It is of practical significance to investigate shallow water tides sinec there is a vast expanse of shallow sea surrunding our eastern border in the cast. In this paper for the study of tidal waves in ahalIow water we present a three-dimentional nonlinear model. On the basis of tidal constituent concept, the model dosigned could be used not only for the detoction of astronomical tides but also for aifferent orders of shallow water comstituents. For the jta order of constinents (as defined in the present artiele), the boundary value problews of elliptie differential equations for the tidal elevation are derived; in addition, the analytical expressins of the vertical distribution for tidal corrents are deduced.

首先評介了近海環流理論發展歷程及當前研究背景。簡介了作者及其合作者建立的近海環流理論的新框架，特別介紹了其最新進展；建立了一個描述近海環流的廣義方程組。其速度場是以一個廣義物質輸運速度來體現的，而“廣義物質輸運速度”乃“物質輸運速度”與近海系統中和潮流同樣占優的“準定常流”之和。發展的這一廣義模型具有下列兩個王要特征：①它不僅適用于僅潮流占優的近海系統，也同樣適用于還存在與潮流同階占優的準定常流的情形，如適用于存在黑潮強流的東中國海系統或某些潮河口洪水期的大徑流情況。②它是一個非線性耦合了近海天文湖和環流的κ-ε湍封閉系統。這里一個附加貢獻是齊次湍動能封閉模型的提出及其在近海系統中對某些運動形式、特別是對正壓潮流作數值模擬的適用性。最后，簡介了上述近海環流理論的新框架在環流本身、長期輸運及生態動力學諸萬面的某些實際應用。

基于一個非均勻的不可壓縮湍流方程組，首先給出了Ekman漂流的密度機制；其次，導出了一個“風旋度——熱鹽梯度方程式”，并對基進行了一般分析。利用該方程式建立了一個大洋風生——熱鹽歪流的丙層模型，并與觀測和某些經典的大洋環流模型作了分析比較。

In a joint project (1997-2000), the University of Hamburg (Germany) and the Ocean University of Qingdao (China) have investigated the circulation, water mass structure, nutrient fluxes and phytoplankton dynamics in the Bohai Sea. A hierarchy of coupled circulation, transport and production models for the seasonal scale has been developed and tested against field data from two ship cruises in autumn and spring. The models are available now for scenario calculations under the impact of environmental change.

The transports of solutes and other tracers are fundamental to estuarine processes. The apparent transport mechanisms are convection by tidal current and current-induced shear effect dispersion for processes which take place in a time period of the order of a tidal eyele. However, as emphasis is shifted toward the effects of intertidal processes, the net transport is mainly determined by tide-induced residual circulation and by residual circulation due to other processes. The commonly used intertidal conservation equation takes the form of a convection-dispersion equation in which the convective velocity is the Eulerian residual current, and the dispersion terms are often referred to as the phase effect dispersion or, sometimes, as the "tidal dispersion." The presence of these dispersion terms is merely the result of a Fickian type hypothesis. Since the actual processes are not Fickian, thus a Fickian Hypothesis obscures the physical significance of this equation. Recent research results on residual circulation have suggested that long-term transport phenomena are closely related to the Lagrngian residual current or the Lagrangian residual transport. In this paper a new formulation of an intertidal conservation equation is presented and examined in detail. In a weakly nonlinear tidal estuary the resultant intertidal transport equation also takes the form of a convection-dispersion equation without the ad hoc introduction of phase effect dispersion in a form of dispersion tensor. The convective velocity in the resultant equation is the first-order Lagrangian residual current (the sum of the Eulerian residual current and the Stokes drift). The remaining dispersion terms are important only in higher-order solutions; they are due to shear effect dispersion and turbulent mixing. There exists a dispersion boundary layer adjacent to shoreline bound-anesAn order of magnitude estimate of the properties in the dispersion boundary layer is given. The present treatment of intertidal transport processes is illustrated by an analytical solution for an amphidromicsystem and by a numerical application in South San Francisco Bay, California. The present formulation reveals that the mechanism for long-term transport of solutes is mainly convection due tothe Lagrangian residual current in the interior of a tidal estuary. This result also points out the weakness in the tidal dispersion formulation, and explains the large variability of the observed values for tidal dispersion coefficients. Further research on properties of the dispersion boundary layer is needed.

Using a three-dimensional weakly nonlinear baroclinic shallow water model, the Lagrangian residual velocity associated with a multi-frequency tidal system has been analyzed. The first-order Lagrangian residual velocity, the mass-transport velocity, has been shown to be the sum of the mess-transport velocities derived from the respective constituencs of astronomical tides, and boch the wind-driven (barotropic) and the density-driven (baroclinic) componencs. The second-order perturbacion Lagrangian residual velocity, i.e., the Lagrangian drift velocity, has been shown to involve a series of nonlinear interactions between the products of the respective conscitutuents of tides, and reflects the periodicities of all the constituents of astronomical tides contained in the multi-frequency tidai system through the initial phases. AS an example, the Lagranglan drift velocity induced by an M2-S2 tidal system is analyzed in detail for a more thorough understanding of the mechanism of nonlinear interactions of the second-order dynamics. A coupled set of nonlinear field equations for the mass-transport velocicy and the zeroth-order apparent comcentration has been derived and used to describe and understand the shallow water residual circulation along with the intertidal transport processes coupled by the wind stress over the sea surface, the heat flux across the water surface, the horizontal gradient of water density, and the tidal body force resuleing from the nonlinear interaction among the multi-frequency astromomical tidal variables. An application of the model to the summer. The tide-induced component of the residual circulation in the Bohai Sea is more appropriately associated with and M2-K1 tidal system than an M2-tidal system alone.