华南大范围暴雨副热带高压的演变特征及可能机制     

李向红 《气象研究与应用》2001,22(3):13-17

利用多时间尺度ＮＣＥＰ／ＮＣＡＲ再分析资料、ＴＢＢ资料，通过合成分析、动力诊断、理论探讨和数值模拟等方法，对华南暴雨发生时副热带高压的短期变异进行了探讨。结果表明，华南暴雨发生前副热带高压有一西伸一东撤的过程，而华南暴雨发生在副高东撤到接近最东时。利用Ｌ９Ｒ１５谱模式模拟了孟加拉湾异常热源对副热带高压西仲的影响，数值模拟结果表明孟加拉湾异常热源可能是副热带高压西伸的可能机制。而正的涡度的局地变化可能是副高东撤的因素。  相似文献   

新疆盐湖卤水成分及其成因   总被引：15，自引：0，他引：15  

郑喜玉  刘建华 《地理科学》1996,16(2):115-123

根据野外考察和室内研究资料，论述了新疆盐湖的概况，卤水主要和次要成分，盐湖的水化学类型。探讨了盐湖卤水化学成分的来源和集散特点。  相似文献   

宏观地震忽略吸收确定震源深度问题的通解及其精确度     

段星北 《地震研究》1992,15(3):271-282

分析G-R-闵公式后得出,它是从点源幅射场导出的,与地震宏观场不相应。因在近场震源不能视作点源。在分析过程中,导出相当于点源、线源或面源以及复杂源的幅射场的深度公式。对实际的地震,它的源类型一无所知,所以不预作假定,将源指标几何扩散率n作为待定参数,导出了一个物理意义明确而又普遍化的震源深度公式。此公式的诸解法中,以计算方法准确、精度高,作图法有直观的优点,但准确性差、精度低,图算法只作获取粗略值和考察数据均匀性用。计算了9个8级以上巨震、1个71/2大震,和两个M_L=3的有感地震的震源深度,经对比结果很好,利用计算得出震源类型,结合宏观场研究了这些地震的震源几何学。并且首次在国际上给出宏观地震震源深度值的标准误差。  相似文献   

矿石源标定射气仪的应用研究     

周永安  唐忠慧 《铀矿地质》1992,8(1):42-47

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One more explanation of superluminal motion     

V. Krishan 《Journal of Astrophysics and Astronomy》1988,9(4):231-236

The occurrence of superluminal motion in extragalactic radio sources is believed to be quite common. Among others, the geometrical scattering of radio radiation can also cause superluminal expansion and or motion and halo formation, In this paper, the effectiveness of the stimulated Raman scattering in producing these features is investigated. The scattering medium is a plasma whose position, density and temperature decide the rate and angle of scattering. When the radiation from a stationary and constant source gets scattered from a stationary plasma, a halo is formed around the source. However, the scattering of a rotating radiation beam does produce superluminal motion of the virtual source. It is found that the plasma should have the characteristics of the emission-line regions and the intercloud medium in order to Raman scatter the radiation. Since the scattering is polarization dependent, it is possible to estimate the rotation of the electric vector along the direction of the apparent motion of a radio source.  相似文献   

新疆阿尔泰南缘泥盆纪多金属成矿带Sr-Nd-Pb同位素地球化学与构造背景探讨   总被引：17，自引：6，他引：17  

万博  张连昌 《岩石学报》2006,22(1):145-152

新疆阿尔泰南缘晚古生代火山岩区分布着多个金属成矿带，其中以阿舍勒成矿带和可可塔勒成矿带最为著名，矿床地质研究表明，产于早-中泥盆统的多金属硫化物矿床大多具有VMS型矿床的特征。通过测定部分典型矿床的Sr-Nd-Pb同位素组成，发现从乔夏哈拉至可可塔勒矿区初始锶逐渐升高，由0．704407到0．714485；而εNd（t）由正值变为负值。反映成矿物质来源以幔源为主，过渡到壳源物质的混入逐渐增加。从Pb同位素特征来看，成矿带内的大多数矿床具有火山岛弧区成矿的特征，矿石铅同位素组成显示正常铅，但可可塔勒铅锌矿床矿石铅具有放射性成因铅的加入。结合成矿带内各主要块状硫化物矿床的地质和地球化学特征，本文认为阿舍勒铜锌矿可能产于与俯冲有关的弧内（弧间）盆地环境，可可塔勒铅锌矿、蒙库铁（铜）矿和铁木尔特铜铅锌矿产于弧后盆地环境。而乔夏哈拉铜铁矿Sr—Nd—Pb同位素组成显示其具有MORB特征，这与其“塞浦路斯型”块状硫化物矿床的特征相吻合。  相似文献   

