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1.
2.
Feng Shizuo 《中国海洋湖沼学报》1986,4(2):139-158
In recent years, studies of the environmental hydrodynamics in coastal seas and tidal estuaries have placed focus on the processes
which determine the “fate” of longer-term transport. The lagrangian residual current has been recognized as an important factor
which affects the longer term transport processes since it is more relevant to use a Lagrangian mean velocity rather than
an Eulerian mean velocity to determine the origin of Water masses. In the present paper, an attempt is made to formulate a
three-dimensional dynamics on the tideinduced Lagrangian residual current and mass-transport based upon a three-dimensional
weakly-nonlinear model of tides. The Lagrangian residual velocity is shown to be the sum of the mass-transport velocity, which
is the sum of the Eulerian residual velocity and the Stokes’ drift velocity, and the Lagrangian residual drift velocity which
is dependent on the tidal current phase. This reveals that it is the mass-transport velocity which is the tidal cycle Eulerian
mean of the Lagrangian residual velocity and that the mass-transport velocity is correct to the second order of approximation
rather than to the first order. And then, a new longer-term transport equation which correctly describes the Lagrangian nature
of transport processes without introducing the Fickian hypothesis for tidal dispersion is derived. In fact, the convection
can be correctly represented by the Eulerian mean of the Lagrangian residual velocity, as the convective velocity in the longer-term
transport equation is nothing but the mass-transport velocity.
Submitted for IAMAP/IAPSO Joint Assembly, August 5–16, 1985, Honolulu, Hawaii U.S.A. 相似文献
3.
INTRODUCTIONAsoneofthemethodsenablingnumericalsolutionofdifferentialequations,thefinite differ encemethodiswidelyacceptedinthestudyofphysicaloceanography.Afinite differenceschememusthavepropertiesofconvergence ,consistencyandstabilitytoyieldusefulapproximatesolutionoftherelevantdifferentialequations.However,thepropertiesneednotbeverifiedonebyonebecausethewell knownLaxLawassuresthattheconvergenceisequivalenttothestabilityforafinitediffer enceschemewithconsistence .Twomainmethodsforstudyin… 相似文献
4.
吴德星 《中国海洋湖沼学报》1997,15(4):314-321
ImODUcnONThedeepequatorialoceanhasobvioussignilicantflowapparentlycarryinghacelsa1ongandacrosstheequator(WissCtal.,l985).RmtfloatmsurementSshoWedthattheflowishigh1yvariable(Richardsonetal.,l993).ThomPsonandKawase(l993)pro-posedthatthelargeinstantaneousandfloatvelocitiesasWellasthevariabilitysuggestthatthetracersignaIsreflCCtreCtificationoftimedependentmotionsandniinginsteadofrneanEulerianflow.TheresultSoftheirstudyonthegenerationofmeancurrentSbyperi-odicfordngintheequatorialoceaninasir… 相似文献
5.
On small-meso scale, the sea ice dynamic characteristics are quite different from that on large scale. To model the sea ice dynamics on small-meso scale, a new elastic-viscous-plastic （EVP） constitutive model and a hybrid Lagrangian- Eulerian （HLE） numerical method are developed based on continuum theory. While a modified discrete element model （DEM） is introduced to model the ice cover at discrete state. With the EVP constitutive model, the numerical simulation for ice ridging in an idealized rectangular basin is carried out and the results are comparable with the analytical solution of jam theory. Adopting the HLE numerical model, the sea ice dynamic process is simulated in a vortex wind field. The furthering application of DEM is discussed in details for modeling the discrete distribution of sea ice. With this study, the mechanical and numerical models for sea ice dynamics can be improved with high precision and computational efficiency. 相似文献
6.
