近海工程环境应用中各种风资料的平均时间分析   总被引：5，自引：0，他引：5  

吴增茂  孙士才 《海岸工程》1995,14(3):8-12

本文从近海工程设计应用的需要出发，对于通常使用的不同来源的测风资料平均时间进行了分析，这些资料来源包括：岸边及近海探查与生产设施上的气象台站、天气观测船、浮标、商船气象报、从受灾情况估计出的极大风速以及动力诊断模型估计出的海面风速。  相似文献   

珠江口伶仃洋锋的类别及其对沉积的影响   总被引：1，自引：0，他引：1  

应秩甫 《热带海洋学报》1994,(2)

根据近年在珠江口伶仃洋的观测资料，对比国外有关河口锋的定义，归纳了伶仃洋内几种锋的现象，计有潮侵锋、岬角锋及湖水退急时的浅滩锋等。解释了锋生的原因与潮汐进退，特别与随潮入侵的咸水关系。文中也探讨了这些锋对沉积环境的影响，认为它是陆架水入侵河口地区的一种不容忽视的沉积动力过程。  相似文献   

Temporal patterns in the structure of macrobenthic communities of an Australian estuary     

Sebastian Rainer 《Estuarine, Coastal and Shelf Science》1981,13(6):597-620

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Beneath the surface: Characteristics of oceanic ecosystems under weak mixing conditions – A theoretical investigation     

Aike Beckmann  Inga Hense   《Progress in Oceanography》2007,75(4):771-796

This study considers an important biome in aquatic environments, the subsurface ecosystem that evolves under low mixing conditions, from a theoretical point of view. Employing a conceptual model that involves phytoplankton, a limiting nutrient and sinking detritus, we use a set of key characteristics (thickness, depth, biomass amplitude/productivity) to qualitatively and quantitatively describe subsurface biomass maximum layers (SBMLs) of phytoplankton. These SBMLs are defined by the existence of two community compensation depths in the water column, which confine the layer of net community production; their depth coincides with the upper nutricline. Analysing the results of a large ensemble of simulations with a one-dimensional numerical model, we explore the parameter dependencies to obtain fundamental steady-state relationships that connect primary production, mortality and grazing, remineralization, vertical diffusion and detrital sinking. As a main result, we find that we can distinguish between factors that determine the vertically integrated primary production and others that affect only depth and shape (thickness and biomass amplitude) of this subsurface production layer. A simple relationship is derived analytically, which can be used to estimate the steady-state primary productivity in the subsurface oligotrophic ocean. The fundamental nature of the results provides further insight into the dynamics of these “hidden” ecosystems and their role in marine nutrient cycling.  相似文献   

Elucidating the dynamics and mixing agents of a shallow fjord through age tracer modelling     

Karin E. Gustafsson  Jrgen Bendtsen 《Estuarine, Coastal and Shelf Science》2007,74(4):641

The mixing agents and their role in the dynamics of a shallow fjord are elucidated through an Eulerian implementation of artificial tracers in a three-dimensional hydrodynamic model. The time scales of vertical mixing in this shallow estuary are short, and the artificial tracers are utilized in order to reveal information not detectable in the temperature or salinity fields. The fjord's response to external forcing is investigated through a series of model experiments in which we quantify vertical mixing, transport time scales of fresh water runoff and estuarine circulation in relation to external forcing.Using age tracers released at surface and bottom, we quantify the time scales of downward mixing of surface water and upward mixing of bottom water. Wind is shown to be the major agent for vertical mixing at nearly all depth levels in the fjord, whereas the tide or external sea level forcing is a minor agent and only occasionally more important just close to the bottom. The time scale of vertical mixing of surface water to the bottom or ventilation time scale of bottom water is estimated to be in the range 0.7 h to 9.0 days, with an average age of 2.7 days for the year 2004.The fjord receives fresh water from two streams entering the innermost part of the fjord, and the distribution and age of this water are studied using both ageing and conservative tracers. The salinity variations outside this fjord are large, and in contrast to the salinity, the artificial tracers provide a straight forward analysis of river water content. The ageing tracer is used to estimate transport time scales of river water (i.e. the time elapsed since the water left the river mouth). In May 2004, the typical age of river water leaving the fjord mouth is 5 days. As the major vertical mixing agent is wind, it controls the estuarine circulation and export of river water. When the wind stress is set to zero, the vertical mixing is reduced and the vertical salinity stratification is increased, and the river water can be effectively exported out of the fjord.We also analyse the river tracer fields and salinity field in relation to along estuary winds in order to detect signs of wind-induced straining of the along estuary density gradient. We find that events of down estuary winds are primarily associated with a reduced along estuary salinity gradient due to increased surface salinity in the innermost part of the fjord, and with an overall decrease in vertical stratification and river water content at the surface. Thus, our results show no apparent signs of wind-induced straining in this shallow fjord but instead they indicate increased levels of vertical mixing or upwelling during down estuary wind events.  相似文献   

河口变形效应与涌潮的形成     

杜勇 《中国海洋大学学报(自然科学版)》1989,(3)

作者采用非线性潮波方程,假定河口的宽度B(x)和深度h(x)是任意可微函数,导出了涌潮发生的条件,并讨论了各种变形情况下涌潮的形成。得出结论是,在涌潮形成过程中起决定作用的是浅水非线性效应,而河口变形效应则是起促进作用的。  相似文献   

Estimation of gillnet and hook selectivity using log-linear models   总被引：5，自引：0，他引：5  

Millar  Russell B.; Holst  Rene 《ICES Journal of Marine Science》1997,54(3):471-477

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鸭绿江洪季的河口最大混浊带   总被引：4，自引：0，他引：4  

金惜三  李炎 《海洋学研究》2001,19(1):1-10

对 1 994年 8月在鸭绿江河口的水文和悬浮泥沙的观测资料进行分析。结果表明 ,在洪季鸭绿江河口的最大混浊带 ,出现在第一个河口锋面内侧。它的核心处盐度小于 1 ,从上游带入河口的细颗粒泥沙多数被河口第一锋面截留 ,还有一部分上游来沙穿过该锋面 ,聚集在河口第一和第二锋面之间。垂向密度环流作用和絮凝作用在鸭绿江洪季最大混浊带的维持过程中起着主导作用  相似文献   

Swimming endurance of haddock (Melanogrammus aeglefinus L.) at prolonged and sustained swimming speeds, and its role in their capture by towed fishing gears     

Breen  Mike; Dyson  Jamie; O'Neill  Finbarr G.; Jones  Emma; Haigh  Michael 《ICES Journal of Marine Science》2004,61(7):1071-1079

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一类广义Sine-Gordon方程的概周期解   总被引：4，自引：0，他引：4  

朴大雄  邱汶华 《中国海洋大学学报(自然科学版)》2006,36(6):892-894

用最大值原理和Banach压缩映像原理研究一类广义Sine-Gordon方程的概周期解问题,证明概周期解的存在‖u‖L∞<π2中的唯一性。  相似文献