共查询到19条相似文献,搜索用时 109 毫秒
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海洋环境地球化学——Ⅱ.海水中汞的存在形态及其在海水-底质间相互交换研究 总被引:1,自引:0,他引:1
研究和测定海水中汞的存在形态和在海水-底质间的相互交换,对于探明汞在海洋中的转移变化及其最后归宿,评价海区汞的自净能力,以及防治汞对海洋的污染等均具有重要意义。 相似文献
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特征线计算格式下共轭方程两种导出途径的比较 总被引:1,自引:0,他引:1
共轭方程的导出是建立资料同化模型的关键,其导出方式有两种途径:AFD形式与FDA形式。在特征线计算格式基础上针对一类较广泛海洋动力控制方程分析了其两种共轭方程(AFD形式与FDA形式)之间的关系,并将理论结果应用于波谱共轭方程的讨论。 相似文献
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通过在海洋上混合层温度方程的平流输运项中加入Stokes漂的影响,定量计算了波浪Sokes漂对混合层温度变化的贡献,即Stokes漂对SST变化的影响。结果表明,波浪Stokes漂的平流输运作用对混合层温度变化的贡献与平均流的贡献在量值上处于可比的量级,二者全球平均比值为23.43%,最大比值达到70%。而对于SST变化率的影响也较为显著,加入Stokes漂影响后,SST变化率的最大变化值达到0.989×10-6℃/s,SST变化率的全球平均变化值为0.077 8×10-6℃/s,与SST变化率全球平均量值0.516 2×10-6℃/s相比达到15.07%,是不可忽略的。因此,在对于海洋混合层温度计算过程中,考虑波浪Stokes漂的作用是必要的。 相似文献
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机载超低频雷达探测海洋内波是海洋内波探测的新方法。海洋内波使海水电导率垂向分布发生扰动,当雷达发射的电磁波探测信号传播到内波扰动界面,电磁信号发生反射,部分反射信号再次穿透海面传播到空气中并被天线捕捉,雷达系统通过处理内波界面处的反射信号并抑制海面的反射信号实现对海洋内波的探测。根据麦克斯韦方程和海水的物理性质,推导出超低频电磁波在海水中的传播特性,研究海水温度、盐度变化对海水电导率的影响,根据KDV方程解和垂向特征函数解构造了海洋内波垂向结构,仿真了雷达接收到的海表面处、内波界面处的反射信号及其延迟时间,仿真结果表明,可以使用该方法探测海洋内波。 相似文献
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在国际上,借助于标准海水测量海水的盐度值已经沿用了八十多年的历史。在我国副标准海水(通称中国标准海水)的生产和使用也有二十多年的时间了。副标准海水在海洋调查及海洋研究中起到了统一我国盐度量值的作用。自1982年贯彻 pss—78国际实用盐标以来,中国标准海水厂经过整顿之后,产品质量有了明显的提高,现在正以每年5000瓶的产量向中国海洋界提供副标准海水。中国系列副标准海水的制备工艺在海洋技术研究所于1986年10月通过了技术鉴定,现已开始批量生产。像这样的生产规模和体翩在世界上是不多的。为了保障 相似文献
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海洋异养浮游细菌生物量及生产力的制约因素 总被引:15,自引:0,他引:15
根据海洋异养浮游细菌既是分解者,又是生产者的特点,从生态学方面探讨了海洋异养浮游细菌在海洋生态系统中的作用、研究现状及细菌生物量和生产力的制约因素。认为具有重要生态学意义的海洋异养浮游细菌生物量和生产力的主要影响因素有溶解性有机碳的性质及含量、无机营养盐浓度、海水温度、微量金属元素(如铁)含量、海洋异养浮游动物的摄食能力和噬菌体的感染等。 相似文献
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近岸局部范围内的波浪是由远处洋面上生成并传播过来的,它的生成发展源地(敏感性海域)对于所关注范围的波浪起决定性影响。共轭方程中的模式变量反映了物理参量的梯度变化,利用它可以达到精确确定敏感海域具体位置的目的。本文在LAGFD-WAM海浪模式基础上建立了海浪谱共轭方程,提出了通过在关注点邻域加一小扰动作为逆向积分海浪谱共轭方程的驱动项,来计算出梯度极值分布的思想。将这一思想应用于东中国海区域,通过一系列试验来确定舟山及长江口附近海域的敏感性区域位置。试验结果符合物理意义,梯度极值分布结果为下一步的多源卫星观测资料复合分析及最优实测方案设计奠定了基础。 相似文献
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A new method of assimilating sea surface height (SSH) data into ocean models is introduced and tested. Many features observable by satellite altimetry are approximated by the first baroclinic mode over much of the ocean, especially in the lower (but non-equatorial) and mid latitude regions. Based on this dynamical trait, a reduced-dynamics adjoint technique is developed and implemented with a three-dimensional model using vertical normal mode decomposition. To reduce the complexity of the variational data assimilation problem, the adjoint equations are based on a one-active-layer reduced-gravity model, which approximates the first baroclinic mode, as opposed to the full three-dimensional model equations. The reduced dimensionality of the adjoint model leads to lower computational cost than a traditional variational data assimilation algorithm. The technique is