Inter-tidal(subtidal) transport processes in coastal sea depend on the residual motion, turbulent dispersion and relevant sources/sinks. In Feng et al.(2008), an updated Lagrangian inter-tidal transport equation, as well as new concept of Lagrangian in- ter-tidal concentration(LIC), has been proposed for a general nonlinear shallow water system. In the present study, the LIC is nu- merically applied for the first time to passive tracers in idealized settings and salinity in the Bohai Sea, China. Circulation and tracer motion in the three idealized model seas with different topography or coastline, termed as ‘flat-bottom', ‘stairs' and ‘cape' case, re- spectively, are simulated. The dependence of the LIC on initial tidal phase suggests that the nonlinearities in the stairs and cape cases are stronger than that in the flat-bottom case. Therefore, the ‘flat-bottom' case still meets the convectively weakly nonlinear condi- tion. For the Bohai Sea, the simulation results show that most parts of it still meet the weakly nonlinear condition. However, the de- pendence of the LIS(Lagrangian inter-tidal salinity) on initial tidal phase is significant around the southern headland of the Liaodong Peninsula and near the mouth of the Yellow River. The nonlinearity in the former region is mainly related to the complicated coast- lines, and that in the latter region is due to the presence of the estuarine salinity front. 相似文献
7.
The Cold Eddy in the East China Sea (CEECS) is located about 150 km southwest of Cheju Island. This region experiences a complex
current system under the influences of the Yellow Sea Warm Current (YSWC), the Yellow Sea Coastal Current (YSCC), and the
northward Kuroshio residual. To identify the strength of the CEECS, a simple subsurface intensity index is developed. Because
the CEECS can be traced by temperature minimum, the intensity index is determined by the difference in sea temperature averaged
across cores within and surrounding the region. Based on SODA, the CEECS subsurface intensity index time series can be calculated,
with which the inter-annual variation of the CEECS is analyzed. 相似文献
8.
There are two different modeling approaches which have been proposed and utilized to derive residual currents: the first approach
is equivalent to deducing residual currents from current-meter records using filtering techniques or time averages of time-series
records to remove tidal variations; in the second approach, filters or time averages over several tidal cycles are applied
to the hydrodynamic equations to generate the governing equations for residual circulation. Based on the latter, both the
baroclinic dynamic models of residual circulation are proposed, of which one is a two-dimensional transport model and the
other is a three-dimensional model with variable eddy viscosity. The two-dimensional transport model is a direct generalization
from the barotropic model of residual circulation presented by Nihoul and Randy (1975) and Heaps (1978) to the baroclinic
model. In the three-dimensional model with variable eddy viscosity, using a Sturm-Liouville system adopted in the reference
[5], the nondimensional problem for residual circulation reduces to the nondimensional problem of the elevation and the expression
of residual currents.
It should be pointed out that both the baroclinic models developed in the present paper are confined to describe the Eulerian
residual circulation only. 相似文献
9.
Lu Youyu 《中国海洋湖沼学报》1991,9(2):184-192
A multiple time scale perturbation method is used to discuss the Lagrangian residual current and residual transport on the
basis of a weakly nonlinear dynamic model of shallow seas. The governing equations for the long-term variation of zero order
“apparent concentration” (which is a linear combination of salinity, temperature of seawater and the concentration of any
tracer which is conservative and passive) and its mean value over tidal cycles are obtained for the system with single tidal
constituent, and for the one with multi-constituents, winds and thermohaline. The equations for the two cases are in the same
form and show this long-term variation resulted from the cumulative effect of residual convection and turbulent diffusion.
The multiple time scale variation of current is caused by tides, winds, and the thermohaline and the nonlinear effects of
the system. The derived set of governing field equations of the Lagrangian current for this multiple time scale system is
also in the same form as that for a single time scale system. 相似文献
10.
In this paper, we use the optimum interpolation sea surface temperature (OISST) provided by the National Center for Environmental Prediction (NCEP) to replace the temperature in the top three layers in the ISHII data, and make use of the modified ISHII temperature data to calculate the thermosteric sea level (called modified steric sea level (SSL) hereafter). We subtract the modified SSL and the steric sea level (called ordinary SSL hereafter) derived from the ISHII temperature and salinity from the steric sea level (SSL) provided by the Gravity Recovery and Climate Experiment (GRACE), respectively, and find that the rms error of the difference of the former is obviously smaller than that of the latter. Therefore we reach the conclusion that under the assumption that the GRACE SSL is accurate, the modified SSL can reflect the true steric sea level more accurately. Making use of the modified SSL, we can find that the modified SSL in sea areas of different spatial scales shows an obvious rising trend in the upper 0-700 m layer for the period 1982-2006. The global mean SSL rises with a rate of 0.6 mm year-1 .The modified SSLs in sea areas of different spatial scales all show obvious oscillations with period of one year. There are oscillations with periods of 4-8 years in global oceans and with periods of 2-7 years in the Pacific. The Empirical Orthogonal Function method is applied to the sea areas of different spatial scales and we find that the first modes all have obvious 1-year period oscillations, the first mode of the global ocean has 4-8 year period oscillations, and that of the Pacific has 2-6 year period oscillations. The spatial distribution of the linear rising trend of the global modified SSL in the upper 0-700 m layer is inhomogeneous with intense regional characteristics. The modified SSL linear trend indicates a zonal dipole in the tropical Pacific, rising in the west and descending in the east. In the North Atlantic, the modified SSL indicates a meridional dipole, rising in the latitude band of 20°N-40°N and 45°N-65.5°N and descending obviously in the latitude band of 40°N-45°N. 相似文献
11.
