辐射雾的大气边界层特征   总被引：16，自引：0，他引：16  

黄建平  朱诗武  朱彬 《南京气象学院学报》1998,(2)

利用ＡＤＡＳ对一次连续５天辐射雾进行探测,获得了辐射雾生消过程中的温度、湿度、风场等要素的垂直分布。通过对这些资料的详尽分析,讨论了辐射雾在不同发展阶段的边界层特征。结果表明：逆温层对雾的形成和维持起着重要的作用,而雾又对大气边界层中的温、湿、风结构产生重要影响。  相似文献   

山东枣庄地区辐射逆温及其影响   总被引：1，自引：1，他引：0  

郑全岭  崔秀兰 《气象科学》1998,18(2):156-161

本文运用1981年11月17日-12月16日共30天实地考察资料,分析了山东枣庄地区冬季辐射逆温时空变化规律。并探讨了辐射逆温的生成与云量、风速的关系。  相似文献   

层状介质弹性参数反演问题研究综述   总被引：9，自引：3，他引：6  

宋海斌  张关泉 《地球物理学进展》1998,13(4):67-78

地震波动方程反问题的研究具有重要的理论意义和实践意义。由于高维波动方程反演问题理论研究的困难和巨大的计算量,层次介质弹性参数研究在数学界和地球物理学引起了广泛的关注。经过前人近三十年的努力,一维声波方程的单参数反演理论已趋成熟,并已逐步实用化。基于矢量波动方程的多参数反演,非脉冲响应对应的反问题是层状介质弹性参数反演需要进一步深入研究的问题。  相似文献   

南北带北段地壳上地幔密度与磁性结构     

殷秀华  黎益仕  刘占坡 《大地测量与地球动力学》1998,(4)

利用对应分析约束下的重磁联合反演方法,计算了南北带北段４条地震测深剖面的地壳上地幔的密度和磁化率物性参数。结果表明：①自上而下区内存在中新生界地层与下伏地层（０．１４～０．３０ｇ／ｃｍ３）、中上地壳与下地壳（０．１０～０．２０ｇ／ｃｍ３）和下地壳与上地幔顶部之间（０．３０～０．４０ｇ／ｃｍ３）３个密度分界面;②区内磁性参数随深度增加而增大,浅部中新生界地层几乎无磁性,中上地壳磁化率一般为１００～１５０００×１０－６ＩＳ;下地壳磁性层磁化率明显升高,一般为１５０００～２００００×１０－６ＩＳ;③区内地壳各构造层的密度和磁化率存在明显的横向变化,其分区特征与大地构造分区基本一致。  相似文献   

Aseismic fault movement before the 1995  Kobe earthquake detected by a GPS survey: implication for preseismic stress localization?     

Shaorong Zhao  & Shuzo Takemoto 《Geophysical Journal International》1998,135(2):595-606

By inversion analysis of the baseline changes and horizontal displacements observed with GPS (Global Positioning System) during 1990–1994, a high-angle reverse fault was detected in the Shikoku-Kinki region, southwest Japan. The active blind fault is characterized by reverse dip-slip (0.7±0.2  m yr⁻¹ within a layer 17–26  km deep) with a length of 208±5  km, a (down-dip) width of 9±2  km, a dip-angle of 51°±2° and a strike direction of 40°±2° (NE). Evidence from the geological investigation of subfaults close to the southwestern portion of the fault, two historical earthquakes ( M _L=7.0, 1789 and 6.4, 1955) near the centre of the fault, and an additional inversion analysis of the baseline changes recorded by the nationwide permanent GPS array from 18 January to 31 December 1995 partially demonstrates the existence of the fault, and suggests that it might be a reactivation of a pre-existing fault in this region. The fact that hardly any earthquakes ( M _L>2.0) occurred at depth on the inferred fault plane suggests that the fault activity was largely aseismic. Based on the parameters of the blind fault estimated in this study, we evaluated stress changes in this region. It is found that shear stress concentrated and increased by up to 2.1 bar yr⁻¹ at a depth of about 20  km around the epicentral area of the 1995 January 17  Kobe earthquake ( M _L=7.2, Japan), and that the earthquake hypocentre received a Coulomb failure stress of about 5.6 bar yr⁻¹ during 1990–1994. The results suggest that the 1995  Kobe earthquake could have been induced or triggered by aseismic fault movement.  相似文献   

