Dynamic properties of green water event in the overtopping of extreme waves on a fixed dock     

Nobuhito Mori  Daniel T. Cox 《Ocean Engineering》2003,30(16):2021-2052

A statistical model is developed to predict wave overtopping volume and rate of extreme waves on a fixed deck. The probability density function for the volume and rate of overtopping water are formulated based on the truncated Weibull distribution with the assumption of local sinusoidal profile for small amplitude waves. Sensitivity to the wave nonlinearity parameter and deck clearance is discussed. The statistical model is compared to laboratory data of the instantaneous free surface elevation measured in front of a fixed deck, and overtopping volume and overtopping rate measured at the leading edge of the deck. The statistical theory compared well with the measured exceedance probability seaward of the deck. The model prediction of the exceedance probability of deck overtopping gave qualitatively good agreement for large overtopping values.  相似文献   

斜带髭鲷幼鱼生长和生态转换效率的研究     

刘丽华  杨圣云  冯洁娉  陈明茹 《台湾海峡》2005,24(1):109-114

在实验室内, 22. 5±0. 5℃条件下以去头去骨去鳞片去皮的金色小沙丁鱼的纯肉糜为饵料饲养斜带髭鲷幼鱼,测定体重范围在 4. 6~6. 5g的斜带髭鲷的体重、体长的生长曲线及其生态转换效率和特定生长率.实验结果表明,斜带髭鲷的体重、体长在实验期间直线增长,体重、体长的生长曲线分别为Wt(w.w.湿重,下同 ) =0. 391 7t 5. 766 2(R=0. 999 6)和Lt=0. 105t 6. 265(R=0. 989 9).用胃含物法测定斜带髭鲷的胃排空率、日摄食量、日生长量、生态转换效率和特定生长率.实验得到斜带髭鲷消化道的瞬时排空率Rt= 1. 23 4×10-3 (m/m) /h,日摄食量Cd= 1. 342 9g(w.w. ),生态转换效率Eg=29. 50% ±2. 77% [m/m(w.w. ) ],特定生长率SGR=4. 71%±0. 69% [m/m(w.w. ) ].  相似文献   

太平洋海域海平面变化的灰色系统分析   总被引：3，自引：1，他引：3  

左军成  陈宗镛  戚建华 《中国海洋大学学报(自然科学版)》1997,(2)

应用灰色系统理论，对太平洋海域４８个长期验潮站的月均海平面分别建立了ＧＭ（１，１）模型。ＧＭ（１，１）模型能较好地反映太平洋海域的海平面变化的趋势，它除了能给出连续的海平面变化速率外，同时能方便地给出海平面变化的加速率。模拟结果表明，在太平洋地壳均衡假设下，太平洋海域的月均海平面以平均速率０．１７ｃｍ／ａ上升。在太平洋海域所取的４８个长期验潮站中，有４０个站在加速上升，全部站的平均加速度为０．０００２９ｃｍ／ａ２。且加速率逐渐增大。当然这些加速率都很小，但作为一种普遍性的趋势，这已足以说明：太平洋海域的海平面在加速上升  相似文献   

Scattering of Semidiurnal Internal Kelvin Wave at Step Bottom Topography     

Yuji?KawamuraEmail author  Yujiro?Kitade  Masaji?Matsuyama 《Journal of Oceanography》2005,61(1):59-68

A three-dimensional, multi-level model was used to study the energy dissipation of semidiurnal internal Kelvin waves due to their interaction with bottom topography. A simplified topography consisting of a channel with an additional shallow bay was used to clarify the wave’s scattering process. When the first mode semidiurnal internal wave given at an open boundary arrives at the bay mouth, higher-mode internal waves are generated at a step bottom of the bay mouth. As a result, the energy of the first mode internal Kelvin wave is effectively decayed. The decay rate of the internal Kelvin wave depends on both the width and length of the additional bay. The maximum decay rate was found when a resonance condition occurs the bay, that is, the bay length is equal to a quarter of wave length of the first mode internal wave on the shallow region. The decay rate in the wide bay cases is higher than that in a narrow case, due to a contribution from the scattering due to the Poincare wave that emanates from the corners of the bay head. The decay rate with the additional bay is 1.1–1.8 times that of the case without the additional bay. The decay rate due to the scattering process is found to be of the same order as that of the internal and bottom friction.  相似文献   

厦门港浮游植物对磷酸盐吸收速率的研究   总被引：12，自引：1，他引：12  

洪华生  戴民汉  黄邦钦  李文权 《海洋与湖沼》1994,25(1):54-59

用无载体32P同位素示踪测定海水中浮游植物和细菌吸收磷酸盐速率的方法，对厦门港浮游植物和细菌进行了研究。结果表明，厦门港海水中吸收磷酸盐的主体是浮游植物（几乎占100％），平均吸收速率为4．28×10－5μmol／（L·s），并且存在着晚秋＜冬＜初春的季节变化，培养实验的结果表明吸收速率的季节变化主要是由于种类更替和温度效应所致。  相似文献   

