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利用合成孔径雷达(SAR)图像研究海洋内波具有其他遥感探测及实地海洋测量不可替代的优势,然而从SAR数据中提取内波参数的方法却往往由于人工选取的位置不同使得反演的内波参数产生不同的偏差,为了尽量避免人工操作带来的误差并有效反演内波参数,文中提出了一种SAR图像海洋内波波向与波长参数估计的新方法。通过人工选取内波前导线上的3个位置点,计算机自动地获取内波的位置和内波的波向,提取内波断面,在此基础上利用EMD算法反演内波波长,结合内波区域海水密度剖面数据,进一步反演内波振幅参数。通过对实测SAR图像数据进行处理的结果可知,采用该方法对内波SAR图像进行处理,能很好地定位内波位置并获得传播方向及内波波长参数,结合海水密度剖面,实现了内波振幅参数反演。人工干预选取3个位置点,自动计算内波前导线弯曲弧度并自动计算5个内波剖面,减少了由于人工干预操作不同形成的偏差。 相似文献
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黄磊 《海洋与海岸带开发》2014,(1):54-56
本研究探讨以多波束系统追踪海洋内波的实施方法,通过多波束系统以预定水声节点观测的海底地貌变化,追踪海洋内波引起的等温面和等密度面的相应变化,达成海洋内波的实时观测。 相似文献
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内波是层结海洋中普遍存在的一种海洋动力学现象,包含内潮、内孤立波、近惯性内波等多种形式,由于其携带能量巨大,分布范围广,发生频率高,对海洋结构物造成严重威胁。对国内外关于内波生成、传播演化、海遥感观测及其与海洋结构物相互作用方面的研究进展进行综述。总结了关于内波的生成机制、浅水和深水区域内波传播演化特征、实际海洋内波特征的遥感观测以及内波与海洋平台及水下潜器相互作用的研究成果,讨论了数值模拟、模型试验、遥感观测等研究手段在海洋内波研究中的应用以及取得的相应研究成果。最后,在探讨海洋内波研究趋势的基础上对未来关于内波生成机制及其海洋学特征观测相关研究需考虑和解决的问题进行了展望。 相似文献
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浅海内波及声场起伏数值研究 总被引：2，自引：0，他引：2
为探讨声学方法监测(反演)海洋内波的可行性,分析ASIAEX2001亚洲海海洋声学实验定点温度链实验数据,结果表明：实验期间存在M2内潮波、周期10～30min非线性内波现象,并观测到双温跃层同相传播“双非线性内波”。分别对垂直和平行于内波传播方向传播声场进行了数值计算分析。垂直于内波传播方向的声传播计算结果表明：简正波波数时间演化函数的频谱与内波引起的声速剖面变化频谱基本一致;简正波系数(模值)时间演化函数的频谱与内波引起的声源位置处的声速演化函数的频谱基本一致;高阶简正波波数差随时间的变化要比低阶简正波波数差小约1个量级。平行于内波传播方向的声传播计算结果表明：内潮波主要导致相邻简正波间耦合;非线性内波包能够导致跨号甚至垮多号简正波间耦合。讨论了2种海洋内波声学监测方法。 相似文献
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我国内波研究取得新进展 总被引：1，自引：0，他引：1
海洋内波是在海洋内部密度不均匀水层间发生的一种波动。内波像海面波浪一样常在。只要海水密度稳定分层。再有扰动源存在,内波就会产生。内波与表面波浪虽都是液体波动,但有根本不同。空气与水的密度差有好几百倍,表面波受重力影响大,因此不易形成大浪,振幅10米以上的大浪极少见。但海洋内部海水密度 相似文献
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海洋内波对水声场的扰动 总被引：4，自引：0，他引：4
针对海洋内波对水声传播影响的问题，在简要引出内波方程，水声方程和内波解，射线理论之后，以水深2100m等Vaisala频率的全板造波内波解对双线性水声剖面情况计算了内波和内波对声场及声线传播的影响，结果表明，内波对声线传播的路径和时间的影响是不可忽略的。 相似文献
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Viacheslav G. Makarov Oleg V. Zaytsev Valentina D. Budaeva Felipe Salinas-Gonzalez 《Journal of Oceanography》2008,64(5):675-690
A unified method of approximation, extrapolation, and objective layering is offered for processing vertical oceanographic
profiles. The method is demonstrated using seawater density and consists of adjustable splitting of each individual profile
into N vertical layers based on tentative, piecewise linear homogeneous approximation with specified accuracy and a final fitting
of an N-layered analytical model to data. A set of 3N coefficients of the model includes one density value at the sea surface; N−1 depths of layer interfaces; and N pairs of coefficients that describe a profile shape within the n-th layer—an asymptotic density value (a key parameter for extrapolation) and a vertical scale of maximum density variability
(related to vertical gradient). Several distinctive characteristics of the technique are: (1) It can be used for the analysis
of the vertical structure of individual profiles when N is an unknown parameter, and spatial interpolation when N should be equal for all profiles. (2) A justified downward extrapolation of incomplete data is possible with the model, especially
if historical deepwater profiles are available. (3) Layer interfaces, as well as other coefficients, are derived with only
one fitting to the entire profile. (4) The technique, using its general formulation, can serve as a parent for developing
various types of models. The simpler step-like (with hyperbolic or exponential approximation) and more complicated smooth
(continuous in gradient space) models were designed and tested against a large number of density profiles from the Sea of
Okhotsk and the Gulf of California. Comparison of parametric, z-levels and isopycnal averaging was done for the region off the northeastern coast of Sakhalin. 相似文献
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ＥｆｆｅｃｔｓｏｆｈｅｘａｖａｌｅｎｔｃｈｒｏｍｉｕｍｏｎｅａｒｌｙｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｂａｙｓｃａｌｌｏｐＡｒｇｏｐｅｃｔｅｎｉｒｒａｄｉａｎｓＬａｍａｒｃｋＩＮＴＲＯＤＵＣＴＩＯＮＣｈｒｏｍｉｕｍｉｓｗｉｄｅｌｙｕｓｅｄｉｎｔｈｅｉｎ... 相似文献
