Quantification of both normal and right‐lateral late Quaternary activity along the Kongur Shan extensional system,Chinese Pamir          下载免费PDF全文

Marie‐Luce Chevalier  Jiawei Pan  Haibing Li  Dongliang Liu  Meng Wang 《地学学报》2015,27(5):379-391

The Kongur Shan Extensional System (KES) is a ~250 km long normal fault system that bounds the Muji–Tashkorgan basin of the Chinese Pamir. It accommodates E–W extension due to the northward indentation of the Pamir salient, and its late Miocene activity has been the focus of tectonic studies. While the KES has a main normal component, ~WNW–ESE‐striking segments have an additional right‐lateral strike‐slip component. Here, we quantify late Quaternary horizontal and vertical slip rates at three locations along the KES, where active faults cut and offset abandoned geomorphic features. We find rates of >3–4 mm a^?1 (horizontal) along the western Muji fault in the north and of ~1.7 mm a^?1 (vertical) and ~1 mm a^?1 (horizontal) along the Kongur Shan fault in the south during the late Pleistocene. These rates are consistent with GPS and late Miocene rates, and imply that E–W extension in the Muji–Tashkorgan basin is faster in the north than in the south.  相似文献   

人类活动排放的CO₂及气溶胶对20世纪70年代末中国东部夏季降水年代际转折的影响     

王欢  李栋梁 《气象学报》2019,77(2):327-345

全球变暖背景下,中国东部夏季降水在20世纪70年代末开始较19世纪呈现东北及长江中、下游地区多雨,华北及华南少雨的特征。与此同时,人类活动排放的CO₂及气溶胶量也发生了明显的年代际变化。文中利用地球系统耦合模式（CESM）诊断了中国东部夏季的水分收支对人类活动排放的CO₂及气溶胶年代际变化的响应。发现CO₂排放量增加后,江淮流域的水汽辐合以及中国南方的水汽辐散主要是与质量辐散有关的动力项及与湿度梯度相关的热力项共同作用的结果,但动力作用更显著。气溶胶效应则主要通过动力作用使得江淮流域水汽辐合,而中国南方地区水汽辐散。虽然CO₂和气溶胶对辐射量及温度的影响差别很大,但通过改变温度梯度,热成风效应产生的动力作用都会导致江淮流域上升运动增强,降水增多;而中国南方下沉运动显著,降水减少,与观测结果一致,且CO₂相较于气溶胶的影响更为显著,证实了20世纪70年代末人类活动对中国东部夏季降水年代际转折的影响。   相似文献   

气候变暖背景下西太平洋副热带高压体形态变异及热力原因     

孙圣杰  李栋梁 《气象学报》2019,77(1):100-110

采用美国NCEP/NCAR再分析资料,利用相关、合成分析、大气热源的计算等方法,研究了气候变暖背景下西太平洋副热带高压（副高）空间形态的变异及热力原因。结果表明,气候变暖前、后各层副高形态特征有很大的差异,副高体的空间形态从850—700 hPa开始显著西伸南扩,到500 hPa最为明显。各层副高在冷、暖期的形态差异与其周围大气热源和涡度的变化相对应。随着气候变暖,副高西侧和南侧的大气热源在850—700 hPa上开始有明显的加强,500 hPa热源加强最明显,且副高体南侧热源中心有所南移;同时,其西侧和南侧从对流层低层至中高层有反气旋涡度的增大,西侧的反气旋涡度在850—700 hPa增大最明显,南侧的反气旋涡度在500 hPa增大最明显,且反气旋中心整体南移。表明气候变暖后,副高体西侧和南侧大气热源的加强,导致相应区域反气旋涡度增大,副高体向反气旋涡度增大的方向发展,从而使副高西脊点西伸,南边界南扩,整体南移。   相似文献   

大陆构造变形与地震活动——以青藏高原为例   总被引：5，自引：0，他引：5  

李海兵  潘家伟  孙知明  司家亮  裴军令  刘栋梁  Marie-Luce CHEVALIER  王焕  卢海建  郑勇  李春锐 《地质学报》2021,95(1):194-213

