of the upper-to the lower-layer speeds of theKuroshio inflow, and the northward extending of the upper-layer strait warm water. The upper-layer TWC resultsfrom the Taiwan Strait inflow, and a part of it branches out in the open sea off Wenzhou. In this paper,we alsopoint out that the cold-core water mass northeast of Taiwan Island is, in fact,the manifestation of the lower-layerintruslve loop, and the interaction between it and the upper-layer TWC leads to the formation of the well-knownwarm-core gyre. Besides,a preliminary study is also made on the frontal eddy north of Diaoyu Island.

关键词： Kuroshio intrusion Taiwan Warm Current (TWC) cold- (warm-) core center

Diagnostic calculation of the upper-layer circulation in the South china Sea during the winter of 1998

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Acta Oceanologica Sinica 2004年第2期23卷 187-199页

作者： YUANYaochu BUXianwei LIAOGuanghong LOURuyun sujilan wangkangshan secondinstituteofoceanography StateOceanicAdministrationHangzhou310012China

On the basis of hydrographic data obtained in November 28 to December 27, 1998 cruise, the calculation of the circulation in the South china Sea (SCS) is made by using the P-vector method, in combination with SSH data from TOPEX/ERS-2 analysis. For study of the dynamical mechanism, which causes the pattern of winter circulation in the SCS, the diagnostic model (Yuan et al., 1982; Yuan and su, 1992) is used to simulate numerically the winter circulation in the SCS. The following results have been obtained. (1) The main characteristics of the circulation systems in the central SCS are as follows: A coastal southward jet in winter is present at the western boundary near the coast of Vietnam; there is a stronger cyclonic circulation with a larger horizontal scale east of this coastal southward jet and west of 114°E; there is a weaker anti-cyclonic circulation in the central part of eastern SCS; there is a stronger and northeastward flow opposing the northeasterly monsoon between above a stronger cyclonic circulation and a weaker anti-cyclonic circulation. (2) The circulation systems in the northern SCS are as follows: 1) There is a cyclonic circulation system northwest of Luzon, and it has three centers of the cold water; 2) There is an anti-cyclonic eddy. Its center is located near(20°N, 116°40' E); 3)There is a warm and anti-cyclonic circulation south of Hainan Island; 4) There is a northeastward flow, the South china Sea Warm Current, in winter off Guangdong coast in the northern SCS. (3) In the southern SCS there is an anti-cyclonic circulation, and also there is a smaller scale cold water and cyclonic eddy. (4) The above pattern of winter circulation in the SCS agrees qualitatively with the horizontal distribution of temperature at 200 m level. (5) The dynamical mechanism which produces the above basic pattern of winter circulation is because of the following two causes: 1) The joint effect of the baroclinity and relief (JEBAR) is an essential dynamical cause; 2) T

关键词： SCS upper-layer circulation in winter of 1998 JEBAR interaction between the wind stress and bottom topographic SSH data from TOPEX/ERS-2

The formation and evolution of the East china Sea winter dense water

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Acta Oceanologica Sinica 1991年第4期10卷 525-538页

作者： Pan Yuqiu, su jilan Xu Duanrong second institute of oceanography,state oceanic administration,hangzhou 310012,china

On the basis of the historical profile observations and the recent Kuroshio observations,the yearly formation,development and decay of the high density water found between 50 to 100 m isobath over the middle and southern East china Sea continental shelf are anyalysed. The formation of this high density water occurs between November and March of the following year. A possible reason for it is that as the mixed water between the coastal water and the outer sea water transports northward by the Taiwan Warm Current, its density increases by surface cooling. It also mixes with the neighbouring lower density water masses. The transportation and decay of the high density water through April to July are also descussed. They can be ascribed to the seasonal surface layer warming and the fast development of Taiwan Warm Current. The high density water disappears in August.

关键词： In The formation and evolution of the East china Sea winter dense water

Calculation of circulation in the South china Sea during summer of 2000 by the modified inverse method

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Acta Oceanologica Sinica 2005年第1期24卷 14-30页

作者： YUANYaochu LIUYonggang LIAOGuanghong LOURuyun sujilan wangkangshan secondinstituteofoceanography StateOceanicAdministrationHangzhou310012China／／KeyLaboratoryofOceanDynamicProcessesandSatelliteOceanographyofStateOceanicAdministrationHangzhou310012China CollegeofMarineScience UniversityofSouthFloridaUSA

On the basis of hydrographic data obtained in August 2000 cruise, the circulation in the South china Sea (SCS) is computed by the modified inverse method in combination with SSH data from TOPEX/ERS-2 analysis. For study of the dynamical mechanism, which causes the pattern of summer circulation in the SCS, the diagnostic model (Yuan et al. 1982. Acta Oceanologica Sinica,4(1):1-11; Yuan and su. 1992. Numerical Computation of Physical oceanography.474-542) is used to simulate numerically the summer circulation in the SCS. The following results have been obtained. (1) The central and southwestern SCSs are dominated mainly by anticy-clonic circulation systems. They are mainly as follows. 1) There is strong anticyclonic eddy southeast of Vietnam (W1). Its horizontal scale is about 300 km, and it extends vertically from the surface to the about 1 000 m level. 2) There are a warm eddy W2 southeast of Zhongsha Islands and the anticyclonic circulation system W3 west off the Luzon Island. 3) There is a stronger cyclonic eddy C1 between the anticyclonic eddies W1 and W2.4) A strong northward coastal jet is present near the coast of Vietnam, and separates from the coast of Vietnam at about 12° N to the northeast.(2)The northern SCS is dominated mainly by a cyclonic circulation system. There is a cyclonic circulation system near and north of Section N2. (3) The southeastern SCS is dominated mainly by the cyclonic circulation system. (4) Comparing the results of circulation in the SCS during the summer of 2000 with those during the summer of 1998, it is found that they agree qualitatively, but there is the some difference between them in *** shows that the circulation in the SCS has obviously seasonal feature. (5) The dynamical mechanism which products the basic pattern of summer circulation is because the following two reasons: 1) the joint effect of the baroclinity and relief (JEBAR) is essential dynamical cause; and 2) it is next important dynamical cause that the int

