中国大陆东部地区中强震水位异常的统计特征          下载免费PDF全文

车用太  鱼金子 《地震地质》1992,14(1):23-29

中国大陆东部地区的地震活动以中强震为主。本文在前人工作的基础上用统计学的方法系统分析了该区中强震前地下水位动态异常的形态,时间与空间分布特征及其与地震三要素的关系,由此建立了地震预报的指标,并用1989年10月大同-阳高6.1级地震的实例进行了其信度与预报效能的检验  相似文献   

湖南膨润土矿床成因类型及矿床实例   总被引：1，自引：0，他引：1  

陈民苏  车勤建 《湖南地质》1990,9(2):29-38

根据成矿地质条件及矿床特征,笔者将湖南省膨润土矿床归纳为四种成因类型:即滨海火山碎屑沉积矿床、内陆湖泊沉积矿床、浅海沉积矿床及风化残余矿床。文中对不同成因的矿床特征进行了简要介绍,并对湖南膨润土矿找矿标志进行了初步归纳。最后在全省范围内划分出六个找矿远景区,以期引起同行们的注意。  相似文献   

Characteristics of long period microtremor and validation of microtremor array measurements in inland areas of China     

Ai-lan Che  Teng-yu Zhang  Shao-kon Feng 《山地科学学报》2016,13(11):1910-1922

To study the characteristics of long period microtremor and applicability of microtremor survey,we have made microtremor observations using long period seismometers of the China's mainland from coastal cities like Shanghai and Tianjin through Beijing,Xi'an,to the far inland cities of Lanzhou and Tianshui.The observation shows that the level of power spectrum of long period microtremors reduced rapidly from the coast to the inland area.However,the energy of long period microtremors in Beijing,Xi'an,Lanzhou and Tianshui area are only approximately ten-thousandth to thousandth of that in Shanghai.Aiming at the complexity of the underground structure in the far inland,a series of underground structure models with different distributions were assessed using three-dimensional,dynamic finite element method(FEM) analyses.The results were used to evaluate microtremor survey methods and their limitations with regard to aggregate variability and thickness determinations.Multiple-wave reflections between layers with the change of underground structure distribution occurred,which have significant effect on the performance of the different field approaches.Information over a broad spectrum from which velocity-depth profiles were produced via inversion approaches.Neither the thickness nor the shear waveVelocity V of the subsurface layer inversion results appeared over a large evaluation with increasing slope angle.In particular,when the angle of the model reached 45°,it could not be accurately evaluated using one-dimensional inversion methods.Finally,the array microtremor survey(AMS) was carried out in Shanghai City,China.Although AMS techniques do not have the layer sensitivity or accuracy(velocity and layer thickness) of borehole techniques,the obtained shear wave velocity structure is especially useful for earthquake disaster prevention and seismic analysis.  相似文献   

Field pumping experiments and numerical simulations of shield tunnel dewatering under the Yangtze River   总被引：1，自引：0，他引：1  

Baotian Xu  Changhong Yan  Qian Sun  Yunping Liu  Jian Hou  Shi Liu  Canhui Che 《Environmental Earth Sciences》2016,75(8):715

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Stable water isotopes of precipitation in China simulated by SWING2 models   总被引：1，自引：0，他引：1  

Yanjun Che  Mingjun Zhang  Shengjie Wang  Jie Wang  Yangmin Liu  Fuxian Zhang 《Arabian Journal of Geosciences》2016,9(19):732

The stable water isotope ratio in precipitation is a useful tracer of atmospheric circulation. Such observations, however, are very limited in space and time. To solve this problem, many isotope-enabled general circulation models (GCMs) are used to help the interpretation of isotope proxies. In this paper, several isotope-enabled GCMs released by the second Stable Water Isotope Intercomparison Group (SWING2) were selected to assess the spatial pattern of deuterium (δD) and the deuterium excess (d) of precipitation in China. The isotopic data of the Global Network of Isotopes in Precipitation (GNIP) and the Chinese Network of Isotopes in Precipitation (CHNIP) were also applied to verify the simulations. The results indicate that these models accurately simulate the spatial characteristics of δD and d of precipitation in China. The correlation between the observations and simulations for LMDZ is the highest among these models, while the root-mean-square (RMS) and standard deviation are not perfect. In addition, LMDZ is worse than other models in capturing the low signal in certain regions, such as CAM, GISS_E, and MIROC. For the monthly variation, most SWING2 models underestimate δD of the precipitation but overestimate the value of d, except for isoGSM. The simulated monthly variation of the water isotopes from SWING2 models is in general similar to the observations, and the trend corresponds to the monthly variation in the Northern Hemisphere. Moreover, all models are good at illustrating the temperature and precipitation amount effects, while they exhibit varying skills in interpreting the altitude and continental effects.  相似文献   

