共查询到20条相似文献，搜索用时 187 毫秒
1.
Reconstruction of the surface temperature fields according to the fragmentary data of remote sensing
E. F. Vasechkina 《Physical Oceanography》2011,21(3):195-210
We propose a gap-filling method for the data of remote sensing of the hydrophysical and biological characteristics of the
water surface. The proposed method of reconstruction is based on the representation of the fields of surface characteristics
as the sums of certain numbers of empirical orthogonal functions (EOF) making the largest contributions to the total variance
of the field. According to the fragmentary data obtained as a result of processing of the satellite images for the summer
season, we construct estimates of the mean field and of the four-dimensional space covariance function of the surface temperature
of the Black Sea. The coefficients of expansion are computed by the method of least squares or determined with the help of
a genetic searching algorithm. The results of numerical experiments show that the proposed method is quite promising for applications
in the problems of gap filling in the available satellite data. 相似文献
2.
Reconstruction of incomplete oceanographic data sets using empirical orthogonal functions: application to the Adriatic Sea surface temperature 总被引：8，自引：1，他引：8
A method for the reconstruction of missing data based on an EOF decomposition has been applied to a large data set, a test case of Sea Surface Temperature satellite images of the Adriatic Sea. The EOF decomposition is realised with a Lanczos method, which allows optimising computational time for large matrices. The results show that the reconstruction method leads to accurate reconstructions as well as a low cpu time when dealing with realistic cases. The method has been tested with different amounts of missing data, artificially adding clouds ranging from 40% to 80% of data loss, and then compared to the same data set with no missing data. A comparison with in situ data has also been made. These validation studies show that results are robust, even when the amount of missing data is very high. The reconstruction of the data from the Adriatic Sea shows realistic features and a reliable temperature distribution. In addition, the method is compared to an Optimal Interpolation reconstruction. The results obtained with both methods are very similar. The main difference is the computational time, which is reduced nearly 30 times with the method presented here. Once the reconstruction has been performed, the EOF decomposition is analysed to show the method’s reliability, and a cold event on the Albanian coast is studied. The reconstructed data reflect the effect of wind on the Albanian coast, that led to a cold-water episode in this zone for a 6-day period. 相似文献
3.
A. P. Tolstosheev 《Physical Oceanography》2009,19(6):358-365
A method for the estimation of the results of reconstruction of the trajectories of drifting buoys is proposed. It is based
on the comparison of the estimates of power spectral densities for the components of current velocity computed according to
three data sets: the data set of the coordinates of a drifting buoy with a built-in GPS receiver, the data set of coordinates formed on the basis of the first set but with data missing and observational errors
corresponding to the actual trajectory measurements by the Argos satellite location and data collection system by the Doppler method, and the data set of coordinates obtained as a result
of interpolation of the second set. As an example, we consider the procedure of realization of the proposed method and demonstrate
the efficiency of its application for the improvement of the reliability of reconstruction of the trajectories of drifting
buoys. 相似文献
4.
静止轨道海洋水色成像仪(Geostationary Ocean Color Imager, GOCI)提供了时间分辨率达小时级的海洋水色数据,使得对海洋环境的逐时变化监测成为可能。然而受到海洋上空云、雾和霾的影响,数据出现连续高缺失率甚至完全缺失的情况,使得数据使用价值大大降低。在经验正交函数重构法(Data INterpolating Empirical Orthogonal Functions, DINEOF)的基础上,突出时间要素在重构中的地位,运用异常像元检测、拉普拉斯平滑滤波和时间模态2次分解插值,提出了适用于静止海洋水色卫星数据的重构方法——DINEOF-G。利用此方法对杭州湾2017年的GOCI总悬浮物质量浓度数据进行重构,结果表明该方法相比经典方法在重构精度上提高了8%,数据重构率提高了36%,且重构结果较好地反映了杭州湾总悬浮物质量浓度的季节变化规律和空间分布特征。 相似文献
5.
