A three-dimensional time-dependent model on coastal upwelling

Hu (1979) proposed a two-dimensional, unsteady, homogeneous coastal upwelling model with finite constant depth. Lu and Zhao (1985) extended Hu’s model by specifying a linear bottom slope. A three-dimensional, unsteady, homogeneous, coastal upwelling model on f-plane with arbitrarily linear bottom slope is suggested in this paper as an extension of Lu and Zhao’s model. The solution for such a problem has been obtained, and the properties of upwelling and horizontal current are examined. Contribution No. 1491 from Institute of Oceanology, Academia Sinica     

Numerical study on inter-tidal transports in coastal seas

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.     

Wind energy input in coastal seas east of China

This study investigates the wind energy input, an important source of mechanical energy, in the coastal seas east of China. Using the wind field from the high-resolution sea surface meteorology dataset in the Bohai Sea, Yellow Sea, and East China Sea, we studied the wind energy input through surface ageostrophic currents and surface waves. Using a simple analytical formula for the Ekman Spiral with timedependent wind, the wind energy input through ageostrophic currents was estimated at ～22 GW averaged from 1960 to 2007, and through use of an empirical formula, the wind energy input through surface waves was estimated at ～169 GW. We also examined the seasonal variation and long-term tendency of mechanical energy from wind stress, and found that the wind energy input to the East China Sea decreased before the 1980s, and then subsequently increased, which is contrary to what has been found for the Bohai Sea and Yellow Sea. More complicated physical processes and varying diffusivity need to be taken into account in future studies.     

Chemical hydrography of coastal upwelling in the East China Sea

Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles and horizontal distributions of chemical and hydrographic variables. Results show that the coastal upwelling was year-round, but the areas and intensities of the upwelling were quite different in season. The coastal upwelling occurred in all of the coastal areas of the region in spring and summer, but in autumn only in the area off Zhejiang Province, and in winter in the area off Fujian Prov- ince. It was the strongest in summer and the weakest in winter. Geographically, it was the strongest in the area off Zhejiang Province and the weakest in the southmost or northmost parts of the East China Sea. The estimated nutrient fluxes upward into euphotic zone through coastal upwelling were quite large, es- pecially for phosphate, which contributed significantly to primary production and improved the nutrient structure of the coastal ecosystem in the East China Sea.     

Theoretical study on coastal upwelling induced by alongshore current

The perturbation method is used to derive this mathematical model for coastal upwelling induced by alongshore current at the shelf break on a slowly sloping continental shelf. The geostrophic flow velocity with bottom friction as the velocity at the shell" break is presumably the best choice for the homogeneous model.The present analysis will be beneficial to understanding and further study of the upwelling induced by an alongshore current.     

UPWELLING AND SEDIMENTATION DYNAMICS Ⅲ：COINCIDENCE OF UPWELLING AREAS WITH MUD PATCHES IN NORTH HEMISPHERE SHELF SEAS

The determinant role of upwelling in fine sediment patches is examined from the view-points of physical process and biological process respectively. It is pointed out that physical and biologicalprocesses are usually coexistent and interact with each other during the sedimentation of suspended mat-ters. This study used available figures showing the circulation pattern and surface sediment distribution inthe whole China Seas, the Gulf of Maine, the Irish Sea and the North Sea, and additional data to verifythat wherever upwelling exists on the continental shelf, mud must occur; and that wherever dowrtwellingoccurs, coarse sediment substitutes for mud.     

A continuously stratified nonlinear model for internal solitary waves in the northern South China Sea

A continuously stratified nonlinear model is set up to study the impact of topographical character on the generation of internal solitary waves over a sill by tidal flow. One of the reasons why almost all of the generated internal solitary waves propagate westward in the northern South China Sea is explained. The model simulations describe the generation and propagation of internal waves well. When the strength of imposed barotropic tides and the water stratification stay unchanged, the steepness of the sill slope can control both (a) whether or not the waves induced over a sill by tidal flow are linear internal waves or nonlinear internal solitary waves, and (b) the amplitude of the internal solitary waves generated. If the steepness of the sill is asymmetric, the nonlinear internal solitary waves may be induced on the steeper side of the sill. These conclusions are supported by a numerical experiment with a monthly-mean stratification and an actual seafloor topography from the Luzon Strait.     

China coastal seas under severe sea state: remote sensing and dynamics studies

<正>Severe sea state,which features huge ocean waves under strong surface wind and often comes along with heavy rainfall,storm surge,and coastal f looding,is associated to a range of disastrous ocean dynamic environments,including storm surge,disastrous wave,internal wave,etc.,and bring serious economic damage and safety threat to coastal area.In China,previous studies have shown that the storm surge had the highest     

The upper mixed layer during coastal upwelling events on the northern portugal shelf

The upper mixed layer (UML) depth obtained from temperature is very close to that from density:the maximum is about 15m. This indicates that temperature is a good indicator of mixed layer during measurements. When the surface heat flux is balanced by a cross-shore heat flux, the surface mixed layer depth obtained from the WM model (Weatherly and Martin, 1978),hPRT, is roughly the same as observed. The mixed layer depth calculated from the PWP model (Price, Weller and Pinkel, 1986) is close to the depth obtained from thermistor chain temperature data. The results show that both the WM model and PWP model can provide a good estimate of stratification in the study area during the cruise. The value of log( h/u3) is about 9.5 in the study area, which shows that the study area is strongly stratified in summer. Observations on the northern Portugal shelf reveal high variability in stability, giving rise to semi-diurnal, semi-monthly and diurnal oscillations, and long term variations. The fortnightly oscillatio     

Projections of changes in marine environment in coastal China seas over the 21st century based on CMIP5 models

Journal of Oceanology and Limnology - The increases of atmospheric carbon dioxide and other greenhouse gases have caused fundamental changes to the physical and biogeochemical properties of the...     