Inversion for multiple parameter classes   总被引：2，自引：0，他引：2  

B. L. N. Kennett  & M. Sambridge 《Geophysical Journal International》1998,135(1):304-306

Many geophysical data, such as the frequencies of the free oscillations of the Earth, depend on more than one type of model parameter. For inverse problems depending on multiple parameter classes, an iterative solution procedure is introduced in which each parameter class can be treated in the same way. This approach has considerable advantages where a large number of parameters are employed, but can still be useful for smaller systems.
  The iteration by parameter class commences by solving for the direct dependence on a particular parameter class, and at subsequent iterations the cross-dependences between classes are introduced. The update affects only the right-hand side of the equations, and, because the same sets of equations have to be solved at each iteration, an efficient computational implementation can be made. The largest set of equations that has to be solved at a time corresponds to the number of variables in an individual parameter class rather than the full set of parameters, which confers substantial computational benefits for very large problems.  相似文献   

Non-linear inversion using general measures of data misfit and model structure   总被引：3，自引：0，他引：3  

Colin G. Farquharson  & Douglas W. Oldenburg 《Geophysical Journal International》1998,134(1):213-227

We investigate the use of general, non- l ₂ measures of data misfit and model structure in the solution of the non-linear inverse problem. Of particular interest are robust measures of data misfit, and measures of model structure which enable piecewise-constant models to be constructed. General measures can be incorporated into traditional linearized, iterative solutions to the non-linear problem through the use of an iteratively reweighted least-squares (IRLS) algorithm. We show how such an algorithm can be used to solve the linear inverse problem when general measures of misfit and structure are considered. The magnetic stripe example of Parker (1994 ) is used as an illustration. This example also emphasizes the benefits of using a robust measure of misfit when outliers are present in the data. We then show how the IRLS algorithm can be used within a linearized, iterative solution to the non-linear problem. The relevant procedure contains two iterative loops which can be combined in a number of ways. We present two possibilities. The first involves a line search to determine the most appropriate value of the trade-off parameter and the complete solution, via the IRLS algorithm, of the linearized inverse problem for each value of the trade-off parameter. In the second approach, a schedule of prescribed values for the trade-off parameter is used and the iterations required by the IRLS algorithm are combined with those for the linearized, iterative inversion procedure. These two variations are then applied to the 1-D inversion of both synthetic and field time-domain electromagnetic data.  相似文献   

Two-dimensional non-linear inversion of VLF-R data using simulated annealing   总被引：2，自引：0，他引：2  

S.P. Sharma  & P. Kaikkonen 《Geophysical Journal International》1998,133(3):649-668

The VLF-R (very low frequency-resistivity) data, i.e. the apparent resistivity ( ρ _a ) and phase ( φ ) data, were inverted individually and jointly using the VFSA (very fast simulated annealing) global inversion approach. Global inversion results for synthetic data without and with various amounts of random and normally distributed Gaussian noise reveal that the inversion of neither the ρ _a nor φ data alone yields the true parameters of the structures. However, the joint inversion of the ρ _a and φ data yields very good estimates of the model parameters. Five models, representing typical subsurface structures in the shield areas, are studied here. Various models achieved after 10 VFSA runs were used to compute the mean model and the corresponding covariance and correlation matrices, which were used to estimate the uncertainties in the mean model parameters and correlations between the model parameters. We observe that these correlations follow the physics associated with the problem. VLF-R field data due to a nearly vertical contact structure and a very thick dyke-like structure were also inverted to demonstrate the efficacy of the approach in the delineation of the parameters of 2-D structures.  相似文献   

模型反演折射静校正方法及软件技术     

戴云  钟本善  江玉乐 《矿物岩石》1998,(Z1)

本文叙述了模型反演折射静校正的一般原理。首先介绍了折射初至波的自动拾取,其次介绍了最佳拟合旅行时反演。在软件实现中本文提出了几项技术包括提高初至拾取的准确率及初至结果的质量评价,如何使系统对不同地震数据格式具有通用性;静校效果的初步评估。本文的方法和技术在实际生产应用中广泛使用。  相似文献   

青海玉树Mw6.9级地震震源破裂过程     

王洵  周云  孙蒙  王卫民 《地质通报》2014,33(4):517-523

针对2010年青海玉树藏族自治州发生的Mw6.9(Ms7.1)级地震,利用地震波形资料和InSAR获取的同震位移资料,根据同震形成的地表位移干涉图,构建三段式断层模型,反演重建地震的破裂过程。研究显示本次地震断层面走向为119°,倾角79°,滑动角-2.2°,最大滑动量达到200cm,震源深度12.5km,地震标量地震矩为2.18×1026dyn·cm。震源破裂特征表明,玉树地震主要是沿甘孜—玉树断裂发生的左旋走滑破裂事件,反映了印度板块向北的推挤作用下,青藏高原东部不同次级块体东向不均匀挤出的运动学特征。  相似文献