关键词： SCS circulation in the summer of 2000,JEBAR interaction between the wind stress and bottom topography SSH data from TOPEX/ERS-2 modified inverse method

A numerical study for the coastal upwelling and the coastal front off Zhejiang coast

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Acta Oceanologica Sinica 1990年第4期9卷 499-512页

作者： Liu Xianbing and su jilan second institute of oceanography, state oceanic administration, hangzhou, china

A two-dimensional numerical model is constructed to study the interaction between the coastal upwelling and the coastal front off Zhejiang coast in summer. In the f-plane model, the shelf topography, continuous stratification, and Richardson number-dependent eddy coefficients are considered. The results show that the coastal up-welling off Zhejiang in summer can be divided into two regions, the nearshore one (Region A) and the offshore one (Region B). In Region A, the alongshore wind stress has more important effect on the coastal upwelling while in Region B, the upwelling is mainly induced by the Taiwan Warm Current. The results also suggest that the formation of coastal front off Zhejiang in summer is closely related to the strength of the coastal upwelling in Region A.

关键词： A numerical study for the coastal upwelling and the coastal front off Zhejiang coast

Currents in the Luzon Strait during the spring of 2002: observation and computation by modified inverse model

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Acta Oceanologica Sinica 2005年第1期24卷 1-13页

作者： YUANYaochu LOURuyun LIUYonggang sujilan wangkangshan CHENHong secondinstituteofoceanography StateOceanicAdministrationHangzhou310012China／／KeyLaboratoryofOceanDynamicProcessesandSatelliteOceanographyofStateOceanicAdministrationHangzhou310012China secondinstituteofoceanography StateOceanicAdministrationHangzhou310012China／／CollegeofMarineScienceUniversityofSouthFloridaU.S.A. secondinstituteofoceanography StateOceanicAdministrationHangzhou310012China

On the basis of the current measurements at 200,500 and 800 m from moored current meters with the time series data from March 17 to April 15 at the mooring station (20°49′57″N, 120°48′ 12″E) and the hydrographic data obtained in the Luzon Strait during the spring of 2002 cruise, the circulation in the investigated area is computed by using the modified inverse method. The major observed results are as follows: (1) the average velocity and the flow direction in the observing days are (47.4 cm/s, 346°) at the 200 m level. The average velocity in the observing days is (20.3 cm/s, 350? at the 500 m level. These mean that the Kuroshio intrudes into the South Chin Sea to flow northwestward through the Luzon Strait at 200 and 500 m levels. (2) The average velocity in the observing days is (1.2 cm/s, 35°) at the 800 m level, i. e., its direction is northeastward. This means that the flow condition at the 800 m level very differs from mat at the 200 and 500 m levels. (3) There is the high density and cold water (HDCW) in the middle of western part of in the investigated region, and its center is located near the hydrological station 3 at Section A. (4) There is the lower density and warm water (LDWW) in the southeastern part of investigated region. (5) The currents in April 2002 are stronger than those in March *** major computed results are as follows: (1) The northwestward and southeastward VTs through Section B are 32.48×106 m3/s (inclusive of VT of anticyclonic eddy) and 3.34×106m3/s, respectively. The net northwestward VT through Section B in the investigated area is about 29.14×106 m3/s. (2) The eastern and western VTs through Section A are about 16.71×106 and 8.57×106 m3/s, respectively. Thus, the net eastward VT through Section A is about 8.14×106 m3/s. (3) The net northward VT through Section M is about 24.68×106 m3/s. (4) After about 24.68×106 m3/s flows through Section M, most of it, about 16.54×106 m3/s, flows northward through the eastern part of Section C

关键词： currents in the Luzon Strait during the spring of 2002 currents measurements modified inverse method

Study on fluctuations of plume front and turbidity maximum in the hangzhou Bay by remote sensing data

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Acta Oceanologica Sinica 1993年第1期12卷 51-62页

作者： Li Yan Li Jing su jilan and Ren Fuhu second institute of oceanography, state oceanic administration, hangzhou 310012. china institute of Remote Sensing, Peking University, Beijing 100871, china second institute of oceanography State Oceanic Administration Hangzhou 310012 China China

On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the hangzhou Bay, reflected by the distributions of temperature and suspended sediment concentration respectively, are studied in view of long-term behaviors or seasonal and tidal cycles. The data suggest that the effect of front plays an important role in the development of the turbidity maximum close to the Changjiang Estuary > while the effect of tide dominates over the development of another very turbid water situated in the shoal areas in the southern hangzhou Bay.

关键词： esturary front suspended sediment remote sensing geographical information system hangzhou Bay

Practical implementation of Hilbert-Huang Transform algorithm

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Acta Oceanologica Sinica 2003年第1期22卷 1-14页

作者：黄大吉赵进平苏纪兰 Laboratory of the Ocean Dynamic Processes and Satellite oceanography Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China

Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better than MPM for the signal that has strong asymmetric waveform. However, it has to perform extrema envelope extending in every shifting process.

关键词： Hilbert-Huang Transform (HHT) signal processing Empirical Mode Decomposition (EMD)