Statistical diagnosis and gross error test for semiparametric linear model     

Shijun Ding  Songlin Zhang  Weiping Jiang  Shouchun Wang 《地球空间信息科学学报》2013,16(4):296-302

This paper systematically studies the statistical diagnosis and hypothesis testing for the semiparametric linear regression model according to the theories and methods of the statistical diagnosis and hypothesis testing for parametric regression model. Several diagnostic measures and the methods for gross error testing are derived. Especially, the global and local influence analysis of the gross error on the parameter X and the nonparameter s are discussed in detail; at the same time, the paper proves that the data point deletion model is equivalent to the mean shift model for the semiparametric regression model. Finally, with one simulative computing example, some helpful conclusions are drawn.  相似文献   

Optimization of land use structure based on ecological GREEN equivalent     

Liu Yanfang  Ming Dongping  Yang Jianyu 《地球空间信息科学学报》2013,16(4):60-67

Optimization of land use structure consists of economic and social and ecological optimization. Applying the minds of system engineering and principles of ecology, this paper presents such thoughts: the optimal forest-coverage rate calculated according to the reality of a district is set as main standard of ecological rationality in the district; through considering the value of ecosystem services of the land with GREEN equivalent (mainly cultivated land and grassland) and based on the rule, GREEN equivalent, this paper introduces the area conversion between woodland and cultivated land, also between woodland and grassland; this paper establishes a multi-dimension controlling model of optimization of land use structure. In addition, a multi-objective linear programming model for optimization of land use structure is designed. In the end, this paper tests and verifies this theory of ecological optimization, taking Qionghai city in Hainan Province as an example.  相似文献   

A Comprehensive Observational Analysis for the Effects of Gas Cannons on Clouds and Precipitation     

吴彬  王丹丹  李艳芳  尹浩  杜爽  黎朋红 《热带气象学报(英文版)》2022,28(2):237-251

To analyze the effects of gas cannons on clouds and precipitation, multisource observational data, including those from National Centers for Environmental Prediction (NCEP) reanalysis, Hangzhou and Huzhou new-generation weather radars, laser disdrometer, ground-based automatic weather station, wind profiler radar, and Lin''an C-band dual polarization radar, were adopted in this study. Based on the variational dual-Doppler wind retrieval method and the polarimetric variables obtained by the dual-polarization radar, we analyzed the microphysical processes and the variations in the macro - and microphysical quantities in clouds from the perspective of the synoptic background before precipitation enhancement, the polarization echo characteristics before, during and after enhancement, and the evolution of the fine three-dimensional kinematic structure and the microphysical structure. The results show that the precipitation enhancement operation promoted the development of radar echoes and prolonged their duration, and both the horizontal and vertical wind speeds increased. The dual-polarization radar echo showed that the diameter of the precipitation particles increased, and the concentration of raindrops increased after precipitation enhancement. The raindrops were lifted to a height corresponding to 0 to -20 ℃ due to vertical updrafts. Based on the disdrometer data during precipitation enhancement, the concentration of small raindrops (lgNw) showed a significant increase, and the mass-weighted diameter Dm value decreased, indicating that the precipitation enhancement operation played a certain“lubricating”effect. After the precipitation enhancement, the concentration of raindrops did not change much compared with that during the enhancement process, while the Dm increased, corresponding to an increase in rain intensity. The results suggest the positive effect of gas cannons on precipitation enhancement.  相似文献   

