使用因子分析方法研究吉林前郭地震前的地震活动异常   总被引：1，自引：1，他引：0  

李永振  于笑非  郭晓燕  乔艳芬 《东北地震研究》2009,25(2):23-28

本文用2006年吉林前郭MS5.0级地震前后震中附近的地震资料,选择反映地震活动时、空、强特征的地震频次N（ML≥3.0）、b值、η值、A（b）值、Mf值、Ac值、C值和D值8个参量进行因子分析。这些参量之间有一定的相关性,各参量在不同时段的变化各有所异,预报效果并不理想。根据因子分析得到反映地震活动时、空、强特征的综合指标Wfa值,该指标在前郭MS5.0级地震前出现明显异常变化,表明综合指标Wfa值可以较好地反映地震活动的异常特征。  相似文献   

黄河流域上游降水时空结构特征   总被引：23，自引：2，他引：21  

杨志峰  李春晖 《地理科学进展》2004,23(2):27-33

黄河兰州以上区域水资源量占黄河流域水资源的一半以上,研究黄河上游兰州以上区域降水时空结构变化具有重要意义。本文利用黄河兰州以上19个降水站点1959~1998年系列数据,采用EOF技术分析了黄河上游降水的时空结构特征与变化。结果表明：黄河上游兰州以上区域降水存在四种典型降水类型,即“全部一致型”、“南北型”、“东西型”和“相间复杂型”。但第一特征向量为主导,其时间变化系数与年降水量基本一致,说明黄河流域兰州以上降水主要受青藏高原大尺度气候影响,具有降水偏多（少）一致性特征。从时间尺度上降水有减少的趋势;并伴随3、6、和11年的周期变化,而且在1986和1991年发生突变。  相似文献   

Spatio-Temporal Correlation Analysis of Global Temperature Based on the Correlation Matrix Theory   总被引：1，自引：0，他引：1       下载免费PDF全文

ZHI Rong  FENG Guolin  ZHOU Lei  GONG Zhiqiang 《Acta Meteorologica Sinica》2010,24(2):150-162

TBased on the NCEP/NCAR reanalysis daily mean temperature data from 1948 to 2005 and random time series of the same size, temperature correlation matrixes (TCMs) and random correlation matrixes (RCMs) are constructed and compared. The results show that there are meaningful true correlations as well as correlation "noises" in the TCMs. The true correlations contain short range correlations (SRCs) among temperature series of neighboring grid points as well as long range correlations (LRCs) among temperature series of different regions, such as the El Ni o area and the warm pool areas of the Pacific, the Indian Ocean, the Atlantic, etc. At different time scales, these two kinds of correlations show different features: at 1-10-day scale, SRCs are more important than LRCs; while at 15-day-or-more scale, the importance of SRCs and LRCs decreases and increases respectively, compared with the case of 1-10-day scale. It is found from the analyses of eigenvalues and eigenvectors of TCMs and corresponding RCMs that most correlation information is contained in several eigenvectors of TCMs with relatively larger eigenvalues, and the projections of global temperature series onto these eigenvectors are able to reflect the overall characteristics of global temperature changes to some extent. Besides, the correlation coefficients (CCs) of grid point temperature series show significant temporal and spatial variations. The average CCs over 1950-1956, 1972 1977, and 1996 2000 axe significantly higher than average while that over the periods 1978-1982 and 1991 1996 are opposite, suggesting a distinctive oscillation of quasi-10-20 yr. Spatially, the CCs at 1- and 15-day scales both show band-like zonal distributions; the zonally averaged CCs at 1-day scale display a better latitudinal symmetry, while they are relatively worse at 15-day scale because of sea-land contrast of the Northern and Southern Hemisphere. However, the meridionally averaged CCs at 15-day scale display a longitudinal quasi-symmetry.  相似文献   

构造准则矩阵的逆特征值法     

周雄 《测绘学报》1995,24(2):31-37

当用准则矩阵进行控制网二类优化设计时，主要问题之一就是如何给定合理的准则矩阵，近年来发展起来的矩阵逆特征值理论给我们提供了新的解决办法。考虑到从优化的目的出发能够事先确定部分特征信息（特征值和特征向量等等）。本文提出应用逆特征理论构造准则矩阵的新方法，并通过算例说明了整个构造过程，最后给了应用实例。  相似文献   

Efficient Anomalous Forcings for Linear Problems     

Li Zhijin  Ji Liren 《大气科学进展》1994,11(4):436-446

For linear forcing problems, a method is developed to provide a set of forcing modes which form a complete orthonormal basis for the finite-time response to steady forcing in the energy inner product space. The forcing modes are found by calculating eigenvectors of a positive definite and symmetric matrix determined from given equations of motion. The amplitude of responses to forcing modes is given in terms of the associated eigenvalues. This method is used in a nondivergent barotropic model linearized about the 300 hPa zonally-varying climatological flow both for northern summertime and wintertime. The results show that the amplitude of response varies considerably with different forcing modes. Only a few of forcing modes associated with the leading eigenvalues, called efficient forcing mode, can excite significant response. The efficient forcing modes possess highly localized spatial structure with wavetrain appearance. Most of the efficient forcings are located to the south of regions of the jet cor  相似文献   