嵩县上庄坪铜铅锌多金属矿床地质特征及成因分析     

王瑞良 《华南地质与矿产》2007,6(2):14-18

本文着重论述了上庄坪铜铅锌多金属矿床的地质特征和成矿淀化,进行了成因分析。认为含矿岩系的物源主要来自海底火山喷发作用形成的黄铁矿化矿源层。经燕山期构造热液的叠加,驱使矿源层中的成矿元素活化、迁移,在有利的构造部位富集成矿。  相似文献   

废旧放射源的检测方法及其应用     

李亚平 陈曦许正繁  李佳升邓秀文 《岩矿测试》2007,26(5):401-403

根据地勘行业所用放射源的特点，确定了废旧放射源的种类、活度、表面剂量率和表面污染率等参数的检测方法，并将方法应用于对上百个未知放射源进行检测和档案整理，效果较好。  相似文献   

长江—黄河上游源区沼泽湿地遥感动态特征及其成因分析     

沈松平王军  游丽君宋云 《四川地质学报》2007,27(2):142-145

通过两个时像的对比解译、调查验证和研究,表明长江-黄河上游源区20世纪90年代初至21世纪初的10年中,沼泽湿地总体呈减少趋势。由于自然和人为综合因素的长期作用,使本区沼泽湿地处于萎缩状态。  相似文献   

Helium and argon isotopes of the Tertiary basic igneous rocks from Shandong Peninsula and implications for the magma origin   总被引：2，自引：0，他引：2  

TANG HuaYun  ZHENG JianPing?  CHEN HongHan & YE XianRen State Key Laboratory of Geological Processes  Mineral Resources  Faculty of Earth Sciences  China University of Geosciences  Wuhan  China  Faculty of Earth Resources  China University of Geosciences  Wuhan  China  State Key Laboratory of Gas Geochemistry  Institute of Geology  Geophysics  Chinese Academy of Sciences  Lanzhou  China 《中国科学D辑(英文版)》2007,50(7):1021-1032

Helium (He) and Argon (Ar) isotopic compositions of the Tertiary basic igneous rocks were determined by the high temperature melting extraction method. The selected samples for the studies included al-kaline basalts and diabases from the Jiyang basin,and the surrounding Shanwang and Qixia outcrops in the Shandong Peninsula,eastern China. The results show that the Paleogene basalts and diabases from the Jiyang basin yielded a wide range of P4 PHe abundance of (73.70-804.16)×10 P-8 Pcm P3 P STP·g P-1 P,with P3 PHe/ P4 PHe ratios of 0.374-2.959 Ra,which was lower than the MORB but evidently higher than the con-tinental crust value. The Neogene alkaline basalts from the Jiyang basin,Shanwang and Qixia outcrops have variable P4 PHe abundances ((42.34-286.72)×10-8 Pcm P3 P STP·g-1 P),and "continental crust-like" P3 PHe/ P4 PHe ratios (0.013-0.074 Ra). All of them contain atmospheric-like P40 PAr/ P36 PAr ratio (395.4-1312.7),reflecting the mantle sources with air components. Their low P3 PHe/ P4 PHe ratios are interpreted as the enrichment of the radiogenic P4 PHe mainly inherited from the mantle. He and Ar systematics show the mixing of MORB-type,air and a P4 PHe enriched member in the mantle source,suggesting that these igneous rocks originated from the depleted asthenospheric mantle mixed with an EMI component. Therefore,the present He and Ar isotopes do not support the viewpoints that the Cenozoic igneous rocks of Eastern North China were the products of mantle plume(s) activities.  相似文献