欧亚大陆桥(中国段)沿线植被与风沙天气分布的关系分析     

陈添宇  余优森  陈臻妹 《干旱气象》1999,(3)

用３０ 年平均气象资料和夏季ＮＯＡＡ卫星ＡＶＨＲＲ 资料,分析欧亚大陆桥（ 中国段） 沿线的气候、植被特征及其关系。对影响铁路运输的风沙天气等气象灾害资料与沿线植被资料,进行了较深入的对比分析和讨论。  相似文献   

我国东北及邻近地区年平均气温异常及其对北半球气候变暖和欧亚雪盖面积的响应   总被引：2，自引：1，他引：1  

侯依玲  李栋梁  施雅风  沈永平 《冰川冻土》2006,28(6):900-908

根据我国东北及邻近地区201个常规气象台站的年平均气温资料,利用EOF和分段线性拟合等方法分析了该地区气温异常的年代际特征及其对北半球气温和欧亚雪盖面积的响应.结果表明:我国东北及邻近地区年平均气温异常主要有全区一致型和南北反向型两种.近50 a来气温总体呈单调上升趋势,尤其是1990年代后期增温趋势更加明显,时间上东部早于西部.结合降水,1980年代起东北北部由冷干向暖湿转变,而华北区则由暖湿向暖干转变.东北北部升温单调、剧烈、显著,南部在1968和1985年曾两次发生突变,经历过1970-1980年代初的低温后增温趋势更加剧烈,其增温率几乎是第一次突变前的两倍.分析认为,我国东北及邻近地区大范围整体变暖与北半球平均气温的升高相一致;东北部气温的年际变化还受到欧亚雪盖面积的影响.  相似文献   

Scenarios of land cover in Eurasia under climate change   总被引：2，自引：1，他引：1  

Fan  Zemeng  Bai  Ruyu  Yue  Tianxiang 《地理学报(英文版)》2020,30(1):3-17

The method for surface modelling of land cover scenarios(SMLCS) has been improved to simulate the scenarios of land cover in Eurasia. On the basis of the observation monthly climatic data observed from 2127 weather stations in Eurasia during 1981–2010, the climatic scenarios data of RCP26, RCP45 and RCP85 scenarios released by CMIP5, and the land cover current data of Eurasia in 2010, the land cover scenarios of Eurasia were respectively simulated. The results show that most land cover types would generally have similar changing trends in the future, but with some difference in different periods under the three scenarios of RCP26, RCP45 and RCP85. Deciduous needleleaf forest, mixed forest, shrub land, wetlands and snow and ice would generally decrease in Eurasia during 2010–2100. Snow and ice would have the fastest decreasing rate that would decrease by 37.42% on average. Shrub land would have the slowest decreasing rate that would decrease by 5.65% on average. Water bodies would have the fastest increasing rate that would increase by 28.78% on average. Barren or sparsely vegetated land would have the slowest increasing rate that would increase by 0.76%. Moreover, the simulated results show that climate change would directly impact on land cover change in Eurasia.  相似文献   

Episodic gravitational collapse and migration of the mountain chain during orogenic roll‐on in the Himalayas     

