昆仑-巴颜喀拉块体强震前后地震活动性综合参量变化特征   总被引：1，自引：1，他引：0  

王林瑛  韩邵欣  陈学忠 《地震地磁观测与研究》2011,32(6):1-7

以2001年以来2次8级地震和2010年4月青海玉树M7.2地震为例,分析了Rt值在强震前后随时间和空间异常变化特征,同时对综合参量的预测效能进行了检验.结果表明:在强震前Rt值大都出现明显的异常降低过程.在地震综合参数异常和强震关系的研究中,利用地质构造块体约束研究的区域,可以较为清晰地看到强震前后地震活动性异常特征...  相似文献   

湖南省农村土地整治新模式分析     

卫学众 《国土资源导刊(湖南)》2015,(1):55-59

为适应农村土地整治事业发展需要,湖南省结合本省实际,创新土地整治模式,试行"先建后补、以补促建"农村土地整治模式,通过在长沙市望城区和株洲市攸县的项目试点,取得良好的效果。本文采用理论联系实际、对比分析等方法,对该模式形成过程、内涵、运作方式等方面进行全面介绍,并与传统的土地整治模式进行比较分析,提出完善该模式的建议。  相似文献   

Effect of tropical cyclone intensity and instability on the evolution of spiral bands     

Hong Huang  Yongqiang Jiang  Zhongyi Chen  Jian Luo  Xuezhong Wang 《大气科学进展》2014,31(5):1090-1100

The evolution of spiral-band-like structures triggered by asymmetric heating in three tropical-cyclone-like vortices of different intensities is examined using the Three-Dimensional Vortex Perturbation Analyzer and Simulator （3DVPAS） model. To simulate the spiral bands, asymmetric thermal perturbations are imposed on the radius of maximum wind （RMW） of vortices, which can be considered as the location near the eyewall of real tropical cyclones （TCs）. All the three vortices experience a hydrostatic adjustment after the introduction of thermal asymmetries. It takes more time for weaker and stable vortices to finish such a process. The spiral-band-like structures, especially those distant from the vortex centers, form and evolve accompanying this process. In the quasi-balance state, the spiral bands are gradually concentrated to the inner core, the wave behavior of which resembles the features of classic vortex Rossby （VR） waves. The unstable vortices regain nonhydrostatic features after the quasi-balance stage. The spiral bands further from the vortex center, similar to distant spiral bands in real TCs, form and maintain more easily in the moderate basic-state vortex, satisfying the conditions of barotropic instability. The widest radial extent and longest-lived distant bands always exist in weak and stable vortices. This study represents an attempt to determine the role of TC intensity and stability in the formation and evolution of spiral bands via hydrostatic balance adjustment, and provides some valuable insights into the formation of distant spiral rainbands.  相似文献   

地球自转对强震震中附近中小地震的影响     

王恒信  郭祥云  李艳娥  陈学忠  侯海东 《地震地磁观测与研究》2013,(5):52-60

论述2008年5月12日四川汶川Ms8.0地震和2010年4月14日青海玉树Ms7.1地震前震中附近中小地震和地球自转季节性变化的关系,介绍1970年以来中国大陆其他14例M≥7.0地震震例.研究发现,在强震前几年时间内,震中附近地区的中小地震有偏向发生于地球自转速率季节性变化加速或者减速某一阶段的现象.该结果对深入认识地震与地球自转之间的关系具有一定启示意义,对地震预测具有一定指导意义.  相似文献   

2009年中国大陆地区部分地震的震源机制解     

郭祥云  陈学忠 《国际地震动态》2010,(2):13-21

选用国家地震台网和区域台网的初至波P波初动符号资料,采用下半球等面积投影,用格点尝试法计算了2009年中国大陆27次MS4.5级以上地震的震源机制解。根据Zoback[1]研究全球应力场时的分类标准,对断层面解类型进行了分类。结果表明:走滑型(SS)地震13次,逆断层为主兼走滑(TS)8次,逆断层(TF)2次,正断层为主兼走滑(NS)3次,正断层(NF)1次。主压应力轴P轴方位的优势分布具有明显的区域特征,除东北地区有稍微的偏移,其余地区都与当地的背景构造应力场基本一致。  相似文献   

