石羊河流域干旱气候对ENSO事件的响应及预测分析     

罗晓玲 《沙漠与绿洲气象(新疆气象)》2020,14(4):46-51

根据石羊河流域5个气象站1961—2018年的降水、气温、干旱实况资料,利用气候统计学方法分析ENSO事件对该区气候变化及干旱的影响。结果表明:厄尔尼诺事件会造成流域春季降水偏多,春、秋、冬季气温偏高,易出现暖冬;拉尼娜事件则春季降水偏少,秋季降水偏多,冬季气温偏低,易出现冷冬,中下游发生中度以上春旱、春末夏初旱和伏旱的概率较高。应用1968—2010年旬、月气象要素和大气环流特征量,采用最优子集回归方法,建立降水和干旱统计预测模式,然后结合ENSO事件,通过加权平均法构建集成预测概念模型。对模型进行检验,拟合率与准确率较高,已投入业务使用。  相似文献   

Permian radiolarians,chert and basalt from the Daxinshan Formation in Lancangjiang belt of southwestern Yunnan,China   总被引：2，自引：0，他引：2  

Qinglai?FengEmail author  Shangyue?Shen  Benpei?Liu  Dietrich?Helmcke  Xianggui?Qian  Weiming?Zhang 《中国科学D辑(英文版)》2002,45(1):63-71

The stratigraphical sequences composed of chert and basalt were found in the Daxinshan area of Simao and the Manbie area of Jinghong, southwestern Yunnan. The Middle Permian to ealiest Late Permian radiolarians, such as Follicucullus and Pseudoalbaillella, have been identified from the chert. The chert from the Manbie area of Jinghong is characterized by high SiO₂content (over 92%), large ratios of MnO/TiO₂ (2.15) and low ratios of Al/(Al+Fe+Mn) (≤0.1) and Ce/Ce*(0.4), which indicate that the chert was deposited in pelagic basin. The chert from the Daxinshan area of Simao, however, is characterized by low SiO₂ content, low ratios of MnO/TiO₂ (0.27) and high ratios of Al/(Al+Fe+Mn) (0.49) and Ce/Ce*(0.88), which imply that the chert was deposited in continental margin basin. The basalts from the both areas belong to tholeiite series, and the chemical compositions of their major, rare earth and trace elements show the characteristics of MORB. These results evidence that there are volcanic rocks and chert sequences representing pelagic basin and oceanic basin near continent. These sequences and the formerly reported island-arc volcanic rock sequences imply that the Daxinshan Formation in the Lancangjiang belt represents a sedimentary assemblage formed in active continental margin basin.  相似文献   

柴北缘的大地构造演化及其地质事件群   总被引：10，自引：0，他引：10  

辛后田  王惠初  周世军 《华北地质》2006,29(4):311-320

柴达木盆地北缘及邻区包括六个二级构造单元:中南祁连地块(宗务隆天山期裂陷槽)、欧龙布鲁克微陆块、柴北缘祁连期结合带、柴达木地块、东昆仑晚天山-印支期结合带(东昆北岩浆弧)和西秦岭结合带。其中柴北缘及邻区的大地构造演化,经历了前寒武纪基底成生与演化、祁连期洋-陆转化、天山-印支期板内变形和中新生代陆相盆地演化-高原隆升等四个阶段。本文在论述各个演化阶段的沉积事件、岩浆活动、变质作用、构造形迹和成矿作用等地质事件群的基础上,对柴北缘的变质基底、全球大地构造对比和显生宙花岗岩等重大基础地质问题进行了讨论。  相似文献   

铁岭市近45年气候变化特征分析   总被引：23，自引：1，他引：23  

刘敏  张耀存  周昕  张菁 《气象》2006,32(5):99-104

利用线性倾向率、滑动平均等方法，对铁岭市1960--2004年间4个气象观测站的月平均气温、降水量、平均最高气温、平均最低气温以及初终霜、无霜期、积温、透雨等资料进行分析，结果发现铁岭市近45年气候变化特点为温度呈上升、降水略减少的趋势，特别是近15年，气温增暖幅度加大，降水春夏两季减少明显；但各季增温幅度差异较大，对气候变暖贡献最大的是冬季，平均最低气温升温幅度明显高于平均最高气温，气温日较差变小；初霜拖后、终霜提前及无霜期延长，积温明显增多，透雨偏晚频率增大，极端气候事件出现的几率增大。  相似文献   