基于GIS的山地城市建筑高度控制方法及其应用     

宋利利  陶澈  朱容鑫  金磊 《测绘与空间地理信息》2016,(4):17-19

将自然山体景观的维护作为山地城市建筑高度控制的目标,以研究区域的地表模型(不规则三角网,简称TIN)为基础数据,基于GIS 10.2技术平台,将瞭望点视野中的山脊线下降20%后的高度作为视线高度控制线计算研究区域内建筑高度控制值,以期为山地城市的控制性详细规划和城市设计中的建筑高度控制提供技术参考。最后,以河南省登封市新区为例,应用此方法来绘制该地区的建筑高度控制栅格图。通过设置像元分辨率的大小,本方法也可用于山地城市修建性详细规划中建筑设计方案的比较。  相似文献   

Relative contributions of boundary-layer meteorological factors to the explosive growth of PM<Subscript>2.5</Subscript> during the red-alert heavy pollution episodes in Beijing in December 2016     

Junting Zhong  Xiaoye Zhang  Yaqiang Wang  Junying Sun  Yangmei Zhang  Jizhi Wang  Kaiyan Tan  Xiaojing Shen  Haochi Che  Lu Zhang  Zhouxiang Zhang  Xuefei Qi  Huarong Zhao  Sanxue Ren  Yang Li 《Acta Meteorologica Sinica》2017,31(5):809-819

Based on observations of urban mass concentration of fine particulate matter smaller than 2.5 μm in diameter (PM_2.5), ground meteorological data, vertical measurements of winds, temperature, and relative humidity (RH), and ECMWF reanalysis data, the major changes in the vertical structures of meteorological factors in the boundary layer (BL) during the heavy aerosol pollution episodes (HPEs) that occurred in winter 2016 in the urban Beijing area were analyzed. The HPEs are divided into two stages: the transport of pollutants under prevailing southerly winds, known as the transport stage (TS), and the PM_2.5 explosive growth and pollution accumulation period characterized by a temperature inversion with low winds and high RH in the lower BL, known as the cumulative stage (CS). During the TS, a surface high lies south of Beijing, and pollutants are transported northwards. During the CS, a stable BL forms and is characterized by weak winds, temperature inversion, and moisture accumulation. Stable atmospheric stratification featured with light/calm winds and accumulated moisture (RH > 80%) below 250 m at the beginning of the CS is closely associated with the inversion, which is strengthened by the considerable decrease in near-surface air temperature due to the interaction between aerosols and radiation after the aerosol pollution occurs. A significant increase in the PLAM (Parameter Linking Aerosol Pollution and Meteorological Elements) index is found, which is linearly related to PM mass change. During the first 10 h of the CS, the more stable BL contributes approximately 84% of the explosive growth of PM_2.5 mass. Additional accumulated near-surface moisture caused by the ground temperature decrease, weak turbulent diffusion, low BL height, and inhibited vertical mixing of water vapor is conducive to the secondary aerosol formation through chemical reactions, including liquid phase and heterogeneous reactions, which further increases the PM_2.5 concentration levels. The contribution of these reaction mechanisms to the explosive growth of PM_2.5 mass during the early CS and subsequent pollution accumulation requires further investigation.  相似文献   

Using stable isotopes to identify major flow pathways in a permafrost influenced alpine meadow hillslope during summer rainfall period     

Xiong Xiao  Fan Zhang  Xiaoyan Li  Chen Zeng  Xiaonan Shi  Huawu Wu  Muhammad Dodo Jagirani  Tao Che 《水文研究》2020,34(5):1104-1116