applicable to regions of the ocean where the SSH variability is dominated by the first baroclinic mode. The adjustment of the first baroclinic mode model fields dynamically transfers the SSH information to the deep ocean layers. The technique is developed in a modular fashion that can be readily implemented with many three-dimensional ocean models. For this study, the method is tested with the Navy Coastal Ocean Model (NCOM) configured to simulate the Gulf of Mexico. 相似文献
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海浪组成波中的四波共振时满足谱作用量、谱能量及动量守恒,在变分同化所建立的波谱共轭方程中,对应于非线性波波相互作用源函数Boltzman积分形式,本文建立了其共轭源函数满足的守恒关系;实际海浪计算时广泛采用Hasselmann et al.(1985)的参数化方法,本文给出其综合作用表示式,证明也满足谱作用量、谱能量及动量守恒,并进一步导出了其共轭源函数中存在的守恒量。所有的共轭源函数守恒量只是对共轭算子而言的,对于共轭波谱则不存在相应的守恒关系。 相似文献
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Estimation of eddy viscosity on the South China Sea shelf with adjoint assimilation method 总被引:2,自引:0,他引:2
The eddy viscosity of the ocean is an important parameter indicating the small-scale mixing process in the oceanic interior water column.Ekman wind-driven current model and adjoint assimilation technique are used to calculate the vertical profiles of eddy viscosity by fitting model results to the observation data.The data used in the paper include observed wind data and ADCP data obtained at Wenchang Oil Rig on the SCS (the South China Sea) shelf in August 2002.Different simulations under different wind conditions are analyzed to explore how the eddy viscosity develops with varying wind field.The results show that the eddy viscosity endured gradual variations in the range of 10-3-10-2 m2/s during the periods of wind changes.The mean eddy viscosity undergoing strong wind could rise by about 25% as compared to the value under weak wind. 相似文献
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Motoyoshi Ikeda 《Journal of Oceanography》2003,59(1):79-86
An approximate variational method is proposed to assimilate an oceanographic data set with a numerical ocean model. In the
approximate method, the adjoint equation to a governing equation is derived and then converted to a finite difference form,
in contrast to the ordinary, exact variational method which is composed of a finite difference equation adjoint to the finite
difference governing equation. A cumbersome derivation of the adjoint equation is avoided, and finite difference schemes used
for the original governing equation are easily utilized for the adjoint equation. This method has been verified with twin
experiments. The flow field in the twin experiments is composed of dipole eddies in a two-layer quasi-geostrophic model. Initial
and boundary conditions are control variables. The descent converges towards the exact field within 50 iterations, showing
that the fundamental problem of the method (an unstable descent with a large number of iterations) does not appear. The approximate
method is promising and should be tried with real data.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献