Rifting to Spreading Process along the Northern Continental Margin of the South China Sea   总被引：7，自引：0，他引：7  

Kido  Yukari  Suyehiro  Kiyoshi  Kinoshita  Hajimu 《Marine Geophysical Researches》2001,22(1):1-15

Understanding the development from syn-rift to spreading in the South China Sea (SCS) is important in elucidating the western Pacific's tectonic evolution because the SCS is a major tectonic constituent of the many marginal seas in the region. This paper describes research examining the transition from rifting to spreading along the northern margin of the SCS, made possible by the amalgamation of newly acquired and existing geophysical data. The northernmost SCS was surveyed as part of a joint Japan-China cooperative project (JCCP) in two phases in 1993 and 1994. The purpose of the investigation was to reveal seismic and magnetic characteristics of the transitional zone between continental crust and the abyssal basin. Compilation of marine gravity and geomagnetic data of the South China Sea clarify structural characteristics of its rifted continental and convergent margins, both past and present. Total and three component magnetic data clearly indicate the magnetic lineations of the oceanic basin and the magnetic characteristics of its varied margins. The analyses of magnetic, gravity and seismic data and other geophysical and geological information from the SCS led up to the following results: (1) N-S direction seafloor spreading started from early Eocene. There were at least four separate evolutional stages. Directions and rates of the spreading are fluctuating and unstable and spreading continued from 32 to 17 Ma. (2) The apparent difference in the present tectonism of the eastern and western parts of Continent Ocean Boundary (COB) implies that in the east of the continental breakup is governed by a strike slip faulting. (3) The seismic high velocity layer in the lower crust seems to be underplated beneath the stretched continental crust. (4) Magnetic anomaly of the continental margin area seems to be rooted in the uppermost sediment and upper part of lower crust based on the tertiary volcanism. (5) Magnetic quiet zone (MQZ) anomaly in the continental margin area coincides with COB. (6) The non-magnetic or very weakly magnetized layer is probably responsible for MQZ. One of the causes of demagnetization of the layer is due to hydrothermal alteration while high temperature mantle materials being underplated. Another explanation is that horizontal sequences of basalt each with flip-flop magnetization polarity cancel out to the resultant magnetic field on the surface. We are currently developing a synthetic database system containing datasets of seismicity, potential field data, crustal and thermal structures, and other geophysical data to facilitate the study of past, contemporary and future changes in the deep sea environment around Japan; i.e. trench, trough, subduction zones, marginal basins and island arcs. Several special characteristics are an object-oriented approach to the collection and multi-faceted studies of global data from a variety of sources.  相似文献   

Fishing, selection, and phenotypic evolution   总被引：10，自引：9，他引：10  

Law  Richard 《ICES Journal of Marine Science》2000,57(3):659-668

  相似文献   

Sensitivity to stress of the estuarine bivalve Macoma balthica from areas between the Netherlands and its southern limits (Gironde)     

H. Hummel  C. Amiard-Triquet  G. Bachelet  M. Desprez  J. Marchand  B. Sylvand  J.C. Amiard  H. Rybarczyk  R.H. Bogaards  J. Sinke  Y. De Wit  L. De Wolf 《Journal of Sea Research》1996,35(4):315-321

Variation in the sensitivity to stress of Macoma balthica was measured in several French and Dutch estuaries. For adult and juvenile Macoma balthica exposed to copper under conditions of starvation, differences in mortality rate, condition, glycogen, burrowing rate and copper content were assessed. No significant differences were observed between adults and juveniles; the influence of treatment and origin was always evident. Animals from the most southern estuaries, Loire and Gironde, near to the species's southern limit of distribution, showed, in the field, the strongest deviations for the ecophysiological traits measured, and were in the experiments the most sensitive to stress.  相似文献   

高精度新方法测量计算船舶磁场分布     

陈芸  赵培聪  顾新宏  曹全林  罗法贵  王硕儒 《海洋与湖沼》1995,26(5):480-487

将高精度质子磁探仪和位场变换理论用于测量计算船舶磁场，以研究其在海洋中的分布。由质子磁探仪实测海面上１０ｍ处磁场的模（船的磁场与地磁场矢量的和的绝对值），用位场变换理论计算出船的磁场三个分量在水面和水下的分布；并采用一系列有效措施，提高计算速度和结果的精度。将该方法和磁球理论严格解比较，在ｚ＝０面上误差小于０．１％，在ｚ＝－２０ｍ面上误差小于１％；还给出船的磁场强度在船的纵横向的分布曲线和平面立体  相似文献   

三峡及邻区晚第三纪以来构造应力场特征探讨     

贾永刚  单红仙 《海洋科学》1995,19(2):36-41

用三峡及邻区（东经１０８°～１１３°，北纬２９°～３３°）地质资料，地震资料，现 场地应力测量资料论证三峡及邻区晚第三纪以来构造应力场稳定性及其分区特 征。  相似文献