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Land data assimilation (DA) has gradually developed into an important earth science research method because of its ability to combine model simulations and observations. Integrating new observations into a land surface model by the DA method can correct the predicted trajectory of the model and thus, improve the accuracy of state variables. It can also reduce uncertainties in the model by estimating some model parameters simultaneously. Among the various DA methods, the particle filter is free from the constraints of linear models and Gaussian error distributions, and can be applicable to any nonlinear and non-Gaussian state-space model; therefore, its importance in land data assimilation research has increased. In this study, a DA scheme was developed based on the residual resampling particle filter. Microwave brightness temperatures were assimilated into the macro-scale semi-distributed variance infiltration capacity model to estimate the surface soil moisture and three hydraulic parameters simultaneously. Finally, to verify the scheme, a series of comparative experiments was performed with experimental data obtained during the Soil Moisture Experiment of 2004 in Arizona. The results show that the scheme can improve the accuracy of soil moisture estimations significantly. In addition, the three hydraulic parameters were also well estimated, demonstrating the effectiveness of the DA scheme. 相似文献
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多源、多尺度遥感影像为研究不同尺度的地表变化提供了丰富的数据。但其在作比较研究时,通常会涉及空间尺度统一问题,当多源遥感影像之间的空间分辨率为非整倍数关系时,其空间尺度统一相对困难。为此,本文针对多源、多尺度遥感影像间尺度比较时所涉及的空间尺度转换问题,提出了最大公约数的空间尺度转换算法,并以IKONOS多光谱影像为数据源,采用若干商业软件和本文所提算法进行空间尺度转换比较实验;同时,利用均值、标准差和相关系数等6个评价指标对空间尺度变换后的影像进行定量评价。结果表明,本文提出的空间尺度转换方法对原始影像的光谱信息等特征具有很好的保真性,简单易行,可实现遥感影像任意空间尺度的转换,解决了多源遥感影像之间的空间分辨率为非整倍数关系时的空间尺度转换问题。 相似文献
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Unlike parametric alternatives for time series generation, non-parametric approaches generate new values by conditionally resampling past observations using a probability rationale. Observations lying ‘close’ to the conditioning vector are resampled with higher probability, ‘closeness’ is defined using a Euclidean or Mahalanobis distance formulation. A common problem with these approaches is the difficulty in distinguishing the importance of each predictor in the estimation of the distance. As a consequence, the conditional probability and hence the resampled series, can offer a biased representation of the true population it aims to simulate. This paper presents a variation of the K-nearest neighbour resampler designed for use with multiple predictor variables. In the modification proposed, an influence weight is assigned to each predictor in the conditioning set with the aim of identifying nearest neighbours that represent the conditional dependence in an improved manner. The workability of the proposed modification is tested using synthetic data from known linear and non-linear models and its applicability is illustrated through an example where daily rainfall is downscaled over 15 stations near Sydney, Australia using a predictor set consisting of selected large-scale atmospheric circulation variables. 相似文献
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以研究区1∶10 000DEM和DLG数据为基础,分别提出基于DLG数据和DEM数据的精细化处理方法,并对比分析了最近邻域法、双线性内插法以及三次卷积法三种重采样方法对DEM精细化处理效果的影响,结果表明:双线性内插法在时间效率、数据精度以及图像效果方面均适中,故决定采用双线性内插法将研究区5m格网DEM数据通过重采样生成为2m格网DEM数据,最后通过可视化和检查点法验证了精细化处理的精度均满足相关要求。相关研究成果可为地形特征等数据的提取提供精度较高的基础数据。 相似文献
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对多卫星传感器数据进行融合,首先要将多个传感器数据通过重采样算法重新投影到标准网格上。本文运用一种基于多边形切割算法的通量守恒重采样算法对图像数据进行重采样,并将该算法与3种常用的重采样算法(最邻近插值法、双线性插值法、三次卷积插值法)在信息保真方面的性能进行了比较。将所比较的重采样方法应用于两幅具有代表性的图像,其中一幅为人造图像,用于定性比较各种采样方法在图像缩放中的采样精度;另一幅为某机场卫星遥感图像,用于评价各种重采样方法在旋转图像方面采样的性能,并以定量参数(相关系数及光谱真实性)比较各种采样方法。结果表明,通量守恒重采样法对原始图像的信息保真效果最好,更适用于卫星遥感图像数据融合中的重采样。 相似文献
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Abstract Four geoelectrical soundings were measured with a combination of Schlumberger and azimuthal or equatorial dipole electrode arrays on a Carboniferous limestone basin of the Condroz area, Belgium. The measuring technique is briefly outlined as well as the interpretation procedure, which follows a closed-loop scheme with control of calculated model curves. Some general problems of interpretation of geoelectrical sounding curves are tackled, as far as they have a practical bearing on the treatment of Condroz soundings. The problem of determining the very high resistivity of limestone is approached through ARCHIE's formula, an empirical relation between the bulk rock resistivity, the porosity and the electrolyte resistivity. An evaluation of the latter two parameters, combined with electrical horizontal conductance measurements directly made on resistivity sounding curves, offers a possibility for fast determination of the total water storage in a limestone aquifer. Such storage determinations could be applied whenever an aquifer shows up as a conductive layer interbedded between two highly resistant layers (e.g. nonsaturated limestone and compact, non-fractured limestone). 相似文献
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韩玲 《地球科学与环境学报》1997,(4)
结合实例，讨论了在象素坐标变换中，如何建立纠正变换函数式，即建立影象坐标与地面（或地图）坐标间的数学关系式。 相似文献
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发展了一种根据单台垂向记录的地震直达P波的第一个周期信号, 研究地震波传播路径中介质衰减频散特性的方法. 为了更有效地提高P波频散测量的分辨率和信噪比水平,减小系统误差,使用了数据重采样技术. 应用改进的多重滤波方法测定P波群速度延迟. 根据线性滞弹性体松弛模型反演得到了介质品质因子Qm、95%置信水平下的测量误差及相关参数. 对营口台记录的辽宁岫岩震群的研究结果表明:① 1999年11月9日开始出现高Qm值,高Qm值对应的地震集中在距营口台32~46 km, 明显偏离Qm随震中距增加的线性规律;②5.4级地震前平均Qm值为460, 5.4级地震后至2000年1月12日5.1级地震之前Qm值为391, 5.1级地震之后Qm值为204. 相似文献
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