都江堰M_L4.4地震前兆异常特征及预报概况          下载免费PDF全文

章旭玲  王翰全  陈明勇 《地震工程学报》1997,19(1):49-53

介绍了１９９３年１２月３０日都江堰ＭＬ４．４地震的前兆异常特征及震前预报概况。震前异常主要有空区、ｂ值、波速比、电磁波等  相似文献   

1995年永登5.8级地震多种前兆异常特征   总被引：3，自引：5，他引：3       下载免费PDF全文

杜学彬  李步云  刘耀炜 《地震工程学报》1997,19(4):19-24

研究了１９９５年７月２２日甘肃永登５．８级地震地电、水化学、水动态、地应力、地形变等５种前兆的异常特征，得到如下结论：①该次地震中短期（１年尺度）和短临异常空间分布符合“异常震源地点发震机制主要活断层”之间的特定关系，近２～３年的中期异常集中分布在西秦岭北缘北西向断裂带和海原通渭武都南北向断裂带上；②震前约１年时间尺度震源区发育起来了北北西南南东向挤压变化突出的附加应力场，并引起断层错动；③源兆集中分布在本次地震震源周围，场兆集中分布在上述两条活动断裂带上．源兆占异常的大多数，场兆占少数．在时间上场兆出现在先，源兆在后．  相似文献   

地震预测研究与展望   总被引：1，自引：0，他引：1       下载免费PDF全文

陈棋福  陈颙  李娟  陈龙生 《地球物理学报》1997,40(Z1):386-395

概要介绍了近年来国际上就地震预测所展开的争论，分析了VAN方法所反映的地震前兆研究动向；就地震前兆观测与数据资料库建设、地震前兆的统计分析、地震的动力学预测、地震预测算法的发展等方面，论述了国际地震预测研究的进展；并概略地介绍了中国的地震预测研究进展．  相似文献   

GRADIENT DISTRIBUTION OF ACID RAIN IN THE SCENIC RESORT OF THE BAIYUN MOUNTAIN IN GUANGZHOU     

黄健  李福娇  江奕光  李琼 《热带气象学报(英文版)》2004,10(1):95-105

1 INTRODUCTION Sitting in the central part of the Pearl River Delta, Guangzhou is one of the cities in China that are most polluted by acid rain. Broad attention has been brought to the problem. Since the early 1980s, a series of observation and studies h…  相似文献   

Scattering Properties of Atmospheric Aerosols over Lanzhou City and Applications Using an Integrating Nephelometer   总被引：2，自引：0，他引：2  

张武  胡波  陈长和  杜萍  张镭  冯广泓 《大气科学进展》2004,21(6):848-856

The data, measured by a three-wavelength Integrating Nephelometer over Lanzhou City during the winters of 2001/2002 and 2002/2003 respectively, have been analyzed for investigating the scattering properties of atmospheric aerosols and exploring their relationship and the status of air pollution. The aerosol particle volume distribution is inverted with the measured spectral scattering coefficients. The results show that the daily variation of the aerosol scattering coefficients is in a tri-peak shape. The average ratio of backscattering coefficient to total scattering coefficient at 550 nm is 0.158; there exists an excellent correlation between the scattering coefficients and the concentration of PM10. The average ratio of the concentration of PM10 to the scattering coefficients is 0.37 g m-2, which is contingent on the optical parameters of aerosol particles such as the size distribution, etc.; an algorithm is developed for inverting the volume distribution of aerosol particles by using the histogram and Monte-Carlo techniques, and the test results show that the inversion is reasonable.  相似文献   

Aerosol polarized phase function and single-scattering albedo retrieved from ground-based measurements     

Zhengqiang Li  Philippe Goloub  Claude Devaux  Xingfa Gu  Yanli Qiao  Fengsheng Zhao  Hongbin Chen 《Atmospheric Research》2004,71(4):233-241

Aerosol optical parameters, polarized phase function and single-scattering albdeo, have been retrieved from ground-based sun photometer measurements in Beijing 2003. The measured aerosol optical thickness varies from 0.12 to 0.77 with an average value of 0.39. The measured Ångström coefficient ranges from 0.75 to 1.47 with an average value of 1.21. The retrieved single-scattering albedo at 870 nm is within the 0.76–0.94 range and the average value is 0.85, suggests there are considerable aerosol absorptions in Beijing. The maximum value of retrieved polarized phase function at 870 nm ranges from 0.068 to 0.225 with an average value of 0.16, and it illustrates good correlations with the Ångström coefficient, i.e. the relative size of aerosol particles. Analyses of measurements and theoretical calculations show the polarized phase function is sensitive to aerosol size distribution and complex refractive index, especially the imaginary part of the refractive index which denotes aerosol light absorbing effects. These results suggest that the polarized phase function is an effective and unique aerosol optical parameter and is able to improve the retrieval of aerosol physical properties.  相似文献   