Global warming has leaded to permafrost degradation, with potential impacts on the runoff generation processes of permafrost influenced alpine meadow hillslope. Stable isotopes have the potential to trace the complex runoff generation processes. In this study, precipitation, hillslope surface and subsurface runoff, stream water, and mobile soil water (MSW) at different hillslope positions and depths were collected during the summer rainfall period to analyse the major flow pathway based on stable isotopic signatures. The results indicated that (a) compared with precipitation, the δ²H values of MSW showed little temporal variation but strong heterogeneity with enriched isotopic ratios at lower hillslope positions and in deeper soil layers. (b) The δ²H values of middle-slope surface runoff and shallow subsurface flow were similar to those of precipitation and MSW of the same soil layer, respectively. (c) Middle-slope shallow subsurface flow was the major flow pathway of the permafrost influenced alpine meadow hillslope, which turned into surface runoff at the riparian zone before contributing to the streamflow. (d) The slight variation of δ²H values in stream water was shown to be related to mixing processes of new water (precipitation, 2%) and old water (middle-slope shallow subsurface flow, 98%) in the highly transmissive shallow thawed soil layers. It was inferred that supra-permafrost water levels would be lowered to a less conductive, deeper soil layer under further warming and thawing permafrost, which would result in a declined streamflow and delayed runoff peak. This study explained the “rapid mobilization of old water” paradox in permafrost influenced alpine meadow hillslope and improved our understanding of permafrost hillslope hydrology in alpine regions.  相似文献   

云对地基微波辐射计反演湿度廓线的影响   总被引：3，自引：3，他引：0       下载免费PDF全文

车云飞  马舒庆  杨玲  邢峰华  李思腾 《应用气象学报》2015,26(2):193-202

利用中国气象局大气探测试验基地的L波段探空数据和微波辐射计观测数据,采用MonoRTM辐射传输模型作为正演亮温模型,BP (back propagation) 神经网络作为反演工具,在由亮温反演大气湿度廓线的过程中,添加与样本匹配的云底高度和云厚度信息,建立新的反演模型,使新反演模型得到的反演湿度廓线和未添加云信息的反演湿度廓线分别与探空数据进行对比,获取两种反演方法各高度层的均方根误差,分析云信息对反演大气湿度廓线的影响。对比结果表明:未添加云信息时,测试样本的反演湿度廓线与探空廓线的相关系数平均值为0.685,而添加云信息后,相关系数平均值为0.805。相比未添加云信息的反演廓线,添加云信息之后多数高度层的均方根误差均有不同程度减小,而在有云以上高度层表现尤为明显。  相似文献   

Mapping the permafrost stability on the Tibetan Plateau for 2005–2015     

Youhua RAN  Xin LI  Guodong CHENG  Zhuotong NAN  Jinxing CHE  Yu SHENG  Qingbai WU  Huijun JIN  Dongliang LUO  Zhiguang TANG  Xiaobo WU 《中国科学:地球科学(英文版)》2021,64(1):62-79

Data scarcity is a major obstacle for high-resolution mapping of permafrost on the Tibetan Plateau(TP).This study produces a new permafrost stability distribution map for the 2010 s(2005–2015)derived from the predicted mean annual ground temperature(MAGT)at a depth of zero annual amplitude(10–25 m)by integrating remotely sensed freezing degree-days and thawing degree-days,snow cover days,leaf area index,soil bulk density,high-accuracy soil moisture data,and in situ MAGT measurements from 237 boreholes on the TP by using an ensemble learning method that employs a support vector regression model based on distance-blocked resampled training data with 200 repetitions.Validation of the new permafrost map indicates that it is probably the most accurate of all currently available maps.This map shows that the total area of permafrost on the TP,excluding glaciers and lakes,is approximately 115.02(105.47–129.59)×10^4 km^2.The areas corresponding to the very stable,stable,semi-stable,transitional,and unstable types are 0.86×10^4,9.62×10^4,38.45×10^4,42.29×10^4,and 23.80×10^4 km^2,respectively.This new map is of fundamental importance for engineering planning and design,ecosystem management,and evaluation of the permafrost change in the future on the TP as a baseline.  相似文献