A method for reconstructing the parameters of postvolcanic stratospheric aerosol from the results of joint measurements of the aerosol backscattering coefficient with lidar systems based on the Nd:YAG laser and the aerosol extinction coefficient with the SAGE III satellite instrumentation is developed. The most informative set of optical characteristics is determined for each of the microphysical parameters under consideration (concentration, surface area, volume, and effective size of particles of the fine and coarse aerosol fractions). Multiple polynomial regressions between optical and microphysical characteristics of aerosol are obtained. These regressions make it possible to determine the microphysical characteristics of aerosol within a wide range without solving incorrect inverse problems. The results are compared with independent experimental data. The errors of reconstructing microphysical parameters of aerosol are estimated for different situations in the stratosphere. The influence of the shape of particles of the dust fraction on the results of a reconstruction of the microphysical parameters of aerosol is considered. 相似文献
6.
建立1种新的射影重建方法。该方法以全局性极小化射影三维空间点的二维反投影误差平方和为准则,相对于缩小SVD反投影误差的方法,具有更为明确合理的物理意义。实现过程是以奇异值分解为基本工具的分步线性迭代计算,避免了传统射影重建方法复杂的非线性优化环节。它无需估计投影深度,避免了基础矩阵计算的复杂性问题,因而也不受相机特殊运动的限制。文中利用虚拟物体图像和真实物体图像进行了实验验证,证明该方法具有计算简单、准确性和鲁棒性高等方面的特点,具有较高的实用价值。 相似文献
7.
The paper suggests a method for reconstructing the spatial structure of hydrological elements, using incomplete information,
with the noise component being concurrently filtered. This problem is of vital relevance in the context of conducting satellite
observations when the observed area is covered by clouds. To solve the problem, the fields are decomposed by the system of
empirical orthogonal functions.
The reconstructed fields acquired by the different techniques using model andin situ data are then compared. As an example, the paper examines the reconstruction of the oxygen field, using the survey data compiled
during the summer of 1986. The computations allow a deduction that the method at issue may be efficiently employed to handle
the problems of field reconstruction, using scarce data, with the purpose of generating a data base on spatio-temporal variability
of diverse environment components.
Translated by Vladimir A. Puchkin. 相似文献
8.
在内波条件下,水声信道稳定性变差,声速剖面的重构具有一定难度。与其他方法相比,经验正交分解法优点在于能用少量参数进行重构,而不需要引入大量的参数。利用南海北部陆坡测量的温度链数据,采用经验正交分解法对声速剖面进行重构。结果表明:在内波剧烈的南海北部海域,通过经验正交分解法重构声速剖面具有可行性,其前3个模态累计贡献率达到96.7%。分析样本的周期覆盖率对重构结果的影响后发现,当样本覆盖完整的海洋潮汐活动周期时,基于EOF分析对本组声速剖面的重构均方根误差小于1.1 m/s,重构声速剖面结果理想;而当采集的样本不能覆盖完整周期时,误差较大。 相似文献
9.
针对单幅平行六面体类建筑物图像,提出1种从参数化建模角度解决城市建筑物重建的方法.结合多尺度分析,由贝叶斯概率模型对边缘像素分类自动获取建筑物轮廓,利用平行六面体几何结构与相机参数的对偶性,确定场景及建筑物目标参数.该方法可在不需要人工交互的情况下,由单幅图像完成平行六面体类建筑物结构参数的提取.通过模拟图像和自然图像的实验,结果说明本文提出的方法简单、有效. 相似文献
10.
针对混响环境非自由声场中声源测量的问题,本文以消声水池和混响水槽为实验环境,以换能器辐射的声场为研究对象,以水听器阵列为测量前端,进行了混响环境非自由声场中声源对象的测量、分析和重构的实验研究。通过单层水听器阵列对非自由声场进行声压分布测量,并对测量结果作声波分离处理,将分离前后的声压分布和在消声水池中测量的声压分布进行比较,给出了声源频率为5 000 Hz和7 000 Hz时,声场重构的误差分析结果。结果表明,基于单层水听器阵列声压测量的声波分离方法,能够较精确地对混响环境中的声场进行重构。 相似文献
11.