3-D rheologic model of earthquake preparation (II): Strain field and its applications     

宋治平  尹祥础  梅世蓉 《地震学报(英文版)》2004,17(2):131-143

Introduction Based on the elastic theory of the hard inclusion (Dobrovolskii, 1991), we developed an inclusion theory of rheologic medium, and applied the results of bulk-strain field of a rheologic inclusion model to explain the spatial-temporal evolution process of earthquake precursors (SONG, et al, 2000). In the former paper (SONG, et al, 2003), we derived the viscoelastic displacement field of the rheologic inclusion model on the basis of the analytic expression of displacement field o…  相似文献   

A Review of Research on Human Activity Induced Climate ChangeⅠ. Greenhouse Gases and Aerosols     

王明星  刘强  杨昕 《大气科学进展》2004,(3)

Extensive research on the sources and sinks of greenhouse gases, carbon cycle modeling, and the characterization of atmospheric aerosols has been carried out in China during the last 10 years or so. This paper presents the major achievements in the fields of emissions of greenhouse gases from agricultural lands, carbon cycle modeling, the characterization of Asian mineral dust, source identification of the precursors of the tropospheric ozone, and observations of the concentrations of atmospheric organic compounds. Special, more detailed Information on the emissions of methane from rice fields and the physical and chemical characteristics of mineral aerosols are presented.  相似文献   

北京市春夏季大气气溶胶的单颗粒分析表征   总被引：9，自引：0，他引：9  

肖锐刘成德  梁汉东董树屏 F．Adams 《岩矿测试》2004,23(2):125-131

采集了北京市2000年春夏季大气气溶胶样品5个，采用扫描电镜X射线能谱技术分析大气气溶胶单颗粒约2500个。研究结果表明，沙尘期间，矿物尘是最主要的颗粒物种类，非沙尘期间，北京市大气气溶胶中主要检出矿物尘和含硫颗粒物。夏季随着颗粒物污染的加重，含硫颗粒物的数目百分数增加。是北京市大气颗粒物污染的重要特征。重点讨论了Ca-S颗粒、K-S颗粒和Ca-K-S颗粒三类典型含硫颗粒物的化学组成和粒径分布特征。数目可观的Ca-K-S颗粒以及其他硫酸盐颗粒的生成与相对湿度和云量等气象条件相关，这些颗粒物可能是云中过程的产物。减少SO2排放，减少含硫颗粒物，对于控制北京市的大气颗粒物浓度水平具有重要意义。  相似文献   

Vertical dynamic and thermodynamic characteristics of urban lower boundary layer and its relationship with aerosol concentration over Beijing   总被引：1，自引：0，他引：1  

ZHOU Mingyu  YAO Wenqing  XU Xiangde  YU Haiqing 《中国科学D辑(英文版)》2005,48(Z2)

By utilizing observational data from a 325 m tower of the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS) on March 19-29, 2001 and August 11-25, 2003, a comprehensive study was conducted on the vertical dynamical and thermodynamic characteristics of the urban lower boundary layer (ULBL) and its relationship with aerosol concentration over Beijing. Firstly, a comparative analysis was made on the gradient data (wind, temperature and humidity), ultrasonic data (atmospheric turbulences) and air-quality observations at different tower heights (47, 120 and 280 m). Secondly, a diagnosis was made to reveal the major features of normalized variances of velocity and temperature, turbulence kinetic energy as well as their relationship with aerosol concentrations. Furthermore, the characteristics of the ULBL vertical structure and the TSP concentration/distribution variations during a sand/dust weather process were also analyzed. The outcome of the study showed that under unstable stratification, the normalized variances of velocity (σu/u*, σv/u*, σw/u*) and temperature (σT/T*) at 47 and 120 m heights fit the Monin-Obukhov similarity (MOS) framework and the fitting formulas were given out accordingly. According to the stratification parameter (z′/L), the stable ULBL could be divided into 2 zones. With z′/L<0.1, it was a weakly stable zone and MOS framework was applicable. The other was a highly stable zone with z′/L>0.1 and the normalized velocity variances tended to increase along with higher stability, but it remained constant for normalized temperature variances. At daytime, the near-surface layer includes two heights of 47 and 120 m, while 280 m has been above it. The ULBL analysis in conjunction with a sand/dust weather process in Beijing in March 2001 indicated that the maximum concentration of Total Suspended Particulates (TSP) at 320 m reached 913.3 μg/m3 and the particles were transported from the upper to lower ULBL, which was apparently related to the development process of a low-level jet and its concomitant strong sinking motion.  相似文献