用甚长基线干涉测量数据检测冰期后地壳回弹   总被引：2，自引：0，他引：2       下载免费PDF全文

朱新慧  孙付平 《地球物理学报》2005,48(2):308-313

本文利用甚长基线干涉测量（VLBI）技术提供的实测站速度和地球物理模型ICE_4G提供的数据,采用实测站速度法和基线长度变化率法分别检测了冰期后地壳回弹的垂直运动和水平运动.对用空间技术求解的实测值和用ICE_4G模型求解的估计值进行线性拟合和相关分析,两者的相关系数达到08～09,表明空间技术已经能够检测1～10mm/a的冰后回弹运动;在方向上两者基本一致,在量级上,实测结果的绝对值比模型估计值系统性的偏大约20%,表明当前冰期后的地壳回弹运动比地质时期要猛烈.  相似文献   

Runoff variations in the Luanhe River Basin during 1956–2002     

LI Jianzhu  FENG Ping 《地理学报》2007,17(3):339-350

The decrease of runoff in the Luanhe river basin, which caused water crisis in Tian-jin for several times, was investigated using discharge data covering the period 1956–2002. The data from the differential integral curves of the annual runoff indicate that the decreasing point began in 1979 in the six sub-basins. The decrease of runoff in the Luanhe river basin resulted from the combination of climate effects and human activities, in which the latter plays an important role. This can be illustrated by noting that after 1979 the runoff generated by similar precipitation decreased under the condition that the total precipitation did not decrease in the entire basin. As a result, the annual runoff of the Luanhe river basin after 1979 de-creased by about 6.46×108 m3 each year. To analyze the runoff characteristics, it is inade-quate to seek the runoff trends only and the identification of cyclical component of the runoff as accurate as possible is necessary. From the natural annual runoff discharge time series, we can see the annual runoff fluctuates around the long-term average. Analyzed by VRL (Variable Record Length) method, the main periods of 3, 5–6, 7, 9, 16–20 and 37–39 years were found. The last decade causing water crisis was the driest period in the history, and this condition will last several years from trend analysis and power spectrum analysis. So finding new water sources is urgent to  相似文献   

日长变化、大气角动量和ENSO:1997～1998厄尔尼诺和1998～1999拉尼娜信号   总被引：3，自引：0，他引：3  

周永宏  郑大伟  廖新浩 《测绘学报》2001,30(4):288-292

采用1970年1月－1999年6月期间日长变化序列（ΔLOD）、大气角动量（AAM）和南方涛动指数（SOI），通过小波变换等方法研究ΔLOD、AAM与ENSO间的关系。结果表明，ΔLOD和AAM的年际变化与ENSO具有相似的时变谱结构，从日长和AAM资料中可以检测到1997－1998年厄尔尼诺（El Nino)和1998－1999年拉尼娜（La Nina)事件的信号。  相似文献   

龙陵大震震型及有关问题讨论   总被引：1，自引：0，他引：1       下载免费PDF全文

秦保燕  荣代潞  李启成 《地震工程学报》1993,15(4):23-29

本文根据１９７６年龙陵大震三次主震由南向北的迁移特征以及３次主震及其强余震活动所反映的震源时空分别位于不同的震源区，但首尾相接，且各自有前震和余震。用立交模式和深部剪切蠕滑断层对龙陵大震发生在完整的花岗岩体内作了解释。用介质相对完整、区域压力大解释了主震发生时形成复式震源，以及余震相对发育持特征，对于复式震源提出了用各震源提出了用各震源断层长度累计总和求震级的方法。  相似文献   

Simulated Airborne Flux Measurements in a LES generated Convective Boundary Layer     

M. Schröter  J. Bange  S. Raasch 《Boundary-Layer Meteorology》2000,95(3):437-456

One aim of past boundary-layer experiments with aircraft was the determination of areally averaged heat fluxes. In spite ofsophisticated instrumentation the measured fluxes extrapolated to the ground differed significantly from fluxes measured directly at ground stations. This studypresents simulated sensible heat flux measurements with aircraft flightsthrough a synthetic convective boundary layer created by a401 × 401 × 42 cubic-grid large eddy simulation (LES) with agrid spacing of 50 m. After some considerations with respect to necessary measurement lengths using results ofLenschow and Stankov (1986 – J. Atmos. Sci. 43, 1198–1209), simulated measurementcampaigns were carried out in three modelruns. During each model run five sets ofmeasurement runs were carried out successively.During each set of runs 10 aircraftflew at 10 altitudes with a ground speedof 100 m s^-1 simultaneously throughtime and space. In total, 150 legs were carried out, 15 at each flight level. The resulting`measured' heat fluxes were compared withthose of the `true' flux profiles obtaineddirectly from the ensemble-averagedLES-generated data. No significant systematic error between `measured' and `true' profiles was observed. Furthermore, the comparison of the resulting relative error with the theory ofLenschow and Stankov showed a good agreement at allmeasurement levels.  相似文献   

