JONSWAP's parameters: Sorting out the inconsistencies     

A.W. Lewis  R.N. Allos 《Ocean Engineering》1990,17(4)

The original prognostic equations for the JONSWAP-spectrum contained inconsistencies. A subsequent paper (Hasselmann et al., 1976, J. phys. Oceanogr.6, 200–208) attempted to regularise the situation. This paper shows that there were still inconsistencies in the prognostic equations giving overestimations of the first moment of the spectrum and consequently the significant wave height. The prognostic equations are reworked systematically and results presented. It is shown that variable σ_a, σ_b and γ must be used to achieve consistent results  相似文献   

Maternal transfer of bioactive polychlorinated aromatic hydrocarbons in spawning chinook salmon (Oncorhynchus tschawytscha)     

Gerald T. Ankley  Donald E. Tillitt  John P. Giesy 《Marine environmental research》1989,28(1-4)

The biological potency (relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin. TCDD) of planar polychlorinated aromatic hydrocarbons (PCHs) in extracts of eggs and flesh from spawning female chinook salmon (Oncorhynchus tschawytscha) from Lake Michigan was determined by measuring the induction of 7-ethoxyresorufin O-deethylase activity in H-4-II-E rat hepatoma cells. TCDD-equivalents in flesh and egg samples ranged from 0 to 115·8 pg/g, and were approximately 5-fold greater in eggs than in flesh. These results suggest that the maternal transfer of PCHs may play a role in determining the reproductive success of Lake Michigan chinook salmon.  相似文献   

Study of fluoride in polluted and unpolluted estuarine environments     

M. D. Zingde  A. V. Mandalia 《Estuarine, Coastal and Shelf Science》1988,27(6)

Mindhola River estuary, which receives industrial waste containing high concentrations of fluoride, and Purna River estuary, which is free from fluoride contamination, have been investigated. While fluoride behaved conservatively in Purna River estuary, significant deviation from the theoretical dilution line (TDL) in the chlorinity range 0·5–8‰ was observed in Mindhola River estuary due to the externally added fluoride which largely remained in solution. The excess of fluroide over the theoretically calculated value was at a maximum around a chlorinity of 3‰. High natural fluoride content of the river waters resulted in F/Cl ratios exceeding 300 × 10⁻⁵ at low chlorinities. The ratio decreased rapidly with increasing chlorinity and the value near to that of seawater was observed at chlorinities above 14‰.  相似文献   

Nonlinear coupled response of offshore tension leg platforms to regular wave forces   总被引：1，自引：0，他引：1  

A.K. Jain 《Ocean Engineering》1997,24(7):577-592

Among the compliant platforms, the tension leg platform (TLP) is a vertically moored structure with excess buoyancy. The TLP is designed to behave in the same way as any other moored structure in horizontal plane, at the same time inheriting the stiffness of a fixed platform in the vertical plane. Dynamic response analysis of a TLP to deterministic first order wave forces is presented, considering coupling between the degrees-of-freedom surge, sway, heave, roll, pitch and yaw. The analysis considers nonlinearities produced due to changes in cable tension and due to nonlinear hydrodynamic drag forces. The wave forces on the elements of the pontoon structure are calculated using Airy's wave theory and Morison's equation ignoring diffraction effects. The nonlinear equation of motion is solved in the time domain by Newmark's beta integration scheme. The effects of different parameters that influence the response of the TLP are then investigated.  相似文献   

Transient soil response in a porous seabed with variable permeability     

Brian R. Seymour  Dong S. Jeng  John R.C. Hsu 《Ocean Engineering》1996,23(1):27-46

