E1 Nio phenomenon in simple ocean data assimilation data     

GUI Maochang  *  WU Lingjuan  . Institute of Oceanology  Chinese Academy of Sciences  Qingdao  China. Laboratory of Numerical Modeling for Atmospheric Sciences  Geophysical Fluid Dynamics  Institute of Atmospheric Physics  Chine-se Academy of Sciences  Beijing  China. Graduate School  Chinese Academy of Sciences  Beijing  China 《海洋学报(英文版)》2005,(4)

1 IntroductionIt is well known that interaction between the trop-ical ocean and atmosphere produces the largest inter-annual climate signal, El Nino-Southern Oscillation(ENSO). In past decades many efforts have been madein understanding and predicting ENSO: such as the hy-pothesis of Bjerknes (1969) that ENSO arises as aself-sustained cycle in which SSTA in the Pacific O-cean causes the trade winds to strengthen or slackenand that this in turn drives the ocean circulation changesthat …  相似文献   

多传感器观测下带乘性噪声系统的逆向滤波与反褶积融合算法     

褚东升  李玉全  梁猛  张玲 《中国海洋大学学报(自然科学版)》2002,32(5):837-842

针对多传感器观测环境下带乘性噪声系统的逆向最优滤波与反褶积融合估计问题 ,本文提出了 1种基于极大似然准则的最优融合算法。该算法中各单传感器间并行计算 ,并且融合中心与单传感器处理中心间无反向通讯 ,因而执行效率较高。仿真表明 ,该融合算法产生的逆向滤波与反褶积比单传感器处理结果有较明显提高  相似文献   

珠江口洪季最大浑浊带的大小潮变化与机制分析*     

严冬  宋德海  鲍献文 《热带海洋学报》2020,39(1):20-35

基于ROMS三维模型, 模拟了珠江口洪季最大浑浊带的轴、侧向分布和大、小潮变化。模拟结果表明, 珠江口伶仃洋最大浑浊带的轴向位置在22.3°—22.45°N之间, 并随着潮流变化而周期性上下游迁移。控制最大浑浊带形成的主要因素是余流作用下的底层泥沙辐聚, 决定最大浑浊带位置的主要因素是水平对流输沙, 泥沙来源主要是上游浅滩沉积物的再悬浮。小潮期间堆积在浅滩的细颗粒沉积物在大潮期间被悬浮, 搬运到下游的滞流点位置, 在中滩南部和西滩外缘落淤。“潮泵”作用在大潮期间将泥沙向下游输运, 在小潮期间向上游输运; 垂向剪切作用则有利于悬浮泥沙的陆向输运; 二者共同作用产生泥沙辐聚, 形成最大浑浊带。大、小潮期间余流结构差异不大, 主要由密度差和潮汐混合不对称共同导致, 其中前者贡献更大。  相似文献   

Pitfalls in the estimation of wind wave directional spectra by variational principles     

Jos Ochoa  Oscar E. Delgado-Gonzlez 《Applied Ocean Research》1990,12(4):180-187

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太湖表面定振波的数值计算和最大熵谱分析   总被引：1，自引：0，他引：1  

逄勇  濮培民 《海洋与湖沼》1996,27(2):157-162

利用水动力学方程对太湖表面的定振波进行计算，算得定振波周期约为４５２ｍｉｎ，另外，利用１９９２年８月２９－３１日在太湖西山观测到的水位资料，采用最大熵谱法，分析太湖表面的定振波，得周期值约为４５０ｍｉｎ。计算和分析的周期值基本吻合，取熵谱分析结果得太湖表面的单节点定振波周期值为４５０ｍｉｎ。  相似文献   

Preliminary study on different nutrient pools supplies for the phytoplankton growth in the Jiaozhou Bay in China in the fall of 2004     

WANG Dan  SUN Jun  SONG Shuqun  LUAN Qingshan  Joey McMurdie 《海洋学报(英文版)》2007,26(3):110-120

The source and significance of two nutrients, nitrogen and phosphorous, were investigated by a modified dilution method performed on seawater samples from the Jiaozhou Bay, in autumn 2004. This modified dilution method accounted for the phytoplankton growth rate, microzooplankton grazing mortality rate, the internal and external nutrient pools, as well as nutrient supplied through remineralization by microzooplankton. The results indicated that the phytoplankton net growth rate increased in turn from inside the bay, to outside the bay, to in the Xiaogang Harbor. The phytoplankton maximum growth rates and microzooplankton grazing mortality rates were 1.14 and 0.92 d-1 outside the bay, 0.42 and 0.32 d-1 inside the bay and 0.98 and 0.62 d-1 in the harbor respectively. Outside the bay, the remineralized nitrogen (Kr=24.49) had heavy influence on the growth of the phytoplankton. Inside the bay, the remineralized phosphorus(Kr=3.49) strongly affected the phytoplankton growth. In the harbor, the remineralized phosphorus (Kr=3.73) was in larger demand by phytoplankton growth. The results demonstrated that the different nutrients pools supplied for phytoplankton growth were greatly in accordance with the phytoplankton community structure, microzooplankton grazing mortality rates and environmental conditions. It is revealed that nutrient remineralization is much more important for the phytoplankton growth in the Jiaozhou Bay than previously believed.  相似文献   