山东半岛海域成矿区带划分以往研究程度较低。该文利用海域重磁资料,在研究区梳理了渤海和黄海的重磁异常特征,渤海和北黄海呈负布格重力异常,南黄海北部与之相反;渤海为正磁异常,黄海与之相反。以重磁异常为基础,基于陆域构造单元划分,对海域构造单元划分至Ⅲ级10个构造单元,海域构造单元多为陆域向海域的延伸,仅渤中坳陷和北黄海盆地为独立的海域构造单元。参照陆域成矿区带划分,以构造单元边界为界线,海域成矿区带划分至Ⅳ级6个成矿区,各成矿区特征不同,坳陷构造单元内成矿区富集油气矿产,隆起构造单元内成矿区表现为埕宁隆起富集煤矿,胶北隆起富集金、菱镁矿、煤、灰岩矿,千里隆起富集岩金、蛇纹岩、石棉、花岗石矿。 相似文献
12.
Lu Jinghua Zhao Bangjie 《成都信息工程学院学报》1989,(2)
在正形投影坐标系下,半拉格朗日法与半隐式法相结合积分浅水波方程导出的模式,用一小时的时间步长,是无条件稳定。我们作了一个60小时的实例时间积分,计算稳定。半隐式积分格式导致求解一个赫姆霍茨方程,为比较其高低精度的优劣,我们提出在空间上用二阶精度和四阶精度解赫姆霍茨方程的超松驰法,同时,作了有无地形的试验。应该注意列,半拉格朗日法含有大量的插值,因而,在每一步时间步长里此积分格式比通常的欧拉法含有更多的计算,但是每一时间步长的计算量的增加却从使用很大的时间步长得到了更多的补偿。 相似文献
13.
用交叉点数据计算中国近海海平面变化 总被引：2，自引：0，他引：2
讨论了由测高卫星升、降弧段海面高在交叉点上的约束监测海平面变化的方法；用TOPEX／POSIDON测高数据计算了中国黄海、东海、南海海域的海平面变化，其中黄海、东海海域受两个月周期分量的振荡信号影响，而南海海域以年周期变化为主要表现特征；分析了3个海区海平面变化的相关性，扣除两个月的周期分量振荡信号后，其海平面变化的相关性达到90％以上；分析了海水面积随纬度带的变化对不同纬度分布的海区海平面变化量的影响。 相似文献
14.
Based on a coupled hydrodynamic-ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model
for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical
direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the “dry-wet” method
were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation
stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included
in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport
and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from
outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion
in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two
types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution
forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the
Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of
the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with
pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water
flow, and the backward flow of pollutants released upstream is more obvious. 相似文献
15.
The Chinese east coastal areas and marginal seas are foggy regions.The development of effective forecasting methodsrests upon a comprehensive knowledge of the fog phenomena.This study provides new observations associated with the sea fogsover the northwestern Yellow Sea by means of L-band radar soundings with a high vertical resolution of 30 m.The monthly tem-perature lapse rate,the Richardson Numbers,and the humidity show obvious seasonal variations in the lower level of the planetaryboundary layer (PBL) that are related to the onset,peak and end of the Yellow Sea fog season.The typical pattern of stratification forthe sea fog season in the northwestern Yellow Sea is that a stable layer of about 400 m thick caps a 150 m conditionally unstable layer.Besides,the differences between fogs and stratus clouds in terms of humidity,turbulence and temperature are analyzed,which is ofsignificance for sea fog forecast and detection by satellites.The thickness of the sea fogs varies in different stages of the fog season,and is associated with the temperature inversion.The numerical simulation proves that the seasonal variations obtained by the radarwell represent the situations over the Yellow Sea. 相似文献
16.