The spatial and temporal characteristics of the seasonal precipitation over India     

K. D. Prasad 《Pure and Applied Geophysics》1985,123(3):468-475

Three extreme cases of seasonal precipitation over 31 contiguous meteorological subdivisions of India were decomposed into orthogonal components using eigenvector technique to examine their spatial and temporal behaviour. The first two eigenvectors combined were found to represent the seasonal precipitation over India to a sufficient high degree of accuracy retaining 90–95 percent of the total variance. These two components show high spatial similarity in all the three cases of the precipitation examined.The first component is characterized by a coherent variation over the area with large coherent variation over the north-east India, Central India and the west coast of India. The coefficients of the component show annual behaviour with the peak values generally reached during July. This component is representative of the summer monsoon (June–September) mode.The second component characterizes out of phase variation in precipitation between Central India, adjoining parts of the area, and peninsular India. The coefficients of the component show the semi-annual oscillation. It appears that the role of the second eigenvector might be to represent regionality of the seasonal march of the monsoon rain.  相似文献   

运动学涡度的理论与实践   总被引：5，自引：0，他引：5  

郑亚东  王涛  张进江 《地学前缘》2008,15(3):209-220

一般剪切作用下,碎斑或顺剪切作用方向向前或逆向旋转向两特征方向或流脊(非旋转方向)靠拢。高应变条件下,二长比大于一特定值的碎斑,当其顺向或逆向旋转至以特征方向为渐近线的双曲线的稳定翼上时,便稳定下来不再旋转。二长比小于该值的碎斑将不断向前旋转。这一特定值位于该双曲线的顶点,相应的临界形态因子(B*)或/和两特征方向间夹角的余弦定义为运动学涡度(Wk)。Wk是确定一相关韧性变形带纯剪切和简单剪切组分相对大小的重要度量,是根据内旋转(涡度)与线应变速率之间的比值而定的数值度量。就变形带而言,一般剪切带的运动学涡度变化为0~1,纯剪切为零,简单剪切为1。这是一非线性尺度,纯剪切和简单剪切各占50%的运动学涡度为0.71,而不是0.5。运动学涡度可通过计算、图解(双曲线网(PHD)、刚性颗粒网(RGN)法、Passchier图解、Wallis图解)、极摩尔圆法和应力或瞬时增量应变方向获得。运动学涡度与有限应变测量相结合很可能是估算一地地壳减薄/伸展量或增厚/缩短量的最佳途径。变形过程中运动学涡度很可能变化,应根据不同时期形成的构造获得相应时期的运动学涡度。  相似文献   

7月西太平洋副高相关分析及预报   总被引：1，自引：0，他引：1  

李德萍  王新功  匡霞  毕超 《山东气象》2005,25(2):8-11

对7月500hPa西太平洋副高的高度场格点历史资料进行EOF分解,在相关普查的基础上,分别建立前5个特征向量所对应的时间系数的预报方程,然后用预报的主成分求得7月西太平洋副高500hPa高度场的预报值,对2003年7月西太平洋副高形势进行试报,并对2003年7月西太平洋副高异常的成因进行了探讨。  相似文献   

主成分分析法在汶川地震预测中的应用   总被引：4，自引：0，他引：4  

李永振 《四川地震》2009,(2):21-25

选择与地震强度有关的3级以上地震频次N（ML≥3．0）、b值、η值、Mf值、C值和A。值等6个参量进行主成分分析,实现对上述参量的有效约简。这6个参量之间有一定的相关性,各参量在不同时段的变化各有所异,但是根据主成分分析可以得到映应地震强度特征的综合指标W,发现该指标W在汶川8．0级大地震前出现明显的异常变化。这表明综合指标可可以较好的反映地震活动的异常特征。  相似文献   

基于ASTER数据矿化蚀变信息提取的主成分特征向量组合模型研究——以内蒙古红旗山地区为例   总被引：2，自引：1，他引：1  

刘李  向雅莉  芦雪 《现代地质》2010,24(2):403-408

内蒙古额济纳旗红旗山地区矿产资源丰富,但地质勘查工作程度不深,且矿体分散,传统找矿方法难以展开,使用ASTER数据针对该地区进行矿化蚀变信息提取。在经典crosta方法基础上,针对该地区出现较多的铁染蚀变、高岭石+绢云母化和绿泥石化3组不同的蚀变矿物,使用相应特征向量组合模型的主成分分析法进行蚀变信息提取工作,圈定了蚀变异常靶区,与实际矿体和蚀变带有较好相关性,体现了ASTER数据在粘土矿化信息蚀变方面的优势,证明该方法在类似地区的遥感矿化蚀变信息提取工作中的可行性。  相似文献