北太平洋副热带模态水形成区潜沉率的年际变化及其机制     

胡海波  刘秦玉  刘伟 《海洋学报》2006,28(2):22-28

根据Huang和Qiu 1995年的潜沉率计算公式,采用同化的海洋模式资料和海洋-大气界面的通量观测资料,计算了北太平洋副热带海域3个模态水形成区逐年的潜沉率,研究了潜沉率产生年际变化的机制.研究结果表明:西部、中部和东部3个模态水形成区潜沉率的年际变化主要周期分别为6,2~5和2 a;北太平洋副热带模态水的3个形成区的潜沉率都发现年代际的变化特征:在1985年以前,西部模态水形成区的潜沉率年际变化最为显著,但1985后年际变化振幅明显减小;在中部模态水形成区,1975~1992年间潜沉率随时间的变化的振幅较大,潜沉率在这段时间内的平均值也达到33.99 m/a,而在1970~1975年间和1993~1998年间潜沉率都小于20 m/a;西部副热带模态水形成区的潜沉率的年际变化与这里海面的净热通量的年际变化有很好的相关性,中部副热带模态水形成区潜沉率的年际变化则取决于局地Ekman流的年际变化,而在东部模态水形成区局地风应力旋度的变化直接影响潜沉率的大小.  相似文献   

A linear Boltzmann equation to model wave scattering in the marginal ice zone   总被引：1，自引：0，他引：1  

Michael H. Meylan  Diane Masson   《Ocean Modelling》2006,11(3-4):417-427

We present a linear Boltzmann equation to model wave scattering in the Marginal Ice Zone (the region of ocean which consists of broken ice floes). The equation is derived by two methods, the first based on Meylan et al. [Meylan, M.H., Squire, V.A., Fox, C., 1997. Towards realism in modeling ocean wave behavior in marginal ice zones. J. Geophys. Res. 102 (C10), 22981–22991] and second based on Masson and LeBlond [Masson, D., LeBlond, P., 1989. Spectral evolution of wind-generated surface gravity waves in a dispersed ice field. J. Fluid Mech. 202, 111–136]. This linear Boltzmann equation, we believe, is more suitable than the equation presented in Masson and LeBlond [Masson, D., LeBlond, P., 1989. Spectral evolution of wind-generated surface gravity waves in a dispersed ice field. J. Fluid Mech. 202, 111–136] because of its simpler form, because it is a differential rather than difference equation and because it does not depend on any assumptions about the ice floe geometry. However, the linear Boltzmann equation presented here is equivalent to the equation in Masson and LeBlond [Masson, D., LeBlond, P., 1989. Spectral evolution of wind-generated surface gravity waves in a dispersed ice field. J. Fluid Mech. 202, 111–136] since it is derived from their equation. Furthermore, the linear Boltzmann equation is also derived independently using the argument in Meylan et al. [Meylan, M.H., Squire, V.A., Fox, C., 1997. Towards realism in modeling ocean wave behavior in marginal ice zones. J. Geophys. Res. 102 (C10), 22981–22991]. We also present details of how the scattering kernel in the linear Boltzmann equation is found from the scattering by an individual ice floe and show how the linear Boltzmann equation can be solved straightforwardly in certain cases.  相似文献   

Multi-scale spatial variability in fish assemblages associated with Posidonia oceanica meadows in the Western Mediterranean Sea     

Joan Moranta  Miquel Palmer  Gabriel Morey  Ana Ruiz  Beatriz Morales-Nin 《Estuarine, Coastal and Shelf Science》2006,68(3-4):579

  相似文献   

Atmospherically-promoted photosynthetic activity in a well-mixed ecosystem: Significance of wet deposition events of nitrogen compounds   总被引：1，自引：0，他引：1  

C. Boulart  P. Flament  V. Gentilhomme  K. Deboudt  C. Migon  F. Lizon  M. Schapira  A. Lefebvre 《Estuarine, Coastal and Shelf Science》2006,69(3-4):449

Wet atmospheric deposition of dissolved N, P and Si species is studied in well-mixed coastal ecosystem to evaluate its potential to stimulate photosynthetic activities in nutrient-depleted conditions. Our results show that, during spring, seawater is greatly depleted in major nutrients: Dissolved Inorganic Nitrogen (DIN), Dissolved Inorganic Phosphorus (DIP) and Silicic acid (Si), in parallel with an increase of phytoplanktonic biomass. In spring (March–May) and summer (June–September), wet atmospheric deposition is the predominant source (>60%, relative to riverine contribution) for nitrates and ammonium inputs to this N-limited coastal ecosystem. During winter (October–February), riverine inputs of DIN predominate (>80%) and are annually the most important source of DIP (>90%). This situation allows us to calculate the possibility for a significant contribution to primary production in May 2003, from atmospheric deposition (total input for DIN ≈300 kg km⁻² month⁻¹). Based on usual Redfield ratios and assuming that all of the atmospheric-derived N (AD-N) in rainwater is bioavailable for phytoplankton growth, we can estimate new production due to AD-N of 950 mg C m⁻² month⁻¹, during this period of depletion in the water column. During the same episode (May 2003), photosynthetic activity rate, considered as gross primary production, was estimated to approximately 30 300 mg C m⁻² month⁻¹. Calculation indicates that new photosynthetic activity due to wet atmospheric inputs of nitrogen could be up to 3%.  相似文献   