T. H. BELL  J. SAPKOTA 《Journal of Metamorphic Geology》2012,30(7):651-666

An ～W–E belt of maximum bulk horizontal shortening (the orogen core) moved North relative to the overlying crust to form the Himalayan Syntaxes due to roll‐on of this portion of the Indian plate. This displacement occurred below a lengthy succession of gently dipping decollements that formed episodically at a depth of ～30 km along the orogen core due to numerous periods of gravitational collapse and spreading of the overlying ductile crust. Successively developed basal decollements were deformed when continued bulk horizontal shortening of the orogen core below reasserted dominance over the effects of gravitational collapse above causing refolding about steeply dipping axial planes. This resulted in northwards migration of the orogen core above depths of ～30 km causing rocks metamorphosing at depths of ～22 km on the north side of the orogen core to be moved to its south side with no change in depth as roll‐on progressed. Garnet porphyroblasts record this lengthy history of lateral migration across the orogen within their inclusion trails. The ～6.4 kbar average pressures accompanying it were obtained from the Mn, Fe and Ca contents of successive garnet cores. Garnet grew at depths of ～22 km until movement towards the surface initiated on successively developed decollements that accommodated the volume constraints of gravitational collapse and spreading on both sides of the orogen. The speed of extrusional displacement increased the further the rocks migrated from the orogen core developing mylonitic schists around the porphyroblasts. This truncated inclusion trails against all matrix foliations as the porphyroblasts were carried towards the surface. Indeed, these rocks were multiply deformed during at least four distinct periods of deformation after mylonitization began and prior to exposure above the Main Central Thrust (MCT). Three or more sub‐vertical and sub‐horizontal foliations were formed during each of the five changes in FIA trend (foliation inflection/intersection axes in porphyroblasts) preserved in these rocks. The inclusion trail asymmetries and P‐T of garnet core growth accompanying each FIA reveal that the first four changes in FIA trend, which define periods of tectonism about one direction of horizontal bulk shortening (relative plate motion), occurred on the north side of the orogen core. The fifth occurred on the south side of the orogen core and the switch in shear sense on gently dipping foliation planes that resulted from this shift to the south eventually led to the development of the MCT. When magnetic anomaly 22 that formed in the Southern Indian Ocean Ridge is taken into account, these five changes in FIA trend correlate markedly with changes in the motion of India relative to a constant Eurasia from 50 to c. 25 Ma. They reveal that Eurasia moved NNW during FIAs 1, 3 and 4 and SSE during FIA 5 when the shear sense on gently dipping foliations switched to top to the S. They suggest collision of India with Eurasia took place at 50 Ma, immediately prior to the development of FIA 1.  相似文献   

1949—2009年欧亚大陆强冷空气活动频次的变化特征     

王宗明  孙照渤  李忠贤  倪东鸿 《气象与减灾研究》2011,34(1):16-23

利用NCEP/NCAR提供的1949—2009年sig995层逐日平均温度资料,分析了近60 a欧亚大陆强冷空气活动频次年际变化的地区差异,并讨论了强冷空气活动的区域特征以及各区域强冷空气活动的变化特征。结果表明:欧亚大陆强冷空气活动可分为34个变化区,按照年代际变化及地理位置相邻可进一步归纳为9类地区。9类地区的强冷空气活动年频次存在共同变化特征,例如在20世纪60年代末至80年代中期普遍偏少;但也存在差异,例如80年代中期至90年代初高纬度地区偏多,而较低纬度的中国以及周边地区偏少。值得注意的是,新地岛周边地区以及西伯利亚中、南部地区强冷空气活动频次始于20世纪90年代中期的下降趋势延续至今,近几年欧亚大陆多数地区强冷空气活动频次偏少。  相似文献   

欧亚大陆北部盆地发育历史——来自东西向跨洲剖面的证据   总被引：1，自引：0，他引：1       下载免费PDF全文

毛翔  李江海  傅臣建  程海艳  高危言 《地质科学》2011,(3):763-774

板块演化控制了盆地的形成与演化,盆地的性质和地质特征由其所处的板块构造单元决定.本文从大地构造背景角度出发,沿北纬60°±5°绘制了欧亚大陆东西向跨洲剖面,西起北海内伊湖—阿兰盆地,东至北鄂霍茨克盆地,全长为11000km.剖面将构造单元划分为不同级别(超大陆与构造域—板块与造山带—陆块与构造带—盆地与拱起),进而将构...  相似文献   