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Realistic representation of sea ice in ocean models involves the use of a non-linear free-surface, a real freshwater flux and observance of requisite conservation laws. We show here that these properties can be achieved in practice through use of a rescaled vertical coordinate “z*” in z-coordinate models that allows one to follow undulations in the free-surface under sea ice loading. In particular, the adoption of “z*” avoids the difficult issue of vanishing levels under thick ice.Details of the implementation within MITgcm are provided. A high resolution global ocean sea ice simulation illustrates the robustness of the z* formulation and reveals a source of oceanic variability associated with sea ice dynamics and ice-loading effects. The use of the z* coordinate allows one to achieve perfect conservation of fresh water, heat and salt, as shown in extended integration of coupled ocean sea ice atmospheric model. 相似文献
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A coupled ice-ocean model is configured for the pan-Arctic and northern North Atlantic Ocean with a 27.5 km resolution. The model is driven by the daily atmospheric climatology averaged from the 40-year NCEP reanalysis (1958–1997). The ocean model is the Princeton Ocean Model (POM), while the sea ice model is based on a full thermodynamical and dynamical model with plastic-viscous rheology. A sea ice model with multiple categories of thickness is utilized. A systematic model-data comparison was conducted. This model reasonably reproduces seasonal cycles of both the sea ice and the ocean. Climatological sea ice areas derived from historical data are used to validate the ice model performance. The simulated sea ice cover reaches a maximum of 14 × 106 km2 in winter and a minimum of 6.7 × 106 km2 in summer. This is close to the 95-year climatology with a maximum of 13.3 × 106 km2 in winter and a minimum of 7 × 106 km2 in summer. The simulated general circulation in the Arctic Ocean, the GIN (Greenland, Iceland, and Norwegian) seas, and northern North Atlantic Ocean are qualitatively consistent with historical mapping. It is found that the low winter salinity or freshwater in the Canada Basin tends to converge due to the strong anticyclonic atmospheric circulation that drives the anticyclonic ocean surface current, while low summer salinity or freshwater tends to spread inside the Arctic and exports out of the Arctic due to the relaxing wind field. It is also found that the warm, saline Atlantic Water has little seasonal variation, based on both simulation and observations. Seasonal cycles of temperature and salinity at several representative locations reveals regional features that characterize different water mass properties. 相似文献
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基于Chirp数据和Biot-Stoll模型反演南海北部陆坡海底表层沉积物物理性质 总被引：1，自引：1，他引：0
浅地层剖面是基于声学信号(频率在几百至几千赫兹)在沉积物中的传播得到可反映沉积地层结构的数据，海底反射系数与沉积物物理性质密切相关。Biot-Stoll声波传播理论模型可以预测海底沉积物的物理性质，构建反射系数等声学参数与物理参数之间的关系，但在不同的海域采用不同的参数所获得的效果不同。为此，本文基于南海北部陆坡海底表层沉积物的实测物理参数，利用Biot-Stoll模型建立研究区海底反射系数和沉积物物理性质之间的关系，结果表明模型计算值与样品实测值吻合度总体较好，偏差在0.1%～4.9%之间，并建立了频率3.5 kHz时海底反射系数与沉积物孔隙度、密度、平均粒径之间的关系方程，且方程拟合度较高，可决系数R2均大于0.99。在对典型Chirp剖面数据计算其海底反射系数的基础上，反演了海底表层沉积物的孔隙度、密度、颗粒平均粒径等物理性质，其中反演孔隙度、密度、平均粒径与实测孔隙度、密度、平均粒径相对误差均小于5%，结果与实测值基本相符，表明该反演方法在南海北部陆坡区的应用是可行的。 相似文献