A probability distribution for depth-limited extreme wave heights in a sea state     

Fernando J. Mndez  Sonia Castanedo 《Coastal Engineering》2007,54(12):878-882

A model for the depth-limited distribution of the highest wave in a sea state is presented. The distribution for the extreme wave height is based on a probability density function (pdf) for depth-limited wave height distribution for individual waves [Méndez, F.J., Losada, I.J., Medina, R. 2004. Transformation model of wave height distribution. Coastal Eng, Vol. 50, 97:115.] and considers the correlation between consecutive waves. The model is validated using field data showing a good representation of the extreme wave heights in the surf zone. Some important statistical wave heights are parameterized obtaining useful expressions that can be used in further calculations.  相似文献   

马里亚纳海槽扩张轴(中心)玄武岩铂族元素特征   总被引：2，自引：0，他引：2  

曹志敏  安伟  周美夫  郑建斌  漆亮 《海洋学报》2006,28(5):69-75

马里亚纳海槽扩张轴中心玄武岩铂族元素(PGE)总量变化范围为0.418×10-9~1.022×10-9,其原始地幔标准化配分模式呈正倾斜型,表现出PPGE(包括Pt,Pd,Rh)和金的相对富集.与其他幔源岩石相比,该区玄武岩PGE总量较低,(Pd/Ir)N,(Pd/Pt)N,(Pd/Ru)N变化较大,表现出铂、铱的相对亏损和明显的铂负异常(Pt/Pt*=0.01~0.15).PGE的分布特征一方面反映了该区地幔熔融度不高,另一方面,大离子亲石元素LILE(铷、锶、钾等)、铅和轻稀土LREE略富集,暗示扩张中心之下的软流圈地幔源受到了岛弧地幔的混染.上述特征反映了马里亚纳海槽玄武岩是MORB型与岛弧型地幔源不同程度混合后部分融熔的产物.  相似文献   

关于修改港工钢筋混凝土规范小偏心受压构件正截面强度计算的建议     

王清湘 《海洋工程》1995,(2)

本文提出在小偏心受压构件正截面强度计算中，取消弯曲抗压强度ｆｃｍ（Ｒｗ），采用轴心抗压强度ｆｃ，这与构件的实际破坏形态相符。对小偏心受压构件正截面强度计算提出了设计建议。特别是对工程上大量应用的矩形截面对称配筋小偏压构件提示了简捷的设计方法，与以往的近似计算方法相比具有物理概念明确，精度高，方法简捷的特点。  相似文献   

Seasonal DOC accumulation in the Black Sea: a regional explanation for a general mechanism   总被引：2，自引：0，他引：2  

Gustave Cauwet  Gaëlle Dliat  Anton Krastev  Galina Shtereva  Sylvie Becquevort  Christiane Lancelot  Andr Momzikoff  Alain Saliot  Adriana Cociasu  Lucia Popa 《Marine Chemistry》2002,79(3-4)

During three cruises in the Black Sea, organised in July 1995 and April–May 1997, biological and chemical parameters that can influence the carbon budget were measured in the water column on the NW shelf, particularly in the mixing zone with Danube River waters. We observed in early spring (end of April–May) conditions an important input of freshwater organisms that enhanced the microbial activity in the low salinity range. High bacterial activity regenerates nitrogen in the form of nitrates, but is also responsible for an important consumption of ammonium and phosphate, leading to a high N/P ratio and a strong deficit in phosphorus. The consequence is a limitation of phytoplankton development but also a production of carbohydrates that accumulate all along the salinity gradient. These mechanisms are responsible for a seasonal accumulation of dissolved organic carbon (DOC) that increases from 210 μM in winter to about 280 μM in summer. All this excess DOC disappears during winter, probably degraded by bacterial activity. The degradation of carbon-rich organic matter increases the phosphorus demand by bacteria bringing limitation to phytoplankton primary production.  相似文献   

鲁苏榴辉岩的地球化学     

韩宗珠 《中国海洋大学学报(自然科学版)》1994,(1)

以微量元素、稀土元素、Ｓｒ和Ｎｄ同位素变异特征为依据，确定鲁苏榴辉岩为多成因、多来源和多阶段，指出主要是在印支期扬子陆块与华北陆块碰撞造山作用过程中，挤入的上地幔碎片以及不同原岩类型的壳内高压变质岩碎块。燕山晚期的区域构造热事件使得某些榴辉岩的同位素体系再平衡。  相似文献   

Quantizing and analyzing the feature information of coastal zone based on high-resolution remote sensing image     

YANG Xiaomei  LAN Rongqin  LUO Jiancheng 《海洋学报(英文版)》2006,25(6):33-42

1Introduction With the development and application of remotesensing technology, people fromthe international re-mote sensing community have realized the issue thatwe have immoderately emphasized characteristics ofvast volume data and great detail of remot…  相似文献