欧亚北部2004年以来频繁冷冬的特征分析及机理初探   总被引：2，自引：0，他引：2  

乔少博  沈柏竹  王晓娟  封国林 《气象学报》2014,72(6):1143-1154

利用1961—2013年NCEP/NCAR发布的月平均全球再分析资料,分析了欧亚北部(40°65°N,50°-120°E)2004年以来频繁冷冬的异常特征及形成机理。结果表明:欧亚北部2004年以来冷冬频繁发生,但温度异常的空间分布,尤其中心冷区的位置有显著差异,主要表现为全区偏冷型(2005、2009、2010、2012年)和南部偏冷型(2004、2007、2011年)。全区偏冷年主要由北极涛动(AO)显著负位相所致,对应海表温度特征为北大西洋高、中、低纬度成东北-西南走向的"+、-、+"带状分布,该分布有利于北极涛动/北大西洋涛动(AO/NAO)负位相维持和增强;南部偏冷年大气内部活动异常为乌拉尔-贝加尔湖阻塞高压偏强,北极涛动/北大西洋涛动以弱正位相为主,对应主要海表温度特征为北大西洋中部偏高,其次则为太平洋年代际振荡(PDO)负位相下"类拉尼娜事件",上述海表温度异常均可促进类似欧亚遥相关的罗斯贝波列形成,有利于乌拉尔贝加尔湖阻塞高压偏强、亚洲中部多低槽活动。2004年以来欧亚北部两种类型冷冬的大气环流与海表温度均表现出与历史典型年相类似的特征。  相似文献   

Structural deformation and evolution of right-lateral strike-slip tectonics of the Liaohe western depression during the early Cenozoic     

《Journal of Asian Earth Sciences》2013

The Tan-Lu fault zone (TLFZ) traverses the Liaohe western depression (LHWD), affords an exceptional opportunity to reveal the structural deformation and evolution of a major strike-slip fault of the LHWD using three dimensional seismic data and well data. In this paper, based on structural interpretations of the 3-D seismic data of the LHWD, combined with depth slice and seismic coherency, a variety of structural features in relation to right-lateral strike-slip fault (the western branch of the Tan-Lu fault) have been revealed presence in the depression, such as thrust faults (Xinlongtai, Taian-Dawa, and Chenjia faults), structural wedges, positive flower structures, and en echelon normal faults. Fault cutoffs, growth strata and the Neogene unconformity developed in the LHWD verify that the activity of right-lateral strike-slip from the late Eocene to Neogene (ca. 43–23 Ma). The study indicates that the right-lateral strike-slip played an important role in controlling the structural deformation and evolution of the LHWD in the early Cenozoic. Moreover, the front structural wedge generated the gross morphology of the Xinlongtai anticline and developed the Lengdong faulted anticline during the late Eocene, and the back structural wedge refolded the Lengdong faulted anticline zone in the late Eocene to the early Oligocene. Wrench-related structures (the Chenjia thrust fault and the en echelon normal faults) were developed during the late Oligocene. Uniform subsidence in the Neogene to Quaternary. Furthermore, the driving force of the right-lateral strike-slip deformation was originated from N–S extension stress related to the opening of the Japan Sea and NE–SW compression, as the far-field effect of India–Eurasia convergence.  相似文献   

Cenozoic Eurasia is not a single rigid plate: Paleomagnetic evidence     

Jean-Pascal Cogné 《Comptes Rendus Geoscience》2013,345(11-12):419-426

The widely distributed Cenozoic paleomagnetic inclination anomaly in Asia is usually attributed to either a widespread error of magnetic field recording due to an inclination flattening mechanism in sediments, or to the persistence of an anomalous non-dipolar component of the geomagnetic field throughout the Tertiary. Based on an analysis of the Asian paleomagnetic database for Meso-Cenozoic times, we suggest that instead this puzzling anomaly results from an overlooked global plate tectonics cause where the wide so-called Eurasian plate would have suffered from previously undetected transpressive north–south relative movements between its western and eastern ends since the Cretaceous. These relative movements are most probably accommodated by a component of right-lateral shear movement distributed in the Tornquist–Tesseyre zone, and a localized left-lateral shear movement in the Ural Mountain chain during the Tertiary. Therefore, Eurasia was not the single rigid plate that Cenozoic plate reconstructions have accepted.  相似文献   

Crustal structure of the Madeira–Tore Rise, eastern North Atlantic—results of a DOBS wide-angle and normal incidence seismic experiment in the Josephine Seamount region     

C. Peirce  P. J. Barton 《Geophysical Journal International》1991,106(2):357-378

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