溃屈型滑坡滑动面切层段对稳定性的影响研究   总被引：1，自引：1，他引：0  

李树森  朱冬林  聂德新  符文熹  任光明 《地质灾害与环境保护》1999,10(1):39-41

在溃有坡滑动面顺层和切层段强度参数关联性研究的基础上,进一步研究发现,切层段滑动面的长度、角度变化,对滑坡稳定性有明显的影响,这种变化,对滑坡稳定性评价及滑坡的工程治理意义较大。  相似文献   

Scaling of fault attributes: A review   总被引：3，自引：0，他引：3  

Anita Torabi  Silje Støren Berg 《Marine and Petroleum Geology》2011,28(8):1444-1460

The present paper reviews our current understanding of fault dimensions and their scaling laws, with special focus on faults in siliciclastic rocks. The aim is to provide a comprehensive overview of recent research in order to identify strengths and challenges related to the way this topic is being addressed. We here investigate the statistical distributions of different fault attributes, e.g. fault length, displacement, damage zone width, core thickness at different scales and tectonic regimes. Biases related to sampling (resolution effect) and statistical visualization of data are discussed. The interrelationship between different faults attributes is addressed, e.g. fault displacement versus length, and fault core thickness and fault damage zone width. The results of this study show that global statistical relationships for fault attribute populations may not be valid, since the fault attributes at different scales behave differently and the compiled data on fault displacement-length exhibit breaks in the transition between faults at different scales, i.e. from small to medium scale faults at ∼1 m displacement and from medium to large scale faults at ∼1000 m displacement. This may also be the case for fault displacement-core thickness and fault displacement-damage zone width, as slight variation in the relationship can be observed between attribute populations derived from small- and medium-size faults at ∼1 m displacement. These differences may indicate the existence of characteristic length scales in fault populations, which could imply a hierarchical ordering of fault systems. The majority of data in our compiled database show no clear distinction between rocks from different lithologies and tectonic settings. Finally, the mechanical aspects of the processes of faulting with respect to the scaling relationships are discussed. Conceptual diagrams for the evolutionary processes of faulting at different scales based on the observed relationships on the plotted datasets of faults’ main attributes (fault displacement, length, core thickness and damage zone width) are proposed.  相似文献   

Dominant spatial variability scales from observations around the Hawaiian Islands     

Dax Matthews  Brian PowellRalph Milliff 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(10):979-987

We utilize a variety of available observations with a semivariogram technique to quantify the oceanic variability around the Hawaiian Islands. The Hawaiian Islands have a significant impact on the North Pacific circulation, and quantifying the characteristics of the variability is important for understanding the eddy energy, as well as required for statistical techniques to work with the data, such as optimal interpolation, data assimilation, etc. Both satellite sea surface height and temperature data are used to determine horizontal scales of variability, while Argo profiles, ship-borne profiles, and autonomous Seagliders provide estimates of the vertical scales. In the lee of the islands, satellite data reveal an increase in horizontal variability attributed to enhanced eddy activity that persists for over 1000 km westward; however, only within 400 km of the immediate lee the horizontal length scales are greatly reduced. Further west, length scales increase significantly indicating a change in the generation mechanism for eddy variability and where eddies merge and coalesce. The meridional length scale gradient is found to be larger than previous results and more representative of the gradient of the first baroclinic mode of the internal Rossby radius. Vertical length scales are shown to increase in the lee, with vertical temperature variability doubled from the windward side.  相似文献   

水下彩色图像传输的信号调制及信道压缩编码设计研究     

余丽敏  程恩  林耿超 《海洋技术学报》2001,20(4):29-32

就水下彩色图像传输这一研究课题，提供了其调制和传输控制部分的DSP解决方案，详细分析了针对水声信道这一特殊传输介质，所采用的特殊调制方法和传输发送机理，并提供了硬件原理图及相应的软件算法流程。  相似文献   

功率谱分析中几个重要问题的讨论     

王强  么枕生 《地理学报》1990,45(3):363-372

本文从理论上推导了谱分析中最大后延M的取值,并且从理论和实际计算中得出了样本长度和其隐含周期之间的关系。只要抽样是平稳的,样本长度并非一定要求太长,仅略为超过其隐含周期的长度即可。但谱分析绝非是万能的。如果样本中仅含有两个波动,且当这两个波动的周期相差一个整数倍或更大时,这两个波动才可以通过谱分析分辨出,反之就会歪曲了其隐含周期。由此可见,在具体应用时,应作一些滤波和去掉趋势是必要的。因而这将对广大气象、地理科学工作者以及其它相邻学科的科研工作者具有重要的参考价值。  相似文献