The characteristic pattern of multiple colored layers in coastal stratified lakes in the process of separation from the White Sea

An unusual feature of the saline stratified lakes that were formed due to ongoing postglacial uplift on the White Sea coast is the presence of several differently colored thin layers in the zone with sharp gradients. Colored layers in five lakes at various stages of separation from the sea were investigated using optical microscopy, spectrophotometry, spectrofluorimetry, and photobiology. The upper greenish colored layer located in the aerobic strata of all lakes near the compensation depth of 1% light penetration contains green algae. In the chemocline, another layer, brightly green, red or pink, is dominated by mixotrophic flagellates. Despite the very low light intensities and the presence of H 2 S, active photosynthesis by these algae appears to be occurring, as indicated by high values of the maximum quantum yield of primary photochemistry, electron transport activity, photosynthetic activity of photosystem II, the fraction of active centers, and low values of heat dissipation. In the reduced zone of the chemocline, a dense green or brown suspension of anoxygenic phototrophs(green sulfur bacteria) is located.     

海岸带环境系统与海岸带信息系统

本文提出海岸带环境系统的概念模型,分析了海岸带环境系统动态变化的驱动因素,论述了自然控制和等级调控理论、全球变化和区域调控理论是海岸带环境系统调控的理论基础。阐述海岸带环境系统调控的信息机理。海岸带综合管理是海岸带环境系统调控的一个主要途径。在地理信息系统和遥感技术支持下进行海岸带信息集成与综合,并以此为基础建立复杂的海岸带环境系统动态时空模型,为实施海岸带综合管理和调控提供科学依据。     

The baroclinic residual circulation in shallow seas

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.     

Heat flow in northwest Pacific marginal seas

1 INTRODUCTION Marginal seas in the Northwest Pacific includethe Bering Sea, the Okhotsk Sea, the Japan Sea, theEast China Sea, the South China Sea and the Philip-pine Sea, surrounded by adjacent coastal regions,the islands on the continental crust side and theocean trench at oceanic crust side. More than 4000heat flow data have been obtained since the firstmeasurement in the area in 1957 around the Japa-nese Islands (Uyeda and Horai, 1964) and the firstmarine survey in the Be…     

INTERNAL TIDES, SOLITARY WAVES AND BORES IN SHALLOW SEAS

Remote sensing and in situ observations of internal tides, solitary waves and bores in shallow water are briefly reviewed in this paper. The emphasis is laid on interpreting SAR images based on oceanographic measurements, and analyzing characteristics of internal waves in the China Seas. Direc-tions for future research are discussed.     

Spatio-temporal distribution of dissolved sulfide in China marginal seas

With sulfide increasingly recognized as an important parameter to assess the oxidation-reduction level in aqueous environment, research on its geochemical behavior is becoming important. Water samples collected in Bohai Sea(1–19 August, 2010), Yellow Sea(20–30 November, 2010) and East China Sea(3–17 June, 2010 and 1–10 November, 2010) were used to determine the occurrence and distribution of dissolved sulfide by methylene blue spectrophotometric method. Results show that:(1) horizontally, concentration of dissolved sulfide significantly varied from the coastal region to the open sea and profoundly influenced by physical processes. High values occurred in the river-sea boundary zone "marginal filter" due to rich riverine input, frequent upwelling and active exchange in shelf edge. Terrestrial input from adjacent rivers and the current cycling contributed to the high sulfide appeared in western Bohai Sea, eastern Shandong Peninsula, and northeast of Changjiang(Yangtze) River estuary. Especially, relative higher sulfide values occurred in Yellow Sea, which is consistent with the variation of salinity largely due to the hydrodynamic feature;(2) vertically, measurement of dissolved sulfide in bottom water was higher and more variable than that in surface water caused by the wind-induced resuspension and dissimilatory sulfate reduction. Moreover, nutrient-type profile clearly identified that oxidation plays a major role in the biogeochemistry cycle of sulfide in water;(3) seasonally, investigation for East China Sea in June and November reflected seasonal variation of Changjiang River Diluted Water, Kuroshio Current, and Taiwan Warm Current. Concentration in June was much higher than that sampled in November at most stations. Mean concentration of dissolved sulfide varied seasonally from 2.26 μg/L(June) to 1.16 μg/L(November) in surface and 3.00 μg/L(June) to 1.56 μg/L(November) in bottom. Progress in the field is slow and more effort is needed to ensure the accuracy and reliability of determination and estimate the natural or anthropogenic contribution of dissolved sulfide in ecosystems.     

Estimates of potential new production in the Java-Sumatra upwelling system

The Java-Sumatra upwelling is one of the most important upwelling systems in the Indian Ocean, with maximum upwelling intensity in July through August. To estimate the nitrate supplied by upwelling, we developed a three-dimensional hydrodynamic model to calculate the mean vertical speed and determine the depth of upwelling. We used in-situ vertical nitrate profiles to assess nitrate concentration in the upwelled waters, and calculated the nitrate supply as the product of nitrate concentration and vertical transport obtained from the numerical model. The calculated result represents potential new production generated in the upwelling region. We found that on the event time scale (monthly) of Java-Sumatra upwelling, water brought to the surface originated from locations 100-m deep, giving a nitrate supply of 93.77×10 3mol/s and potential new production of 1.02×10 14gC/a.     

山东省渤海沿岸湿地价值估算与保护对策

山东省渤海沿岸湿地价值估算的目的是提醒公众尤其是政府决策部门关注湿地的综合功能,而不是也不应该单纯向湿地索取,更不能破坏性地开发,需要科学保护和合理利用,以使湿地可持续利用。通过分析湿地动态影响因素,提出了湿地保护管理的对策措施。