瞬变波活动与江淮地区夏季旱涝的关系   总被引：3，自引：0，他引：3  

董丽娜  郭品文  李晓峰 《南京气象学院学报》2006,29(4):470-476

利用1951-2000年中国160站逐月降水量资料划分了江淮地区夏季旱涝年。通过对旱涝年500hPa高度距平场的合成分析发现：多雨年鄂霍茨克海阻塞高压稳定维持，少雨年鄂霍茨克海附近的高压脊减弱。为了了解江淮地区旱涝年500hPa中高纬环流形势异常的原因，计算了Eliassen-Palm通量，结果表明多雨年瞬变波对平均气流的强迫作用使经、纬向风异常分布有利于鄂霍茨克海阻塞形势的维持，冷空气向南输送增强，江淮地区降水偏多；少雨年瞬变波对平均气流的强迫作用使鄂霍茨克海高压脊减弱，冷空气向南输送减弱，江淮地区降水偏少。  相似文献   

Proterozoic magmatic and tectonometamorphic evolution of the Taratash complex, Central Urals, Russia     

S. Sindern  R. Hetzel  B. A. Schulte  U. Kramm  Yu. L. Ronkin  A. V. Maslov  O. P. Lepikhina 《International Journal of Earth Sciences》2005,94(3):319-335

The Taratash Complex (TC) in the northernmost Bashkirian Anticlinorium (Middle Urals) is unique among the pre-Uralian polymetamorphic complexes along the eastern margin of the East European Craton because it experienced granulite facies peak metamorphic conditions (850–900°C/10 kbar). Herein, we constrain the post-granulite facies polystage evolution of the complex, which records various increments of the geodynamic history of the East European continental margin. Formation of granite and migmatite associated with amphibolite facies events are dated at 2,344±29 and 2,044±8 Ma (U–Pb, zircon) in different structural units. At 1,810±41 Ma, the TC was affected by a greenschist facies retrogressive metamorphism which was probably related to a stage of granite formation in the eastern part of the East European Craton. This is confirmed by a U–Pb–zircon age of 1,848±8 Ma obtained from a sheared granite in the adjacent Alexandrovskiy Complex (AC). Greenschist facies shear zones which separate different structural units of the TC formed before 1,350 Ma. Partial re-equilibration of Rb–Sr- and K–Ar-isotope systems between 1,350 Ma and 1,200 Ma is attributed to fluid flow probably induced by anorogenic magmatism in the Bashkirian Anticlinorium. Meso- to Neoproterozoic basaltic dykes indicate that the TC had been exhumed to upper crustal levels at that time. Evidence for a Grenvillian event or for the Timanian orogeny which affected other pre-Uralian complexes in the Urals is lacking. Uralian orogenic shortening and thrusting on Devonian limestones is recorded by shear zones in the AC to the east of the TC and has been dated at 300 Ma (Rb–Sr, ⁴⁰Ar/³⁹Ar).  相似文献   

北极涛动年代际变化与华北夏季降水的联系   总被引：12，自引：2，他引：12  

李春  罗德海  方之芳  周后福 《南京气象学院学报》2005,28(6):755-762

利用NCEP／NCAR再分析资料和华北夏季降水资料，研究了北极涛动的年代际变化及其与大气环流的关系，进而研究与华北夏季降水异常变化的联系。结果表明，北极涛动具有明显的年代际变化，并在1969年发生了气候突变。北极涛动年代际异常与亚洲中纬度高度场异常、850hPa风场的年代际异常具有很好的一致性。在年代际尺度上，北极涛动与贝加尔湖地区阻塞高压发生频率、东亚夏季风强度和华北夏季降水的关系较为密切。  相似文献   

夏季东北亚阻塞形势维持时的天气尺度波   总被引：6，自引：4，他引：6       下载免费PDF全文

陆日宇 《大气科学》2001,25(3):289-302

利用NCEP/NCAR逐日资料，分析了一次夏季东北亚阻塞形势维持期间(1991年6月27日至7月16日)高频波活动强弱的分布和传播的特征，发现在阻塞高压上 游的巴伦支海上空有明显异常的高频波活跃区，从该活跃区和位于东北大西洋的常年活跃区，高频波不断东传，传到东北亚时，变弱消亡。据此，作者推测高频波的能量传给了阻塞形势，使阻塞形势得以维持。利用Eu矢量分析的高频波能量传播也表明了这一点。此外，利用Eu和Ev矢量讨论了高频波对纬向平均流和经向平均流的反馈强迫作用。结果表明，高频波的强迫作用使得时间平均纬向流在急流分支处呈减弱的趋势。高频波对时间平均的经向流反馈强迫作用更加明显，这种强迫使得急流在阻塞高压的上游产生分支，而在下游产生南北分支气流的汇合。最后，分析了高频波和低频波对热量的南北输送，表明在阻塞期间高频波在东亚地区对流层顶附近产生非常清楚的向北热量输送(冷空气向南输送或暖空气向北输送)，而低频波(可用来表示阻塞流型)的向北热量输送作用表现在对流层中下层，相对来讲不明显。  相似文献   