基于多源数据的湘北地区春季一次冰雹过程的观测分析          下载免费PDF全文

朱家亮  潘江萍  邱丽静  吕渊 《中低纬山地气象》2022,46(2):46-54

新型探测资料在强对流短临预报中发挥着重要作用.该文以2020年3月22日湘北地区春季一次冰雹过程为研究对象,运用多普勒天气雷达、风廓线雷达和地基微波辐射计等新型探测资料对该过程观测分析。结果表明：①此次过程发生在冷空气南下与南支槽前暖湿空气交汇背景下,受中低层切变线与急流影响,冰雹风暴生成前回暖明显,环境垂直风切变大;风暴由地面辐合线触发产生。②此次超级单体降雹过程在雷达回波中表现出“三体散射”、“V型缺口”、中气旋等特征;VIL、低仰角大风速核对冰雹、大风预警有很好的指示。③风廓线雷达探测到,风暴影响前超低空急流加强,中层有干侵入,低层垂直速度出现波动,风暴临近时超低空急流减弱。④地基微波辐射计监测发现,风暴影响前高空湿度增大,K指数、TT指数呈同趋势变化,而K指数预警灵敏度高于TT指数;风暴影响阶段,高空温度、相对湿度和大气不稳定指数出现不同程度跃升和突降。  相似文献   

深圳S波段与X波段双偏振雷达在定量降水估计中的应用   总被引：3，自引：0，他引：3  

张哲  戚友存  朱自伟  李东欢  曾庆锋  兰红平 《气象学报》2021,79(5):786-803

双偏振多普勒天气雷达的一个重要应用是进行定量降水估计（QPE）,它可以获得反射率（Z_H）、差分反射率（Z_DR）和差传播相移率（K_dp）这些与降水粒子有关的信息,常用的双偏振雷达降水估计方法有基于Z_H的R（Z_H）、基于Z_H和Z_DR的R（Z_H,Z_DR）、基于K_dp的R（K_dp）和基于K_dp与Z_DR的R（K_dp,Z_DR）这4种。文中利用深圳市S波段和X波段双偏振多普勒雷达探测资料,结合高精度地形数据和雨滴谱仪观测数据,设计了基于双偏振量的定量降水估计方法:首先利用地形数据和雷达地理信息,分析了雷达的遮挡状况,形成了这两部雷达的复合平面扫描仰角信息;随后利用雨滴谱仪观测资料,使用T矩阵方法统计得到了深圳地区的上述4种降水反演方法的参数;最后设计了混合降水反演方法,基于双偏振信号（即K_dp和Z_DR）的强弱,使用不同的降水反演方法进行定量降水估计。基于12个降水个例,利用各反演方法产生的定量降水估计结果与雨量计观测资料比较。结果表明,混合降水反演方法在降水反演的准确度和稳定性上均优于任何一种单一定量降水估计反演方法。基于文中介绍的定量降水估计方法,使用深圳S波段和X波段雷达产生了定量降水估计产品,并与深圳目前业务定量降水估计产品进行对比评估。结果表明,使用本方法产生的定量降水估计产品在准确度和稳定性上要优于目前的业务产品。此外,X波段雷达的定量降水估计产品性能要略高于S波段雷达的定量降水估计产品,这说明高时、空分辨率的X波段雷达可以提高定量降水估计精度。但由于雷达扫描平面内双偏振雷达对融化层和冰区的偏振量观测与降水的关系尚未明确,因此,本方法仅适用于雷达扫描平面内液态降水区。   相似文献   

Identification of Convective and Stratiform Clouds Based on the Improved DBSCAN Clustering Algorithm     

Yuanyuan ZUO  Zhiqun HU  Shujie YUAN  Jiafeng ZHENG  Xiaoyan YIN  Boyong LI 《大气科学进展》2022,39(12):2203-2212