中国东海2万年来海平面变化分析   总被引：4，自引：0，他引：4  

辛立国  李广雪  李西双  马妍妍 《中国海洋大学学报(自然科学版)》2006,36(5):699-704,698

拟通过中国东海相对海平面与全球海平面对比分析，来获得东海构造沉降数据。但在对比分析的过程中发现，断裂作用对中国东海150m以深海域相对海平面的变化有重要影响。这种作用使东海150m以深海底至少下降了30m，这是我国学者先前误认为中国东海末次冰盛期最低海面位置位于现今海面下150～160m一带的主要原因。在此基础上，进一步对水与冰川重力均衡、沉积物压实和构造沉降作用进行了探讨。结果认为重力均衡不足、沉积物压实作用微弱，构造沉降是造成东海相对海平面与全球海面之间差异的又一重要原因。同时发现东海构造沉降随水深呈规律性变化。断裂作用的表现结果所赋予的更深层次的思考与认识是，在17kaB．P．以前，中国东海水深150～160m一带是1个相对隆起带，其存在对陆架区圈闭和捕获中国大陆古水系和沉积物具有重要意义。  相似文献   

针对应急救援的强余震特征统计          下载免费PDF全文

管丽倩    戴君武    杨永强    许德峰   《世界地震工程》2022,38(3):212-220

大地震后强余震活跃,震后快速判断最大余震震级和强余震发生可能性对提高应急救援效率有重大意义。针对震后应急救援,本文根据救援存活率将震后救援期分为8个时段:震后12 h、震后24 h、震后48 h、震后72 h、震后96 h、震后120 h、震后144 h和震后168 h。对我国大陆地区1966年以来6级及以上地震强余震资料进行分时段统计,分别拟合出8个时段的最大余震震级和主震震级的经验公式;并提出震后强余震发生可能性的经验判断方法,通过本文提出的可能性指数a,依据主震震级,震后可以快速判定强余震发生的可能性。  相似文献   

Identification of trends in rainfall,rainy days and 24 h maximum rainfall over subtropical Assam in Northeast India     

Deepak Jhajharia  Brijesh K. Yadav  Sunil Maske  Surajit Chattopadhyay  Anil K. Kar 《Comptes Rendus Geoscience》2012,344(1):1-13

Trends in rainfall, rainy days and 24 h maximum rainfall are investigated using the Mann-Kendall non-parametric test at twenty-four sites of subtropical Assam located in the northeastern region of India. The trends are statistically confirmed by both the parametric and non-parametric methods and the magnitudes of significant trends are obtained through the linear regression test. In Assam, the average monsoon rainfall (rainy days) during the monsoon months of June to September is about 1606 mm (70), which accounts for about 70% (64%) of the annual rainfall (rainy days). On monthly time scales, sixteen and seventeen sites (twenty-one sites each) witnessed decreasing trends in the total rainfall (rainy days), out of which one and three trends (seven trends each) were found to be statistically significant in June and July, respectively. On the other hand, seventeen sites witnessed increasing trends in rainfall in the month of September, but none were statistically significant. In December (February), eighteen (twenty-two) sites witnessed decreasing (increasing) trends in total rainfall, out of which five (three) trends were statistically significant. For the rainy days during the months of November to January, twenty-two or more sites witnessed decreasing trends in Assam, but for nine (November), twelve (January) and eighteen (December) sites, these trends were statistically significant. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the well-reported climatic warming in monsoon and post-monsoon seasons may have implications for human health and water resources management over bio-diversity rich Northeast India.  相似文献   

At‐a‐station hydraulic geometry relations, 1: theoretical development     

Vijay P. Singh  L. Zhang 《水文研究》2008,22(2):189-215

This paper, the first of two, hypothesizes that: (1) the temporal variation of stream power of a river channel at a given station with varying discharge is accomplished by the temporal variation in channel form (flow depth and channel width) and hydraulic variables, including energy slope, flow velocity and friction; (2) the change in stream power is distributed among the changes in flow depth, channel width, flow velocity, slope, and friction, depending on the boundary conditions that the channels has to satisfy. The second hypothesis is a result of the principle of maximum entropy and the theory of minimum energy dissipation or its simplified minimum stream power. These two hypotheses lead to families of at‐a‐station hydraulic geometry relations. The conditions under which these families of relations can occur in the field are discussed. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献