针对复杂的工业环境和目前工控产品的缺陷 ,本文提出 1种基于多 Agent理论的智能化现场总线数据采集系统的设计方法。结合多 Agent理论和现场总线技术 ,构建了 1种具有良好的系统重构能力、容错能力和快速反应能力的多 Agent数据采集系统。并对系统中 Agent的功能、硬件结构以及通讯方式进行了详细探讨 相似文献
12.
海洋立管是深海油气开发中用于连接海底井口和水面浮体的唯一通道。立管在洋流作用下极易发生涡激振动（vortex-induced vibration,简称VIV）,发展快速经验性涡激振动时域预报方法对立管的安全设计具有重要意义。通过柔性立管模型试验,结合载荷重构方法和最小二乘法,识别建立了能量竞争载荷模型下的经验水动力载荷系数模型。应用识别建立的经验水动力载荷系数模型,发展形成了海洋立管顺流向及横流向双向涡激振动时域预报方法。将预报结果与试验结果对比,结果表明：基于能量竞争载荷模型的海洋立管双向涡激振动预报方法能够有效预报海洋立管涡激振动主导模态、主导频率、流向平均位移响应和涡激振动位移响应等力学行为特性。研究成果对发展更为有效的涡激振动预报手段具有有益参考。 相似文献
13.
建立了求解一维全非线性Green-Naghdi水波方程的中心有限体积/有限差分混合数值格式。采用结构化网格对守恒形式的控制方程进行离散和积分,界面数值通量采用有限体积法计算,剩余项则采用中心有限差分格式求解。其中,采用中心迎风有限体积格式计算控制体界面数值通量,并结合界面变量的线性重构方法,使其在空间上具有四阶精度,通过引入静压重构技术和波浪破碎指标使模型具备处理海岸水-陆动边界及波浪破碎的能力。时间积分则采用具有总时间变差减小(Total Variation Diminishing,TVD)性质的三阶龙格-库塔法进行。应用该模型对孤立波在常水深和斜坡海岸上的传播过程及规则波跨越潜堤传播的实验进行了数值模型研究,数值计算同解析解及实验数据吻合良好。 相似文献
14.
文章利用果蝇优化广义回归神经网络算法FOAGRNN (fruit fly optimization algorithm, FOA; generalized regression neural network, GRNN)对SODA (simple ocean data assimilation)再分析数据进行训练, 构建海表温度、盐度、海面高度与次表层温盐场之间的投影关系模型, 并在全球范围使用SODA和卫星遥感数据评估了模型的应用性能。首先, 利用独立的2016年SODA海表数据作为模型输入进行理想重构试验, 结果显示全球重构温、盐平均均方根误差(MRMSE)分别为0.36℃和0.08‰, 与世界海洋图集WOA13资料相比减小约50%和60%。然后, 利用卫星观测的海表信息作为模型输入进行实际应用试验, 并与Argo观测剖面进行比较评估。试验结果表明, 重构模型能有效表征海水温、盐特征, 其中重构温、盐MRMSE分别为0.79℃和0.16‰, 相比WOA气候态减小27%和11%。误差的垂向分布显示, 重构温度RMSE从海表向下迅速增大, 至100m达到峰值1.35℃, 而后又迅速回落,至250m处为0.81℃, 跃层往下不断减小; 重构盐度RMSE基本随深度增大而减小, 误差峰值位于25m附近, 约为0.25‰。此外, Argo浮标跟踪分析和区域水团统计结果也表明模型能够较好地刻画海洋三维温盐场的内部结构特征。 相似文献
15.