A convective and stratiform cloud classification method for weather radar is proposed based on the density-based spatial clustering of applications with noise (DBSCAN) algorithm. To identify convective and stratiform clouds in different developmental phases, two-dimensional (2D) and three-dimensional (3D) models are proposed by applying reflectivity factors at 0.5° and at 0.5°, 1.5°, and 2.4° elevation angles, respectively. According to the thresholds of the algorithm, which include echo intensity, the echo top height of 35 dBZ (ET), density threshold, and ε neighborhood, cloud clusters can be marked into four types: deep-convective cloud (DCC), shallow-convective cloud (SCC), hybrid convective-stratiform cloud (HCS), and stratiform cloud (SFC) types. Each cloud cluster type is further identified as a core area and boundary area, which can provide more abundant cloud structure information. The algorithm is verified using the volume scan data observed with new-generation S-band weather radars in Nanjing, Xuzhou, and Qingdao. The results show that cloud clusters can be intuitively identified as core and boundary points, which change in area continuously during the process of convective evolution, by the improved DBSCAN algorithm. Therefore, the occurrence and disappearance of convective weather can be estimated in advance by observing the changes of the classification. Because density thresholds are different and multiple elevations are utilized in the 3D model, the identified echo types and areas are dissimilar between the 2D and 3D models. The 3D model identifies larger convective and stratiform clouds than the 2D model. However, the developing convective clouds of small areas at lower heights cannot be identified with the 3D model because they are covered by thick stratiform clouds. In addition, the 3D model can avoid the influence of the melting layer and better suggest convective clouds in the developmental stage.  相似文献   

基于GIS的线性构造异常和裂缝综合分析     

王京  曹代勇  赵珍梅  范建纬 《物探与化探》2012,(1):33-38

笔者旨在依靠重磁、遥感、GIS信息综合分析等技术手段,从宏观裂缝描述、成因分析、发育规律等方面开展多尺度碳酸盐岩裂缝发育区线性异常的综合研究,寻找不同尺度断裂、裂缝间的空间关系,作出对储层裂缝方位及发育带的预测。提出了运用重磁与遥感多元信息复合技术进行裂缝解释的思路和方法,以哈萨克斯坦阿克纠宾地区扎纳若尔和俄罗斯尤罗伯钦—托霍姆碳酸盐岩油田为例,阐明了地球物理线性异常反映的断裂和宏观裂缝的表征意义,剖析了线性异常数量化分析方法,研究了地球物理场和线性异常的分布特征,建立了研究区宏观裂缝发育模式。  相似文献   

基于Hilbert-Huang变换的探地雷达信号增强及复信号分析     

冯德山  余凯  戴前伟 《物探与化探》2012,36(6):975-980

阐述了Hilbert-Huang变换原理,着重讨论了EMD分解应满足的条件及具体分解过程.以黑麋峰抽水蓄能电站进厂交通隧洞实测GPR剖面为例,应用EMD分解去除部分噪声,再利用Hilbert变换求取GPR剖面复信号,提取瞬时振幅、瞬时相位、瞬时频率3个参数,绘制出相互独立的瞬时参数剖面图,根据不同地质状况进行多参数综合解释.结果表明,该方法避免了使用单一时距剖面分析所造成的解释偏差,能够更好地对异常信息做出反映,提高了GPR数据的解析精度.  相似文献   

基于波形切除反褶积的探地雷达信号处理效果     

石刚  田养军  杨晓华 《物探与化探》2012,36(6):981-984

探地雷达接收天线通常采用超宽频带进行记录,接收信号中含有多种干扰.为了消除探地雷达记录中的多次波干扰,提高信噪比,提出了将波形切除反褶积应用于探地雷达信号后处理的方法,提高了记录的纵向分辨率.阐述了该方法的原理和实现过程,分析了适用范围和应用条件.模型试验的结果表明雷达信号的多次干扰和随机干扰明显得到压制,图像效果明显得到改善.  相似文献   

连续小波变换在探地雷达信号分析中的应用研究     

黄敏  朱德兵  郭政学  王树敏 《物探化探计算技术》2012,34(5):593-598,503

广泛应用于工程勘探的探地雷达,由于其发射的高频电磁波在介质中迅速衰减、受环境噪声大等因素影响,探测剖面难以对相对较深的异常体有较好的响应.复信号分析提取三瞬参数可多角度分析信号,并能突出弱反射信息,但易受噪声干扰,且常规的滤波方法不能有效地去除这一干扰.将具有时～频双重局限性的小波变换引入到复信号分析中,解决了复信号分析易受噪声干扰的问题,恢复了其对异常提取的能力.将此算法用于实际雷达探测数据处理中,取得了良好的应用效果.  相似文献