RELATION BETWEEN SUMMER TYPHOON FREQUENCY ANOMALIES IN WEST PACIFIC AND ENSO EVENTS AND THE ANOMALOUS ATMOSPHERIC CIRCULATION CHARACTERISTICS     

周学鸣  魏应植  吴陈锋 《热带气象学报(英文版)》2006,12(1):16-23

By using data of serially numbered typhoons in northwestern Pacific and NOAA OLR data and NCEP/NCAR reanalysis data of wind field, based on the statistics and study of the relationship between the calendar years with more (or fewer) summer typhoons and ENSO events, we compared the composites of OLR eigenvectors and tropical summer wind fields during El Nino and La Nina events with more or fewer than normal summer typhoons, respectively. The results show that, in summer, without remarkable systematic anomalies of Mascarene High and Australia High in South Hemisphere, the anomaly of Walker circulation will dominate and follow the rule of ENSO impacts to atmospheric circulation and typhoon frequency. Otherwise, when systematic anomalies of Australia High appear during the El Nino events, circulation anomalies in the South Hemisphere will dominate, and many more typhoons will occur. In 1999, which is a special year of La Nina events, northward and eastward monsoon was induced by the stronger Mascarene High, and fewer typhoons arose. The typhoon source are regions where weak vertical wind shear, warm pool in western Pacific and the area with monsoon troughs are overlapping with each other. Finally, this paper analyzes and compares the source locations and ranges of more (fewer) typhoons in the events of El Nino and La Nina, respectively.  相似文献   

Climate change and North Sea storm surge extremes: an ensemble study of storm surge extremes expected in a changed climate projected by four different regional climate models   总被引：5，自引：0，他引：5  

Katja Woth  Ralf Weisse  Hans von Storch 《Ocean Dynamics》2006,56(1):3-15

The coastal zones are facing the prospect of changing storm surge statistics due to anthropogenic climate change. In the present study, we examine these prospects for the North Sea based on numerical modelling. The main tool is the barotropic tide-surge model TRIMGEO (Tidal Residual and Intertidal Mudflat Model) to derive storm surge climate and extremes from atmospheric conditions. The analysis is carried out by using an ensemble of four 30-year atmospheric regional simulations under present-day and possible future-enhanced greenhouse gas conditions. The atmospheric regional simulations were prepared within the EU project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). The research strategy of PRUDENCE is to compare simulations of different regional models driven by the same global control and climate change simulations. These global conditions, representative for 1961–1990 and 2071–2100 were prepared by the Hadley Center based on the IPCC A2 SRES scenario. The results suggest that under future climatic conditions, storm surge extremes may increase along the North Sea coast towards the end of this century. Based on a comparison between the results of the different ensemble members as well as on the variability estimated from a high-resolution storm surge reconstruction of the recent decades it is found that this increase is significantly different from zero at the 95% confidence level for most of the North Sea coast. An exception represents the East coast of the UK which is not affected by this increase of storm surge extremes.  相似文献   

Seismic Moment Tensor Resolution on a Local Scale: Simulated Rockburst and Mine-induced Seismic Events in the Kopanang Gold Mine, South Africa   总被引：2，自引：0，他引：2  

