ANTARCTIC SEA ICE AND THE POLAR VORTEX INDEX:TEMPORAL AND SPATIAL CHARACTERISTICS AND THEIR RELATIONSHIP   总被引：1，自引：0，他引：1       下载免费PDF全文

卞林根  陆龙骅  贾朋群 《Acta Meteorologica Sinica》1995,(1)

The cluster analysis method has been used to divide the Antarctic sea ice variation field into 5 sectors.Then,foreach of these sectors,the corresponding indexes of vortex area and vortex intensity on the 500 hPa level have been calcu-lated.These data were used to analyse the temporal and spatial characteristics of both Antarctic sea ice and the vortexindex variations and their relationship.Our results show that substantial differences are presented in the climatic patternand interannual variations of the sea ice data and vortex index in different sectors.The maximum sea ice extent varia-tions appear in sector 1 and sector 4.Oscillation periods of 2—2.5 and 5—7 years exist in the variations of sea ice extentand vortex index in most sectors.A positive trend is only found in sector 1 sea ice extent while the other sectors shownegative trends.The average extent of the Antarctic sea ice as a whole has retreated at a rate of 1.6 latitudes per 100years.The vortex areas for all sectors have decreased.Nevertheless,the vortex intensities in 3 sectors have increased.Therelationship between sea ice and vortex characters in each sector is obvious,but a little complex.Sectors 1 and 5,whichare located in the Southeast Pacific and South Atlantic,are the most sensitive areas in terms of sea ice/atmosphereinteraction.  相似文献   

西昆仑山库地变质橄榄岩的显微构造特征   总被引：4，自引：1，他引：4       下载免费PDF全文

边千韬  林传勇 《地质科学》1995,30(3):275-282

西昆仑山库地变质橄榄岩块是肢解了的震旦纪一早古生代蛇绿岩碎片。变质橄榄岩以残斑结构为主,呈现粗粗结构向残班结构的过渡和残斑结构向板状等粒结构的过渡。此岩石有明显的变形结构,橄榄石变形时的滑移系为{0kl}[100].橄揽石发育有代表高温(800℃以上)的位错构造,也有代表低温的位错构造。表明此变质橄榄岩经受了上地幔环境下发生的高温塑性流变和侵位过程中及侵位后所经受的低温高应变速率条件下的变形。上地幔环境下变形时的差异应力约为80MPa,应变速率约为1.96×10^-12s^-1-7.03×10^-10s^-1.此变质橄榄岩代表由大陆裂谷发展起来的洋盆下的地幔,产出的构造环境为洋脊-裂谷带。  相似文献   

Scale Dependencies of Vegetation and Topography in a Mountainous Environment of Montana   总被引：2，自引：2，他引：2  

Ling Bian  Stephen J. Walsh 《The Professional geographer》1993,45(1):1-11

This research examines the effects of spatial scale on estimating the relationship between vegetation biomass and topography within a portion of Glacier National Park, Montana. The Reflectance/Absorptance vegetation index, developed from processed Landsat Thematic Mapper digital data, is related to three topographic variables obtained through processed Digital Elevation Models: elevation, slope angle, and slope aspect. R² values between the vegetation index and the topographic variables are obtained from regression analyses at a series of aggregated spatial scales. The effective range of spatial scales within which the two sets of variables are spatially dependent and the degree of the spatial dependencies are characterized through semivariance and fractal analyses.  相似文献   

铋的预分离富集   总被引：4，自引：0，他引：4  

谢素原  边归国 《岩矿测试》1993,12(3):228-233

文章就近年来各种预分离富集Bi方法的某些进展作了概述,内容包括氢化物发生法、共沉淀法、萃取法、色谱法和浮选法,收集文献48篇。  相似文献   

西金乌兰晚二叠-早三叠世石英砂岩及其大地构造意义   总被引：12，自引：1，他引：12       下载免费PDF全文

边千韬  沙金庚 《地质科学》1993,28(4):327-335

在西金乌兰发现一套晚二叠一早三叠世的石英砂岩和底砾岩,不整合于晚古生代。蛇绿混杂岩之上。沉积构造、结构、成分和粒度分析结果证明这套石英砂岩为海滩亚相石英砂岩;其物源区大地构造背景为克拉通内陆块,沉积环境为稳定陆块边缘,类似被动大陆边缘。表明本区古特提斯洋于早二叠世末一晚二叠世初基本闭合后,在晚二叠一早三叠世处于相对稳定阶段。  相似文献   

