用数字云图确定热带气旋强度的原理和方法   总被引：5，自引：1，他引：5  

范蕙君  李修芳  燕芳杰  胡治波 《大气科学》1996,20(4):439-444

本文采用数字云图资料，分析热带气旋强度与热带气旋中云系结构的关系，提出了云系结构紧密度因子的概念并用云带旋转的圈数表示热带气旋强度的方法。本文对原有关于热带气旋中云系结构的某些因子的取值作了适当调整， 改进了用增强红外云图确定热带气旋强度的方法。 经过对2446组样本的拟合，热带气旋强度最大风速估计值的平均绝对误差为2.48 m/s。本方法可以实现人机交互，能更客观地作出定量估计。对1993年12个热带气旋检验，最大风速平均绝对误差为2.31 m/s。  相似文献   

Nonlinear estimation of spatial distribution of rainfall — An indicator cokriging approach     

D-J Seo 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(2):127-150

Indicator cokriging (Journel 1983) is examined as a tool for real-time estimation of rainfall from rain gage measurements. The approach proposed in this work obviates real-time estimation of real-time statistics of rainfall by using ensemble or climatological statistics exclusively, and reduces computational requirements attendant to indicator cokriging by employing only a few auxiliary cutoffs in estimation of conditional probabilities. Due to unavailability of suitable rain gage measurements, hourly radar rain fall data were used for both indicator covariance estimation and a comparative evaluation. Preliminary results suggest that the indicator cokriging approach is clearly superior to its ordinary kriging counterpart, whereas the indicator kriging approach is not. The improvement is most significant in estimation of light rainfall, but drops off significantly for heavy rainfall. The lack of predictability in spatial estimation of heavy rainfall is borne out in the integral scale of indicator correlation: peaking to its maximum for cutoffs near the median, indicator correlation scale becomes increasingly smaller for larger cutoffs of rainfall depth. A derived-distribution analysis, based on the assumption that radar rainfall is a linear sum of ground-truth and a random error, suggests that, at low cutoffs, indicator correlation scale of ground-truth can significantly differ from that of radar rainfall, and points toward inclusion of rainfall intermittency, for example, within the framework proposed in this work.  相似文献   

不同伸展构造的形成深度和水平伸展量的估算     

陈跃辉 《华东地质学院学报》1996,19(4):315-320

本文根据断陷盆地规模，盆内盖层厚度，地层产状等要素以及控盆地断裂的几何学和运动学特征，推导了不同类型伸展构造的形成深度和水平伸展计算模式，并以信江裂陷伸展构造，衡山，南雄，会昌热隆伸展构造和新一资重力伸展构造作为实例进行计算，结果表明，三种伸展构造的形成深度明显地分三个层次，反映了不同伸展构造形成的动力学机制特征和热隆隆伸展构造较大的水平伸展，合理地解释了小型断裂盆地内形成盖层厚盖沉积的原因。  相似文献   

自适应Lp估计及其应用     

吴杰  李正心 《测绘学报》1996,25(1):31-36

本文详细介绍了自适应Ｌｐ估计的原理，计算方法和参数估值的性质，并给出了一个ＳＬＲ数据预处理的应用实例。  相似文献   

自动建立多边形拓扑关系算法步骤的优化与改进   总被引：16，自引：4，他引：16  

齐华 《测绘学报》1997,26(3):254-260

作者从算法和过程的效率、自动化水平和数据的完整性入手，简要分析了传统算法中存在的问题。在此基础上，以提高自动化水平为目的，将地理实体多边形拓扑关系的建立过程归结为：弧结点的匹配和弧连接关系的建立；同一结点上弧－弧拓扑关系的建立；闭合边界弧段相邻关系的建立；闭合边界包含关于的确定等主要步骤。给出了各主要步骤的算法，并对提高算法效率也提出了新的改进方案。分析与试验表明：新算法对于减少人工操作次数提高自  相似文献   

主成分估计与附加条件的参数平差     

宋力杰 《测绘工程》1997,6(1):24-27

证明了主成分估计实质上是附着条件的参数平差，并根据此性质结合算例分析了主成分估计的局限性，提出了改进方法。  相似文献   

伪权现象及抗差估计   总被引：1，自引：0，他引：1  

靳奉祥  王同孝 《测绘工程》1997,6(4):16-20

讨论了权与平差结果的关系，指出了残差向量与权之间不一定存在的一一对应的关系，对现行常用抗差估计方案用实例进行了研究，并建议抗差方案设计应对权函数的取值加以限制，以保证平差系统的稳健性。  相似文献   

Robust estimation and optimal selection of polynomial parameters for the interpolation of GPS geoid heights     

D. Zhong 《Journal of Geodesy》1997,71(9):552-561

The polynomial interpolation of least squares and interpolation moving least squares based on control stations with known GPS (global positioning system) ellipsoidal heights and levelling orthometric heights are the most often used methods for the interpolation of the geoid heights. But in their applications there occur two problems: one lies in selecting the suitable polynomial parameters; the other in reducing the influences of some possibly abnormal data points. To solve both of the problems, without emphasizing a sound theoretical basis, a heuristic solution with the help of robust estimation technique and optimization criteria for the regression equation is presented. Through two actual numerical examples it is shown that the new solution concept is efficient and can be realized easily on computers. Received: 23 May 1996 / Accepted: 27 March 1997  相似文献   

石油资源的定量评价预测          下载免费PDF全文

刘承祚  陶起  柴俊杰  吴泰然  英定文 《地质科学》1988,(2):170-177

本文涉及石油资源的定量评价预测。文中介绍了六种方法:随机过程法、搜索区分析法、油田规模分布的极大似然估计法、蒙特卡洛法、经验分布变换法、模糊综合评判法。这些方法在我国中部一个油田石油资源评价预测中得到应用并获得了满意的结果。  相似文献   

Spatial rainfall estimation by linear and non-linear co-kriging of radar-rainfall and raingage data     

A. Azimi-Zonooz  W. F. Krajewski  D. S. Bowles  D. J. Seo 《Stochastic Hydrology and Hydraulics》1989,3(1):51-67

The feasibility of linear and nonlinear geostatistical estimation techniques for optimal merging of rainfall data from raingage and radar observations is investigated in this study by use of controlled numerical experiments. Synthetic radar and raingage data are generated with their hypothetical error structures that explicitly account for sampling characteristics of the two sensors. Numerically simulated rainfall fields considered to be ground-truth fields on 4×4 km grids are used in the generation of radar and raingage observations. Ground-truth rainfall fields consist of generated rainfall fields with various climatic characteristics that preserve the space-time covariance function of rainfall events in extratropical cyclonic storms. Optimal mean areal precipitation estimates are obtained based on the minimum variance, unbiased property of kriging techniques under the second order homogeneity assumption of rainfall fields. The evaluation of estimated rainfall fields is done based on the refinement of spatial predictability over what would be provided from each sensor individually. Attention is mainly given to removal of measurement error and bias that are synthetically introduced to radar measurements. The influence of raingage network density on estimated rainfall fields is also examined.  相似文献