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ABSTRACTIn this study, settling tests were conducted to investigate the sedimentation and self-weight consolidation behavior of seafloor sediments from Isahaya Bay, Ariake Sea, Japan. During the tests, the density variations with depth and time were measured by a gamma-ray transmission radioisotope densitometer. The test results show that the settling process of the seafloor sediments can be classified into the flocculation stage, settling stage, and consolidation stage. The settling rate of the seafloor sediments in the settling stage is dependent on the temperature and initial water content, while the settling rate in the consolidation stage is independent of the temperature and initial water content. The density profile changes from a constant density profile to a linear density profile when the sedimentation process transitions to the self-weight consolidation process. The relations between the void ratio (e) and effective vertical stress (p’) at very low pressures can be calculated from the measured density values, and this can be used for the analysis of the self-weight consolidation of seafloor sediments. For the seafloor sediments tested in this study, the undrained shear strength (su) values are almost the same when the density values are less than 1.14?g/cm3, and the su values increase linearly with an increase in density when the density values are in the range of 1.14–1.2?g/cm3. 相似文献
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Chlorophyll biomass off Sanriku, northwestern Pacific, estimated by Ocean Color and Temperature Scanner (OCTS) and a vertical distribution model 总被引：2，自引：0，他引：2
To estimate chlorophyll biomass from satellite-derived data, we established an empirical model for the estimation of the chlorophyll
vertical profile as a function of surface chlorophyll for four separate regions of the Sanriku area, using algorithms based
upon ship observations from 1986 to 1995. The modeled profiles compared well with observations during the Sanriku Field Campaign.
Chlorophyll biomass in the Sanriku Area estimated by a combination of OCTS data and the model varied from 2.6×104 t in the Oyashio water to 8.2×103 t in the Kuroshio water. 相似文献
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A simple relationship has been developed between the wall coordinate y+ and Kolmogorov's length scale using direct numerical simulation (DNS) data for a steady boundary layer. This relationship is then utilized to modify two popular versions of low Reynolds number k–ε model. The modified models are used to analyse a transitional oscillatory boundary layer. A detailed comparison has been made by virtue of velocity profile, turbulent kinetic energy, Reynolds stress and wall shear stress with the available DNS data. It is observed that the low Reynolds number models used in the present study can predict the boundary layer properties in an excellent manner. 相似文献
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AbstractThe mechanical characteristics of calcareous silt interlayers play an important role in the stability of island-reef foundations. Direct shear and consolidation tests were performed to study the relationship between the mechanical properties and the physical parameters of calcareous silt. Based on the consolidation test results and analysis of the settling examples, different calculation methods for soil settling were compared. The results show the following. (1) The relationship between the cohesion and water content of calcareous silt can be represented by an M-shaped curve. The water contents corresponding to the two peaks of the M-type curve increase with increasing dry density. (2) When the dry density is less than 1.33?g/cm3, increasing the density significantly improves the internal friction angle of calcareous silts. When the dry density of the calcareous silt is greater than 1.33?g/cm3, the internal friction angle is affected by both the dry density and the water content. (3) The shear strength decreases when the water content exceeds the optimum level. (4) The compressive modulus of calcareous silt is larger than that of terrigenous silt. Specifically, it decreases with decreasing dry density and increasing water content. (5) The stepwise loading method should be used to estimate the soil settling before fill engineering construction. 相似文献