星载SAR浅海水下地形和水深测量模拟仿真──水下地形高度、坡度和方向与可测水深分析   总被引：7，自引：0，他引：7  

傅斌  黄韦艮  周长宝  杨劲松  史爱琴  厉冬玲 《海洋学报》2001,23(1):35-42

根据星载合成孔径雷达(SAR)浅海水下地形和水深成像机理,建立了浅海水下地形和水深雷达后向散射截面仿真模型.利用该模型模拟并分析了不同地形条件下,浅海水下地形的雷达后向散射截面.分析结果表明,水下地形高度越高,SAR可测量的水深越深;水下地形坡度越大,越易被SAR所观测.水下地形的星载SAR测量还与水下地形的方向有关,与卫星飞行方向平行的水下地形最易被SAR观测,与卫星飞行方向垂直的水下地形最不易被SAR观测.  相似文献   

渤海、黄海强温跃层数值预报模式     

王宗山  徐伯昌  金梅兵  邹娥梅  李繁华 《海洋科学进展》1996,(3)

文中对前人关于水温垂直结构计算、模拟和预报研究成果进行了评价，并在此基础上建立了考虑海面吸收辐射和透射辐射、地形、风、海流、界面摩擦及其引起的混合作用的强温跃层三维数值预报模式。该模式运行的驱动量仅为风和气温场资料，因而具有较好的实用性；此外，从试报的结果看，效果是令人满意的。  相似文献   

波浪底摩擦力对重砂富集的影响——以鲁南近岸区为例     

金秉福 《海洋科学》1997,21(5):49-52

根据浅水波浪的底摩擦效应，对鲁南灵山湾和臼－岚山镇近岸区进行了波浪的海底摩擦力计算。波浪的海底摩擦力等值图与已知滨海锆石砂矿资料对比表明，底摩擦力大于０．１８Ｎ／ｍ＾２的动力分选区有利于重矿物砂富集。据此，进一步预测了鲁南近岸带的砂矿富集区。  相似文献   

Numerical study of the meridional overturning circulation with “mixing hotspots” in the Pacific Ocean     

Takahiro Endoh  Toshiyuki Hibiya 《Journal of Oceanography》2006,62(3):259-266

Using an idealized ocean general circulation model, we examine the effect of “mixing hotspots” (localized regions of intense diapycnal mixing) predicted based on internal wave-wave interaction theory (Hibiya et al., 2006) on the meridional overturning circulation of the Pacific Ocean. Although the assumed diapycnal diffusivity in the mixing hotspots is a little larger than the predicted value, the upwelling in the mixing hotspots is not sufficient to balance the deep-water production; out of 17 Sv of the downwelled water along the southern boundary, only 9.2 Sv is found to upwell in the mixing hotspots. The imbalance as much as 7.8 Sv is compensated by entrainment into the surface mixed layer in the vicinity of the downwelling region. As a result, the northward transport of the deep water crossing the equator is limited to 5.5 Sv, much less than estimated from previous current meter moorings and hydrographic surveys. One plausible explanation for this is that the magnitude of the meridional overturning circulation of the Pacific Ocean has been overestimated by these observations. We raise doubts about the validity of the previous ocean general circulation models where diapycnal diffusivity is assigned ad hoc to attain the current magnitude suggested from current meter moorings and hydrographic surveys.  相似文献   

Structure of Subsurface Intrusion of the Oyashio Water into the Kuroshio Extension and Formation Process of the North Pacific Intermediate Water     

Kuniaki Okuda  Ichiro Yasuda  Yutaka Hiroe  Yugo Shimizu 《Journal of Oceanography》2001,57(2):121-140

In order to understand the actual formation process of the North Pacific Intermediate Water (NPIW), structure of subsurface intrusions of the Oyashio water and the mixing of the Oyashio and the Kuroshio waters in and around the Kuroshio Extension (KE) were examined on the basis of a synoptic CTD observation carried out in May-June 1992. The fresh Oyashio water in the south of Hokkaido was transported into KE region through the Mixed Water Region (MWR) in the form of subsurface intrusions along two main paths. The one was along the east coast of northern Japan through the First Branch of the Oyashio (FBO) and the other along the eastern face of a warm streamer which connected KE with a warm core ring through the Second Branch of the Oyashio (SBO). The fresh Oyashio water extended southward through FBO strongly mixed with the saline NPIW transported by the Kuroshio in the south of Japan (old NPIW) in and around the warm streamer. On the other hand, the one through SBO well preserved its original properties and extended eastward beyond 150°E along KE with a form of rather narrow band. The intrusion ejected Oyashio water lens with a diameter of 50–60 km southward across KE axis and split northward into the MWR involved in the interaction of KE and a warm core ring, which were supposed to be primary processes of new NPIW formation.  相似文献   