As for the satellite remote sensing data obtained by the visible and infrared bands inversion, the clouds coverage in the sky over the ocean often results in missing data of inversion products on a large scale, and thin clouds di?cult to be detected would cause the data of the inversion products to be abnormal. Alvera et al.(2005) proposed a method for the reconstruction of missing data based on an Empirical Orthogonal Functions (EOF) decomposition, but his method couldn’t process these images presenting ex... 相似文献
16.
Rongxing Li 《Marine Geodesy》2013,36(2-3):115-127
Shape from shading is one of the methods that derive geometric information of objects from analysis of monocular images. Application of this technique to underwater sonar images enables the conversion of imposed reflectance characteristics in sonar images to shape information, namely, slopes, about the seafloor surface. A combination of this shape information and available sparse distributed depth points results in improved dense bathymetric data. The reconstruction of shape models of seafloor surfaces from sonar images is treated as an inverse problem and is solved by the regularization theory. Sparse gridded points are used for boundary constraints. The regularization is implemented as a relaxation procedure with a hierarchical structure of multiresolution grids. 相似文献
17.
We propose a method for the solution of the inverse problem of reconstruction of the vertical stratification of density in the ocean according to the known dispersion curves for internal gravity waves. For the stratification of density modeled by a linear distribution, we determine the accuracy of its reconstruction for values of the frequency of oscillations and wave numbers given with different degrees of accuracy. The posed problem is studied in the Boussinesq approximation for two traditionally used types of boundary conditions on the surface of the fluid. We deduce dispersion equations and focus our attention on their asymptotic analysis. An asymptotic solution of the inverse problem is constructed and its sensitivity to the degree of accuracy of the input data is investigated. 相似文献
18.
Analysis of the morphometric characteristics from a study of the Barents Sea seabed has shown that the existing troughs are consistent with geodynamic conclusions, allowing morphological typing into structural slopes and reconstruction of their origin. Thus, the Norwegian–Mezenskaya rift system and Svyataya Anna and Victoria troughs were formed due to stretching of the lithosphere. The South Barents and Medvezinsko- Edzinskaya depressions formed at the generation stage of lithospheric plates due to the collision of several island arcs between outliers of the ancient oceanic crust. The choice of the geomorphic method for studying the seabed is because the science of geomorphology comprehensively studies bottom relief (morphology), its origin, and age. Adequate reconstruction of the causal relationships of exogenous and endogenous processes aids in substantiating the prediction of probable catastrophic seabed events. The results of mathematical calculations have confirmed the geodynamic conclusions within the Barents Sea region. 相似文献
19.
In this paper an interaction method is proposed for estimating the buoyancy frequency as a function of depth based on the frequency dependence of wave numbers of internal normal waves. Examples are given of the numerical reconstruction of buoyancy frequency profiles demonstrating convergence of the algorithm. An iterative scheme for the solution of the given problem with an expanded convergence area is obtained on the basis of iteration by stages.Translated by M M. Trufanov. 相似文献
20.
东海、黄海近代沉积物中生物硅含量的分布及其反演潜力 总被引：11，自引：8，他引：3
以东海、黄海2006年4月、10月航次采集的沉积物样品为研究对象,结合沉积物中生物硅(BSi)含量的空间分布特征进而讨论BSi的反演潜力。研究发现,调查海域表层沉积物中BSi的含量介于0.018%~2.516%,平均值为0.726%,柱状沉积物中BSi的含量波动较小,相对稳定。整体而言BSi含量与相应年代的浮游植物现存量变化的趋势相近。经一元线性分析发现BSi含量与硅藻生物量的相关性显著。为进一步证实由BSi含量反演古生产力的有效性和可信度,采用Tun-nicliffe等的方法探讨了BSi含量在沉积物中的稳定性,调查结果表明,近150 a来BSi几乎没有降解,能够稳定地保存于沉积物中。综上可以初步判断沉积物中BSi含量可作为古生产力指标来反演古生产力的潜力。 相似文献