Comparison between zooplankton data collected by the Continuous Plankton Recorder survey in the English Channel and by WP-2 nets at station L4, Plymouth (UK)     

Eurgain H. John  Sonia D. Batten  Roger P. Harris  Graeme C. Hays 《Journal of Sea Research》2001,46(3-4)

Zooplankton sampling has been carried out by the Continuous Plankton Recorder (CPR) survey since the 1930s enabling the study of long-term changes in plankton populations, the elucidation of seasonal patterns of abundance, and more recently providing zooplankton biomass estimates for ecosystem models. Data for zooplankton abundance collected by CPR tows in the Western English Channel (between 1988 and 1998) were compared to vertically integrated samples collected from station L4 off Plymouth, UK. Comparisons were made for locally abundant copepods (including Acartia, Calanus, Para/Pseudocalanus, Centropages, Oithona and Temora) collected by CPR and WP-2 nets. All dominant species recorded at L4 were also common to the CPR data. However, the position of the taxa in the two datasets was not equivalent. Seasonal cycles revealed by CPR data were significantly similar to those recorded throughout the water column at L4 for most taxa. However, absolute levels of abundance differed for the two datasets: abundances were underestimated by CPR samples when compared to those of vertically integrated samples by a factor of between 2 and 35, with the exception of Centropages. The differing mesh sizes (200 and 270 μm) of the WP-2 net and CPR mesh could only partially explain these differences in abundance, implying that the behaviour of individual taxa and their depth in the water column also influenced the abundance recorded.  相似文献   

基于ArcEngine的数字高程模型更新方法研究   总被引：1，自引：0，他引：1  

施永胜  邹峥嵘  孙鸿睿 《海洋测绘》2006,26(1):50-53

采用COM技术,以ARCENGINE所提供的类库和凸包算法,实现了数字高程模型(DEM)数据更新的边界检测和利用矢量地形数据采集更新数字高程模型数据的方法。保证了数字高程模型数据的精度,可以满足数字高程模型的现势性需求。  相似文献   

A Numerical Study on the Structure and Dynamics of Turbulence in Oscillatory Bottom Layer Flow over A Flat or Rippled Bed     

白玉川  吴朝安黄涛 《中国海洋工程》2006,20(1):45-60

1 .IntroductionUnder the influence of surface waves ,sandripples often appear on beaches . Whenthe amplitudeof water oscillationis sufficientlylarge ,vortices are formed onthe lee of every sand ripple crest . A-mongthese vortices ,the most important are t…  相似文献   

胶州湾三维变动边界的潮流数值模拟   总被引：35，自引：3，他引：35  

孙英兰  张越美 《海洋与湖沼》2001,32(4):355-362

基于Blumberg等（1986）的河口、陆架和海洋模式，引入变边界处理技术，建立了胶州湾三维变动边界的潮流模型，模型以σ-正交曲线坐标下三维非线性潮波方程为基本方程，引入2.5阶瑞封闭方程组，采用分裂算子法数值求解方程组，利用湍封闭方程求解垂直紊动粘滞系数，采用干湿网格方法模拟潮流漫滩过程，三维变动边界潮流模型计算结果与实测值吻合良好。  相似文献   

闽江口水动力和污染扩散数值模拟   总被引：3，自引：0，他引：3  

江毓武  张珞平 《台湾海峡》1997,16(2):169-173

本文建立了闽江口二维水动力、污染扩散数值模型，模型采用ＡＤＩ双向隐式求解。在水动力模拟中，对岸界的丁坝有用线性边界进行拟合，并考虑到河口区侧向摩擦作用；在污染扩散模拟中，用动态拟合的方法对浓度水边界进行了较为合理的改进。计算结果表明，本模型是成功的。  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   

分潮波模型多资料数值计算方法研究　Ⅰ.岸边资料运动学外推的第一边值方法     

潘文波  孙文心 《中国海洋大学学报(自然科学版)》1996,(1)

对于含多资料三维分潮波模型建立了一种岸边资料运动学外推的潮波第一边值方法，并对渤海的四大原湖波进行试算。结果证实本方法可行，该方法使潮波方程既满足第一边值问题，充分利用岸边测站资料，又保证岸界法向流速为零条件，符合物理意义。并对复型病态矩阵的收敛问题提出了一种可行性处理。  相似文献   

龙口的海风及其影响   总被引：4，自引：0，他引：4  

薛德强  赵绪孔 《海洋湖沼通报》1995,(3):1-9

本文运用龙口气象站近５年自记风资料及实测探空资料，分析了龙口海风的生消规律、海风强度、空间结构及海风生成后对温、湿度的影响。同时为分析海风环流对大气污染物的影响。本文提出了一个简单地计算热内边界层的方法。  相似文献   

ENSO对天目山柳杉树轮同位素的影响   总被引：8，自引：0，他引：8  

陈宝君  钱君龙  濮培民 《海洋地质与第四纪地质》2002,22(4):53-58

在Nin↑～o3,4区SST序列和Jones等的SOI序列基础上，通过主分量分析方法建立了一个ENSO指数序列。并与根据天目山柳杉树轮碳，氢同位素组成比所建立的树轮指数序列进行相关分析。结果表明，天目山树轮指数与ENSO指数有很好的相关性，尤其与前2年的ENSO指数相关显著。说明ENSO对该地区树木的生长和同位素的分馏有影响，也说明天目山地区的树木年轮对于ENSO事件具有一定的记录能力。  相似文献   

Modified mild slope equation and open boundary conditions     

M. C. Khellaf  M. Bouhadef 《Ocean Engineering》2004,31(13):1713-1723

A numerical model to compute wave field is developed. It is based on the Berkhoff diffraction-refraction equation, in which an energy dissipation term is added, to take into account the breaking and the bottom friction phenomena. The energy dissipation function, by breaking and by bottom friction, is introduced in the Berkhoff equation to obtain a new equation of propagation.The resolution is done with the hybrid finite element method, where lagrangians elements are used.  相似文献