抑制栉孔扇贝第一极体对受精卵染色体行为及胚胎倍性组成的影响   总被引：4，自引：0，他引：4  

李永仁  阙华勇  张国范 《海洋科学》2005,29(8):66-70

采用细胞松弛素B（CB）处理，栉孔扇贝（Chlamys ferreri）抑制其受精卵的第一极体（PB1），研究抑制PB1对受精卵减数分裂过程及胚胎倍性组成的影响。结果发现，抑制第一极体显著改变了受精卵的染色体行为，在第二次减数分裂过程中共发现4种典型染色体分离类型，分别是三极分离（41．7％）、二极分离（11．7％）、双二极分离（24．9％）和非同步分离（2．8％），其余的受精卵（19．0％）染色体分离行为紊乱。对4-8细胞期胚胎的倍性组成进行分析，发现处理组中含有二倍体（10．9％）、三倍体（12．5％）、四倍体（19.5％）、五倍体（12．6％）以及非整倍体（46．6％）胚胎。研究结果表明，二极分离和双二极分离分别是形成三倍体和四倍体的主要机制，而其他的染色体分离行为将主要形成非整倍体。  相似文献   

Risk Assessment for Tuzla Naval Base Breakwater   总被引：5，自引：0，他引：5  

Can Elmar BALAS 《中国海洋工程》2003,17(3)

1 .IntroductionTurkeywasstruckbytwomajorearthquakeeventsonAugust 1 7thandNovember 1 2th ,1 999,namedIzmit (Mw=7.4 )andD櫣ｚｃｅ (Mw=7.2 )earthquakes,respectively .ThestationsoperatedbytheGeneralDirectorateofDisasterAffairs,theKandilliObservatoryandEarthquakeResearchInstituteofIstanbulTechnicalUniversitymeasuredatleast 2 7stronggroundmotionsfortheIzmitearthquakewithin 2 0 0kmofthefault.AsignificantsegmentofthefaultrupturedintheareabetweenthewestofGolcukandtheeastofLakeSapanca .Inthesou…  相似文献   

Model simulations of carbon sequestration in the northwest Pacific by patch fertilization     

Katsumi Matsumoto 《Journal of Oceanography》2006,62(6):887-902

Iron fertilization of nutrient-rich surface waters of the ocean is one possible way to help slow the rising levels of atmospheric CO₂ by sequestering it in the oceans via biological carbon export. Here, I use an ocean general circulation model to simulate a patch of nutrient depletion in the subpolar northwest Pacific under various scenarios. Model results confirm that surface fertilization is an inefficient way to sequester carbon from the atmosphere (Gnanadesikan et al., 2003), since only about 20% of the exported carbon comes initially from the atmosphere. Fertilization reduces future production and thus CO₂ uptake by utilizing nutrients that would otherwise be available later. Effectively, this can be considered as leakage when compared to a control run. This “effective” leakage and the actual leakage of sequestered CO₂ cause a significant, rapid decrease in carbon retention (only 30–45% retained after 10 years and less than 20% after 50 years). This contrasts markedly with the almost 100% retention efficiency for the same duration using the same model, when carbon is disposed directly into the northwest Pacific (Matsumoto and Mignone, 2005). As a consequence, the economic effectiveness of patch fertilization is poor in two limiting cases of the future price path of carbon. Sequestered carbon in patch fertilization is lost to the atmosphere at increasingly remote places as time passes, which would make monitoring exceedingly difficult. If all organic carbon from one-time fertilization reached the ocean bottom and remineralized there, acidification would be about −0.05 pH unit with O₂ depletion about −20 μmol kg⁻¹. These anomalies are probably too small to seriously threaten deep sea biota, but they are underestimated in the model because of its large grid size. The results from this study offer little to advocate purposeful surface fertilization as a serious means to address the anthropogenic carbon problem.  相似文献   

Modified PIC Method for Sea Ice Dynamics   总被引：1，自引：0，他引：1  

王瑞学  季顺迎SHEN Hung-tao 岳前进 《中国海洋工程》2005,19(3):457-468

The sea ice cover displays various dynamical characteristics such as breakup, rafting, and ridging under external forces. To model the ice dynamic process accurately, the effective numerical modeling method should be established. In this paper, a modified particle-in-cell （PIC） method for sea ice dynamics is developed coupling the finite difference （FD） method and smoothed particle hydrodynamics （SPH）. In this method, the ice cover is first discretized into a series of lagrangian ice particles which have their own sizes, thicknesses, concentrations and velocities. The ice thickness and concentration at Eulerian grid positions are obtained by interpolation with the Gaussian function from their surrounding ice particles. The momentum of ice cover is solved with FD approach to obtain the Eulerian cell velocity, which is used to estimate the ice particle velocity with the Gaussian function also. The thickness and concentration of ice particles are adjnsted with particle mass density and smooth length, which are adjusted with the redistribution of ice particles. With the above modified PIC method, numerical simulations for ice motion in an idealized rectangular basin and the ice dynamics in the Bohai Sea are carried out. These simulations show that this modified PIC method is applicable to sea ice dynamics simulation.  相似文献   

波峰特征量的统计分布     

张寒元  于定勇 《中国海洋大学学报(自然科学版)》2003,33(6):989-997

本文在作者另文数值模拟得到的三维海浪基础上 ,进一步分析给出了三维波峰长度、高度及方向角度等特征量的统计分布。发现考虑海浪的方向性质后波峰分布不再是均匀连续的 ;波峰的长度分布受方向函数影响 ,方向分布越宽 ,波峰的平均长度越短 ,波峰的方向角分布越宽 ;波峰高度和长度在波峰高度较小时有很大的相关性 ,而在波峰高度很大时无关  相似文献