The soil permeability of many natural marine sediments decreases with depth because of consolidation under overburden pressure. This is accompanied by a decrease in porosity and void ratio that also affect the permeability. Conventional theories for wave-induced soil response have assumed a homogeneous porous seabed. This paper presents a new approach for the wave-induced response in a soil matrix, with variable permeability as a function of burial depth. The soil matrix considered is unsaturated and anisotropic, and is subject to a three-dimensional wave system. The pore pressure and effective stresses induced by such a system are obtained from a set of equations incorporating a variable permeability. Verification is available through reduction to the simple case of uniform permeability. The results indicate that the effect of variable soil permeability on pore pressure and vertical effective stress may be significant, especially in a gravelled seabed and for unsaturated sandy soils.  相似文献   

On the monitoring of the thermal state of the upper ocean     

Yu. D. Resnyansky  A. A. Zelen'ko 《Physical Oceanography》1995,6(2):117-124

This paper discusses some problems related to the development of systems of global monitoring of the sea surface temperature (SST). The characteristics of the operational SST data are considered and estimations of their accuracy are given. The applications of varoous models to the computation of SST in relation to the development of an oceanographic data assimilation system are reviewed briefly.Translated by Mikhail M. Trufanov.  相似文献   

Government response to marine pollution from ships     

John Bywater  Commander 《Marine Policy》1995,19(6)

The Marine Pollution Control Unit (MPCU) is the competent national authority for discharging the Secretary of State for Transport responsibility for pollution from ships under the Prevention of Oil Pollution Act 1971 and subsequent legislation covering other hazardous substances. It is an integral part of The Coastguard Agency, an executive agency of The Department of Transport. MPCU is responsible for maintaining the National Contingency Plan, for monitoring and assessing all pollution incidents within UK waters including dealing with pollution from ships and for advising on/co-ordinating shoreline counter pollution operations, and for fostering and maintaining international relationships for mutual support.  相似文献   

Sheet flow and suspension of sand in oscillatory boundary layers   总被引：1，自引：0，他引：1  

Jan S. Ribberink  Abdullah A. Al-Salem 《Coastal Engineering》1995,25(3-4)

after revisionTime-dependent measurements of flow velocities and sediment concentrations were conducted in a large oscillating water tunnel. The measurements were aimed at the flow and sediment dynamics in and above an oscillatory boundary layer in plane bed and sheet-flow conditions. Two asymmetric waves and one sinusoidal wave were imposed using quartz sand with D₅₀ = 0.21 mm. A new electro-resistance probe with a large resolving power was developed for the measurement of the large sediment concentrations in the sheet-flow layer. The measurements revealed a three layer transport system consisting of a pick-up/deposition layer, an upper sheet flow layer and a suspension layer.In the asymmetric wave cases the total net transport was directed “onshore” and was mainly concentrated in the thin sheet flow layer (< 0.5 cm) at the bed. A small net sediment flux was directed “offhore” in the upper suspension layer. The measured flow velocities, sediment concentrations and sedimenl fluxes showed a good qualitative agreement with the results of a (numerical) 1DV boundary-layer flow and transport model. Although the model did not describe all the observed processes in the sheet-flow and suspension layer, the computational results showed a reasonable agreement with measured net transport rates in a wide range of asymmetric wave conditions.  相似文献   

A quantitative analysis on the Egyptian Mediterranean waters     

M. A. Sai  F. M. Eid 《海洋学报(英文版)》1994,13(2):203-212

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THE CLIMATIC CHANGES AND THE COASTAL ENVIRONMENT     

F. Marabini Qing YunshanA. Veggiani Gang Shuxi 《海洋地质与第四纪地质》1992,(1)

Although the Yellow River Delta and Bohai Sea coastal zone are long distance and different environment with Po River Delta and Adriatic Sea coastal zone, the comparison of data of two different areas and the evolution trend of two areas are quite similar. The influence of natural climatic changes on the evolution of the deltas and coastal zones exists both in ancient and modern times. The cold/wet period occurred in 1300—1400A. D. and 1550 —1850 A.D. within this"large scale" climatie cycle, and shorter periods (10— 35 years) of cold rainy weather alternated with warm/dry period are known as "Bruckner cycles" which have influence on the evolution of the deltas and coastal zones.  相似文献