Jan Šílený  Alexander Milev 《Pure and Applied Geophysics》2006,163(8):1495-1513

Seismic records contain information about the effect of the source as well as the effect of wave propagation through the rock mass. The effect of wave propagation is usually not well known as only simplified models of geological structures are available. Therefore, the information about the source retrieved by inverting seismograms may include errors due to incomplete knowledge of the rock mass along the propagation path, which in turn cause a distortion in the calculated moment tensor (MT). The distortion of the MT on a local scale was observed by inverting records of a simulated rockburst conducted at the Kopanang gold mine in South Africa. A dominant isotropic component of the explosive characteristics was found from the inversion. The deviatoric components retrieved from the blast are spurious. A test of their stability indicated that they are not significant, assuming an uncertainty above 5% for velocities and 10% for attenuation within the homogeneous model available for the mine. Thus, the retrieval of the MT from records of local networks in mines using a homogeneous model of the rock mass seems to be feasible. However, the homogeneous model of the rock mass can only be applied to close stations, within a few kilometers of the source. The seismic records from distant stations were too complex to be modelled by a homogeneous rock mass. Records of six mine-induced seismic events recorded at the Kopanang gold mine were also inverted. A vertical linear dipole along the pressure (P) axis was found for three of the events, suggesting a pillar burst. The mechanism of two events contains an isotropic implosion together with a nearly vertical dip-slip, and seems to indicate a combination of a cavity collapse with a down dip-slip along a nearly vertical fault. One event corresponds to a dipole along the tensional (T) axis. However, it is vertical, thus its association with tensile faulting of the hangingwall is uncertain.  相似文献   

High precision locations of LP events on Mt. Etna: Reconstruction of the fluid-filled volume     

S. Gambino 《Studia Geophysica et Geodaetica》2006,50(4):663-674

During 1991–93 at Mount Etna, long-period (LP) events occurring in swarms characterized the evolution of the eruption. The presence of multiplets i.e. groups of events with similar waveform signatures, has been recognized within this activity. Traditional techniques for locating LP events do not allow obtaining reliable hypocenters, which have only succeeded in placing earthquakes in a roughly 1 km² area slightly east of the Mt. Etna Northeast Crater. Hypocenters have been relocated in two steps: the absolute location has been improved using Thurber’s code and a complex 3D velocity model; a highly precise relative location has been applied on multiplets to define the source geometry. 3D locations and high precision analysis suggest that during the 1991–93 eruption the resonator producing LP events was a part of the uppermost Northeast Crater conduit, measuring 210 meters in height and 45–50 meters in diameter.  相似文献   

2004年3月18日高纬磁层顶多重通量管事件分析          下载免费PDF全文

魏勇  肖池阶  濮祖荫  洪明华  万卫星  刘振兴 《地球物理学报》2006,49(4):929-935

2004-03-18 23:10～23:50 UT期间，“双星（Double Star）”探测一号卫星（TC 1）在向阳面磁层顶高纬晨侧由内向外穿越磁层顶，其时TC_1的GSM坐标为 (75RE, -55RE, -54RE), RE为地球半径.穿越过程中TC_1观测到了8个通量管和1个磁通量传输事件（FTEs）.在此期间Cluster星簇位于向阳面太阳风内，其GSM坐标为(180RE, -31RE, -62RE)，其4颗卫星监测到行星际磁场（IMF）的BZ分量持续南向，BＹ有较大的负值.本文的研究表明：TC_1观测到的前7个通量管具有准周期重现性，周期大约是1～4 min，明显小于以前所观测到的FTEs的平均周期(8～11 min)；所有的通量管都具有较强的核心场.本文分别使用最小方差分析法（MVA）和Grad_Shafranov反演方法（GSR）对通量管的轴向进行了分析和对比，发现所有的通量管主轴基本沿晨昏向，结果显示GSR方法在轴向分析上比MVA优越.本文使用GSR方法对通量管的磁场结构进行了分析，恢复出了通量管的磁场在卫星穿越面的结构图；此外，本文还对这次多重通量管事件进行了deHoffmann Teller(HT)分析，结果表明，所有通量管大致朝南极方向运动，均来源于向日面低纬区域.这说明它们可能起源于向日面低纬区，由该区的磁场分量重联产生.  相似文献   

河西走廊地质历史中宋辽干冷期灾变事件及其影响          下载免费PDF全文

赫明林  曹兴山  曹炳媛 《甘肃地质》2006,15(1):10-18

宋辽寒冷干旱期的急剧降温,使河西地区降水量迅速减少,气候变得更为干旱。植被枯萎,风暴、沙暴、尘暴、火灾、旱灾、饥荒等灾害事件频繁发生,从而引发了一系列生态环境问题和战争动乱,对中国政治、社会、经济、文化产生重大影响。依据历史资料和考古研究成果及地质记录中“事件标志层”层位、年代,确定宋辽寒冷干旱期发生于公元1000~1050年,发展于公元1050~1100年,强盛于公元1100~1320年,消亡于公元1320~1335年。  相似文献