鄂霍茨克海阻高发展过程的正斜压涡度和涡度拟能的演变特征   总被引：2，自引：0，他引：2  

黄昌兴  周伟灿等 《南京气象学院学报》2001,24(3):356-363

用正斜压分解法，对1998年发生在鄂霍茨克海的阻高进行涡度和涡度拟以分析，结果发现：在阻高的不同阶段，正压涡度和正压涡度拟能远大于斜压涡度和斜压涡度拟能且在不同的阶段有着不同的演变过程；在阻塞的酝酿阶段正压和斜压涡度和涡度拟能不稳定增长，且向西南传播；在维持阶段，正压和斜压涡度和涡度拟能的增长达到最大值，阻塞形势建立并维持在阻塞区域内；在消亡阶段，正压涡度和涡度拟能与斜压涡度拟能则呈现出不稳定减少，向东南传播，阻塞崩溃，然后又增长。  相似文献   

阻塞高压形成、发展机理问题概述   总被引：1，自引：0，他引：1  

王亚非  倪允琪 《南京气象学院学报》2001,24(3):437-445

概要叙述了现代阻塞高压理论的主流，将其概括成5种主要流派，并作简要评论，最后阐明了阻高理论的发展方向。  相似文献   

北京市深井人工回灌现状调查与前景分析   总被引：16，自引：2，他引：16  

孙颖  苗礼文 《水文地质工程地质》2001,28(1):21-23,48

北京市地下水人工回灌研究始于1965年。1981年开始生产性深井人工回灌。由于种种原因，至1999年底实际回灌单位由64个缩减至13个。其间累计回灌量为10734.37×104t。据调查，停灌原因主要有回灌单位停产、转产、回灌井被占，回灌井阻塞，泵改调频，单位搬迁和改换制冷设备等。本文通过对北京市三十几年来地下水人工回灌工作的总结，分析了人工回灌在近年来发展停滞的原因，并对其在城市可持续发展建设中的节水潜力和今后的发展前景作出了论述。  相似文献   

考虑供需随机性的道路交通系统震害引发损失期望评估   总被引：6，自引：0，他引：6  

陈艳艳  王光远 《世界地震工程》2003,19(1):25-30

借鉴可靠度理论，通过震后交通需求及道路震后通行能力的随机性分析并考虑灾后不同阶段的交通供需特性，进行交通系统震后阻塞发生的概率分析及引发损失期望预测，从而为抗震加固决策及震后交通管理及修复提供依据。  相似文献   

Thermotectonic evolution of the western fold-and-thrust belt, southern Uralides, Russia, as revealed by apatite fission track data     

U. A. Glasmacher  G. A. Wagner  V. N. Puchkov 《Tectonophysics》2002,354(1-2)

The Uralides, a linear N–S trending Palaeozoic fold belt, reveals an intact, well-preserved orogen with a deep crustal root within a stable continental interior. In the western fold-and-thrust belt of the southern Uralides, Devonian to Carboniferous siliciclastic and carbonate rocks overlay Mesoproterozoic to Neoproterozoic sedimentary rocks. Deformation in the Devonian, Carboniferous and Permian caused thick-skinned tectonic features in the western and central parts of the western fold-and-thrust belt. A stack of several nappes characterizes the deformation in the eastern part. Along the E–W transect AC-TS'96 that crosses the western fold-and-thrust belt, apatite fission track data record various stages of the geodynamic evolution of the Uralide orogeny such as basin evolution during the Palaeozoic, synorogenic movements along major thrusts, synorogenic to postorogenic exhumation and a change in the regional stress field during the Upper Jurassic and Lower Cretaceous. The Palaeozoic sedimentary cover and the Neoproterozoic basement of the Ala-Tau anticlinorium never exceed the upper limit of the PAZ since the Devonian. A temperature gradient similar to the recent one (20 °C/km) would account for the FT data. Reactivation of the Neoproterozoic Zilmerdak thrust was time equivalent to the onset of the Devonian and Carboniferous collision-related deformation in the east. West-directed movement along the Tashli thrust occurred in the Lower Permian. The Devonian and Carboniferous exhumation path of the Neoproterozoic siliciclastic units of the Tirlyan synclinorium mirrors the onset of the Uralian orogeny, the emplacement of the Tirlyan nappe and the continuous west-directed compression. The five main tectonic segments Inzer Synclinorium, Beloretzk Terrane, Ala-Tau anticlinorium, Yamantau anticlinorium and Zilair synclinorium were exhumed one after another to a stable position in the crust between 290 and 230 Ma. Each segment has its own t–T path but the exhumation rate was nearly the same. Final denudation of the western fold-and-thrust belt and exhumation to the present surface probably began in Late Tertiary. In Jurassic and Cretaceous, south-directed movements along W–E trending normal faults indicate a change in the tectonic regime in the southern Uralides.  相似文献   

硫矿开发简史     

郝尔宏  王庚亮 《化工矿产地质》1997,(1)

硫矿开发简史关键词硫发现应用史料人类对硫的认识始于公元前。硫的拉丁文名称ｓｕｌｆｕｒ传说来自印度梵文ｓｕｌｖｅｒｅ，含义是鲜黄色。一些古代文献中，也有关于硫黄的记载。古代人们认为硫燃烧所形成的浓烟和强烈的臭味能够驱除魔鬼，他们用硫绘制彩色洞穴，并发现...  相似文献