北京地区强对流天气雷达回波特征   总被引：40，自引：11，他引：29  

王令  康玉霞  焦热光  卞素芬  丁青兰 《气象》2004,30(7):31-35

通过近 2年的观测 ,收集了一些新的、不同类型的强天气个例的回波资料。对其中典型个例的分析可以得到北京地区的一些强天气的雷达回波特征。冰雹、雷雨大风回波高度高 ,达 1 2km ,暴雨过程回波高度仅 7km ;冰雹、雷雨大风这类强对流天气的雷达回波移动速度快 ,而局地暴雨的雷达回波移动速度缓慢。通过对多普勒径向速度图的分析 ,可以得出冰雹、雷雨大风与暴雨的动力结构有着明显的差异。地形的影响是显著的  相似文献   

有咸水区深层淡水可持续利用研究     

卞学洛 《地下水》2004,26(2):91-96

天津市东丽区第四系Ⅱ组深层淡水在长期较强开采状态下未发生水位持续下降及大面积深层淡水成化污染,十余年来地层沉降基本消失.该地多年来中更新统淡水及上更新统、全新统咸水水位具有同步不等幅的动态,证明它们之间联系密切,地层中渗透系数小于10-3m/d的历次海侵沉积层及压实的粘土层具有半透膜特性,咸水越流补给第Ⅱ承压含水组的是淡水.适量加大Ⅱ组淡水开采强度,使其产生越流系统,稳定后不会再加大地面沉降.最终使全新统地下水下入渗水位降低,夺取潜水蒸发的水量.在有咸水分布区,地表入渗水是尚没有引起足够重视的可持续利用地下淡水的补给来源.  相似文献   

Application of Fisher method to discriminating earthquakes and explosions using criterion m _b/ M _S     

Bian Yin-ju 《地震学报(英文版)》2005,18(4):441-450

We try to give a quantitative and global discrimination function by studying m _b/M _S data using Fisher method that is a kind of pattern recognition methods. The reliability of the function is also analyzed. The results show that this criterion works well and has a global feature, which can be used as first-level filtering criterions in event identification. The quantitative and linear discrimination function makes it possible to identify events automatically and achieve the goal to react the events quickly and effectively. Contribution No.05FE3018, Institute of Geophysics, China Earthquake Administrtion.  相似文献   

碳循环及对气候变化和人类生存环境的影响   总被引：3，自引：3，他引：3  

张佳华  卞林根  延晓冬  姚凤梅 《气象科学》2006,26(3):350-354

碳循环及全球变暖已成为影响气候变化、人类生存环境和经济共同发展和安全的重大问题,引起了全球科学、政治、外交政策等部门的重视。本文着重探讨碳循环的由来、生态系统与碳循环的科学相关、在碳循环方面,中国需要解决的问题和科学技术方法以及碳循环系统的科学研究方法和改进等问题。  相似文献   

边坡变形破坏模式识别系统的实现     

边亚东  张玉国  常利武 《岩土工程技术》2006,20(3):121-123,146

以岩体结构为最基本的控制因素,同时结合考虑岩性、结构面形态及边坡结构参数等因素实现了边坡变形破坏模式识别系统。系统将模式识别技术与专家系统有机结合,针对五种岩体类型边坡分别进行模式判断;具有与工程结合紧密、能获得定量结果、层次清晰及使用方便等优点。由本系统判断识别的破坏模式与实际破坏模式相符合,说明了系统的实用性和可行性。  相似文献