主分量分析在热带气旋强度客观预报中的试用   总被引：3，自引：0，他引：3  

王耀领  胡邦辉  杨玉震  王学忠  徐志春 《气象科学》2010,30(2):179-184

为了解主分量因子分析在热带气旋强度客观预报中的应用效能,在NCEP再分析资料、T106L19模式产品和热带气旋历史观测资料基础上,采用主分量因子分析技术,结合多元线性回归和BP型人工神经网络,开展了西北太平洋热带气旋的强度客观预报技术研究试验。试验包含完全预报法原理下的预报因子有无主分量分析、线性与非线性预报方法建模等方面的比较。结果表明,预报因子的主分量分析通过降低线性回归和BP人工神经网络模型的维数,提高因子间独立性,可减小模型强度预报平均绝对误差,提高模型实际预报能力。  相似文献   

Relationship between Arctic sea ice thickness distribution and climate of China          下载免费PDF全文

王学志  孙照渤  胡邦辉  谭言科  曾刚 《Acta Meteorologica Sinica》2012,26(2):189-204

Based on the simulated ice thickness data from 1949 to 1999,monthly mean temperature data from 160 stations,and monthly mean 1 × 1 precipitation data reconstructed from 749 stations in China from 1951 to 2000,the relationship between the Arctic sea ice thickness distribution and the climate of China is analyzed by using the singular value decomposition method.Climate patterns of temperature and precipitation are obtained through the rotated empirical orthogonal function analysis.The results are as follows.(1) Sea ice in Arctic Ocean has a decreasing trend as a whole,and varies with two major periods of 12-14 and 16-20 yr,respectively.(2) When sea ice is thicker in central Arctic Ocean and Beaufort-Chukchi Seas,thinner in Barents-Kara Seas and Baffin Bay-Labrador Sea,precipitation is less in southern China,Tibetan Plateau,and the north part of northeastern China than normal,and vice versa.(3) When sea ice is thinner in the whole Arctic seas,precipitation is less over the middle and lower reaches of Yellow River and north part of northeastern China,more in Tibetan Plateau and south part of northeastern China than normal,and the reverse is also true.(4) When sea ice is thinner in central Arctic Ocean,East Siberian Sea,Beaufort-Chukchi Seas,and Greenland Sea;and thicker in Baffin Bay-Labrador Sea,air temperature is higher in northeastern China,southern Tibetan Plateau,and Hainan Island than normal.(5) When sea ice is thicker in East Siberian Sea 5 months earlier,thinner in Baffin Bay-Labrador Sea 7-15 months earlier,air temperature is lower over the north of Tibetan Plateau and higher in the north part of northwestern China than normal,and a reverse correlation also exists.  相似文献   

加卸载响应比理论中的海潮校正     

陈学忠  尹祥础 《大地测量与地球动力学》1997,(1)

给出了一种计算海潮负荷在地球内任一点产生的应力场的方法，并由此对加卸载响应比进行了海潮负荷改正。结果表明，在近海地区或海域，海潮负荷对加卸载响应比有影响，离海潮负荷区越近，影响越大；而在离海潮负荷区较远的地区，可以忽略海潮的影响  相似文献   

SIMULATION ON CLIMATIC VARIATION OF ARCTIC SEA ICE THROUGH AN ICE-OCEAN COUPLED MODEL^*          下载免费PDF全文

WANG Xuezhong  SUN Zhaobo  HU Banghui  MIN Jinzhong  ZENG Gang 《Acta Meteorologica Sinica》2004,18(3):347-362

An ocean model developed by the Institute of Marine Research and the University of Bergen in Norway (BOM) and a state-of-the-art sea ice model developed by NCAR (CSIM4) are coupled, Considering influences of 9 major rivers,forced by the NCEP reanalysis atmospheric fields and the Levitus surface salinity,the Arctic sea ice climatic variation from January 1949 to December.1999 was simulated through the coupled model.The comparison of simulated results and observations shows that:(1)the long-term ice concentration variation tendencies are in consistent with the observations in the divisional ocean regions;(2)simulated ice thickness horizontal distribution is reasonable.Simulated ice thickness has a decreasing tendency in the central Arctic,which agrees with the submarine observations.Simulated annually maximum ice thickness is highly related to observed fast-ice thickness off the Russian coast;and (3)sea ice area/volume fluxes through the Fram Strait are in accord with the satellite-derived data.Generally,the coupled model successfully simulated the Arctic Ocean sea ice climatic variation.  相似文献   

2001年昆仑山口西8.1级大地震前后震源区应力水平估计a   总被引：3，自引：2，他引：3       下载免费PDF全文

陈学忠 《地震学报》2005,27(6):605-609

提出了估计地震前后震源区应力水平的方法. 以2001年昆仑山口西8.1级地震为例， 估算了地震前后震源区的应力水平. 结果表明:地震前震源区的应力值为6.3~8 MPa；地震发生后，震源区的应力值为5~6.7 MPa. 震后震源区的应力仅下降了20%左右.   相似文献