Snow on sea ice is a sensitive indicator of climate change because it plays an important role regulating surface and near surface air temperatures. Given its high albedo and low thermal conductivity, snow cover is considered a key reason for amplified warming in polar regions. This study focuses on retrieving snow depth on sea ice from brightness temperatures recorded by the Microwave Radiation Imager(MWRI) on board the FengYun(FY)-3 B satellite. After cross calibration with the Advanced Microwave Scanning Radiometer-EOS(AMSR-E) Level 2 A data from January 1 to May 31, 2011, MWRI brightness temperatures were used to calculate sea ice concentrations based on the Arctic Radiation and Turbulence Interaction Study Sea Ice(ASI) algorithm. Snow depths were derived according to the proportional relationship between snow depth and surface scattering at 18.7 and 36.5 GHz. To eliminate the influence of uncertainties in snow grain sizes and sporadic weather effects, seven-day averaged snow depths were calculated. These results were compared with snow depths from two external data sets, the IceBridge ICDIS4 and AMSR-E Level 3 Sea Ice products. The bias and standard deviation of the differences between the MWRI snow depth and IceBridge data were respectively 1.6 and 3.2 cm for a total of 52 comparisons. Differences between MWRI snow depths and AMSR-E Level 3 products showed biases ranging between-1.01 and-0.58 cm, standard deviations from 3.63 to 4.23 cm, and correlation coefficients from 0.61 to 0.79 for the different months. 相似文献
17.
Wang Zhaohui Lei Mingdan Ji Shuanghui Xie Changliang Chen Jiazhuo Li Weiguo Jiang Tao 《中国海洋湖沼学报》2022,40(6):2322-2342
Journal of Oceanology and Limnology - Surface sediment samples were collected in three different functional sea areas in Qingdao coast, East China, including the inner Jiaozhou Bay, the Laoshan... 相似文献
18.
YU Yunli WANG Deguan WANG Zhigang LAI Xijun 《中国海洋大学学报(英文版)》2006,5(1):7-11
A two-dimensional numerical model is proposed to simulate the thermal discharge from a power plant in Jiangsu Province. The equations in the model consist of two-dimensional non-steady shallow water equations and thermal waste transport equations. Finite volume method （FVM） is used to discretize the shallow water equations, and flux difference splitting （FDS） scheme is applied. The calculated area with the same temperature increment shows the effect of thermal discharge on sea water. A comparison between simulated results and the experimental data shows good agreement. It indicates that this method can give high precision in the heat transfer simulation in coastal areas. 相似文献
19.
彼此相邻的海域之间由于用海类型的不同,经常存在相互的干扰和影响。本文以国家海洋功能区划中规定的海洋功能区分类及海洋环境保护要求为基础,设计了用海变化的自动检测方法。根据不同海洋功能分区的海水水质质量的标准建立缓冲区检测算法和历史用海检测算法,缓冲区检测算法用来检测同一时期不同位置的用海是否存在冲突;历史用海检测算法用来检测同一位置不同时期的用海是否存在冲突。在两种检测算法的基础上,利用地理信息系统开发组件实现了对新加入宗海及原宗海用海变更的自动检测功能,并以上海海洋功能区划数据为测试数据,验证了作为海籍空间信息管理系统的核心功能之一,可以实现用海变化的自动检测,满足对宗海空间变化和时间变化的信息化管理。 相似文献
20.
方之芳 《成都信息工程学院学报》1992,(2)
本文应用1953～1984年的北极海冰资料,分析各区海冰的季节变化、年际变化、自相关特性及互相关特性。认为Ⅰ区海冰占有最大权重,又具有较大的方差,在全区海冰中起着重耍作用。冬季,各区海冰相互关联,其余季节,基本上相互独立。各区海冰均提供了气候“贮存”机制,一个季节的冰能影响下一个季节冰的特性;冬季的贮存能力大于夏季,春秋次之;Ⅱ区和Ⅳ区冰的持续性优于Ⅰ区 。 相似文献