Teacher''s Aide: Geologic Characteristics of Hole-Effect Variograms Calculated from Lithology-Indicator Variables     

Thomas A. Jones  Yuan Z. Ma 《Mathematical Geology》2001,33(5):615-629

Variograms calculated from binary variables, such as from two lithologies, tend to show sinusoidal forms with decreasing amplitudes for increasing lag distances. This cyclicity is observed often when analyzing drill-hole data for rock sequences with alternating lithologies, and the variograms are thus labeled hole-effect variograms. Such variograms show a variety of forms: (1) Low to moderate variation in lithologic-body dimensions causes variograms to have strong cyclicity with decaying amplitude. (2) Variograms with one or more peaks and troughs usually result from a binary variable for which lithologies are about equally abundant but possibly large variations exist in the size of lithologic bodies. (3) Variograms show poor cyclicity if one lithology has highly variable body sizes and the other has moderately variable body dimensions. (4) Variograms that attain a plateau at short lag distances represent extremely high or low sandstone fraction, high variability in size of the most abundant lithology, and low variability in the other. Information about the dimensions of lithologic bodies makes it possible to approximate characteristics of the variogram of the lithology variable without numerous wells. Conversely, a hole-effect variogram of lithology may be used to estimate lithologic dimensions.  相似文献   

Spatio-temporal regression kriging for modelling urban NO2 concentrations     

Vera van Zoest  Frank B. Osei  Gerard Hoek  Alfred Stein 《International journal of geographical information science》2020,34(5):851-865

ABSTRACT

Recently developed urban air quality sensor networks are used to monitor air pollutant concentrations at a fine spatial and temporal resolution. The measurements are however limited to point support. To obtain areal coverage in space and time, interpolation is required. A spatio-temporal regression kriging approach was applied to predict nitrogen dioxide (NO₂) concentrations at unobserved space-time locations in the city of Eindhoven, the Netherlands. Prediction maps were created at 25 m spatial resolution and hourly temporal resolution. In regression kriging, the trend is separately modelled from autocorrelation in the residuals. The trend part of the model, consisting of a set of spatial and temporal covariates, was able to explain 49.2% of the spatio-temporal variability in NO₂ concentrations in Eindhoven in November 2016. Spatio-temporal autocorrelation in the residuals was modelled by fitting a sum-metric spatio-temporal variogram model, adding smoothness to the prediction maps. The accuracy of the predictions was assessed using leave-one-out cross-validation, resulting in a Root Mean Square Error of 9.91 μg m^?3, a Mean Error of ?0.03 μg m^?3 and a Mean Absolute Error of 7.29 μg m^?3. The method allows for easy prediction and visualization of air pollutant concentrations and can be extended to a near real-time procedure.  相似文献   

Geostatistics for assessing the efficiency of a distributed physically‐based water quality model: application to nitrate in the Seine River     

Edwige Polus  Nicolas Flipo  Chantal de Fouquet  Michel Poulin 《水文研究》2011,25(2):217-233

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支持向量机优化的克里金插值算法及其海洋资料对比试验     

王辉赞  张韧  刘巍  刘科峰  王桂华 《南京气象学院学报》2011,34(5):567-573

针对常规克里金插值方法中变异函数为有限确定函数,难以准确刻画实际数据分布（特别是复杂要素资料的空间结构）的不足,基于最小二乘支持向量机从实际资料场中拟合重构变异函数的研究思想,提出了一种改进的插值方法——支持向量机—克里金插值算法（SVM-Kriging）。采用常规的克里金方法和支持向量机—克里金插值方法（SVM-Kriging）进行插值试验和对比分析,结果表明：支持向量机—克里金方法（SVM-Kriging）的变异函数源自实际的数据场,它克服了常规克里金插值对变异函数选择的依赖性以及变异函数选择的主观性和人为性,表现出较好的针对性和客观性,较为有效地改善了插值效果。  相似文献   

协同克里格方法在东海表面温度场数据插值中的应用     

宋庆磊  杜德文  丁明  闫仕娟 《海岸工程》2011,30(3):49-55

首次将协同克里格方法引入到海洋水文插值计算中处理东海实验区2008-01—2008-03三个月抽稀后的月平均海表面温场数据。将温场数据分为趋势分量和剩余分量,最终采用两分量的估计值之和实现海表面温场数据的格网插值估计。结果表明：协同克里格方法比传统方法（趋势分析、移动平均、普通克里格插值）效果好。提出变差函数局部拟合的...  相似文献   

长三角工业化转型的空间分异研究   总被引：1，自引：0，他引：1  

赵孟孟  董平  陆玉麒 《热带地理》2011,31(1):58-64

通过构建工业化转型发展的评价体系,借助于地统计学的空间自相关和空间变异函数,对长三角135个县域单元工业化转型发展水平的空间格局进行研究,结果表明:"扩容"后的长三角工业化发展水平整体上呈现以上海为龙头,沿沪宁、沪杭两个方向扩展,在苏中北和浙西南地带以区域中心城市为增长极向外扩散的特征;中心城市在工业化过程中的空间极化...  相似文献   

新疆县域经济空间格局演化特征   总被引：8，自引：1，他引：7  

王静  张小雷  杜宏茹 《地理科学进展》2011,30(4):470-478

通过ESDA空间分析,研究1985年以来新疆县域经济格局在空间上的变化及其特征.结果表明:1985年以来新疆县域经济发展水平表现出较弱的空间自相关性,但集聚作用总体不断增强.热点区的空间结构主要集中在以奎-克-乌为核心的圈形结构,2000年以后热点区显著增加,不断向北疆中部、东疆以及南疆东北部集聚;南疆西南部处于经济发...  相似文献   

Variogram models for regional groundwater geochemical data     

D. E. Myers  C. L. Begovich  T. R. Butz  V. E. Kane 《Mathematical Geology》1982,14(6):629-644

Four variogram models for regional groundwater geochemical data are presented. These models were developed from an empirical study of the sample variograms for more than 10 elements in groundwaters from two geologic regions in the Plainview quandrangle, Texas. A procedure is given for the estimation of the variogram in the isotropic and anisotropic case. The variograms were found useful for quantifying the differences in spatial variability for elements within a geologic unit and for elements in different geologic units. Additionally, the variogram analysis enables assessment of the assumption of statistical independence of regional samples which is commonly used in many statistical procedures. The estimated variograms are used in computation of kriged estimates for the Plainview quadrangle data. The results indicate that an inverse distance weighting model was superior for prediction than simple kriging with the particular variograms used.  相似文献   

Statistical and geostatistical methods applied to the exploration work of the Nanisivik Zn-Pb mine, Baffin Island, Canada     

F. -W. Wellmer  G. H. Giroux 《Mathematical Geology》1980,12(4):321-337

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基于Kriging方法的空间数据插值研究   总被引：11，自引：0，他引：11  

曾怀恩  黄声享 《测绘工程》2007,16(5):5-8

介绍了Kriging插值方法及其实质,提出一种变异函数理论模型参数估计的新方法,给出变异函数理论模型有效性评定的统计指标,并通过算例予以验证。最后,通过实例与反距离加权法相比较,证实Kriging插值的优越性。  相似文献