大陆内部构造变形和地震活动往往突显出复杂的、区域性的特征,很难用板块构造理论来解释。青藏高原是大陆构造变形的典型实例,具有不同构造变形的分区特征,不仅表现在物质组成、地形地貌和断裂组合等方面的不同,而且还表现出不同的地震活动特征。东昆仑断裂带以北的青藏高原北部地块,主要发育一系列挤压环境下的盆岭构造,表现为以连续变形为特征的上地壳挤压缩短变形;高原中北部巴颜喀拉地块,具有整体向东运动的特点,变形主要集中在其边缘,表现为刚性块体运动特征。在东部,由于稳定的四川盆地(扬子地块)的阻挡,位于龙日坝和龙门山断裂带之间相对坚硬的龙门山地区受到东西向强烈挤压,西部边界为伸展变形;在高原中央腹地羌塘地块西部,由于上地壳物质在向东挤出的驱动下不断变形,沿一系列小型正断层和走滑断层以伸展变形为主,表现为弥散型变形特征。相比之下,羌塘地块的东部向东-南东方向挤出,在大型走滑断层之间形成一个刚性块体;高原南部地块以东西向伸展的南北向裂谷系为主要变形特征,高原南缘以南北向挤压的大型逆冲断裂系为特征。历史地震和仪器记录的大地震(M≥8)只发生在高原东北和东南部的大型走滑带,以及东部和南部边缘的大型逆冲断裂上,沿后者更为频发。到目前为止,高原其他地区只发生了8级以下地震。青藏高原这种分区域的地壳变形形式和地震活动分布是大陆构造变形的重要特征。  相似文献   

多波束测深系统声线跟踪方法对比分析          下载免费PDF全文

孙强  李明叁  王洪燕  张浩  李东亮 《海洋测绘》2015,(2):48-51

多波束测深系统的声学原理和海水的不均匀性,使得声波在传播过程中发生声线的折射现象,对波束测点位置的计算带来较大误差。针对多波束数据后处理常用的几种声线跟踪方法,通过模型分析,仿真实验,对比分析得出了各个方法的优缺点,估计了各种跟踪方法的模型精度,证明等效声速法与常梯度法应用价值较高。  相似文献   

Why does the IOD-ENSO teleconnection disappear in some decades?     

徐腾飞  袁东亮 《中国海洋湖沼学报》2015,33(2):534-544

Lag correlations between sea surface temperature anomalies(SSTA) in the southeastern tropical Indian Ocean(STIO) in fall and Nio 3.4 SSTA in the eastern equatorial Pacific in the following fall are subjected to decadal variation,with positive correlations during some decades and negative correlations during others. Negative correlations are smaller and of shorter duration than positive correlations. Variations in lag correlations suggest that the use of the Indian Ocean Dipole(IOD) as a predictor of the El Nio Southern Oscillation(ENSO) at a lead time of one year is not effective during some decades. In this study,lag correlations between IOD and ENSO anomalies were analyzed to investigate why the IOD-ENSO teleconnection disappears during decades with negative correlations. Anomalies induced by the IOD in the equatorial Pacific Ocean during decades with negative correlations are still present,but at a greater depth than in decades with positive correlations,resulting in a lack of response to oceanic channel dynamics in the cold tongue SSTA. Lag correlations between oceanic anomalies in the west Pacific warm pool in fall and the equatorial Pacific cold tongue with a one-year time lag are significantly positive during decades with negative correlations. These results suggest that oceanic channel dynamics are overwhelmed by oceanatmosphere coupling over the equatorial Pacific Ocean during decades with negative correlations. Therefore,the Indonesian throughflow is not effective as a link between IOD signals and the equatorial Pacific ENSO.  相似文献   

Mapping the permafrost stability on the Tibetan Plateau for 2005–2015     

Youhua RAN  Xin LI  Guodong CHENG  Zhuotong NAN  Jinxing CHE  Yu SHENG  Qingbai WU  Huijun JIN  Dongliang LUO  Zhiguang TANG  Xiaobo WU 《中国科学:地球科学(英文版)》2021,64(1):62-79

Data scarcity is a major obstacle for high-resolution mapping of permafrost on the Tibetan Plateau(TP).This study produces a new permafrost stability distribution map for the 2010 s(2005–2015)derived from the predicted mean annual ground temperature(MAGT)at a depth of zero annual amplitude(10–25 m)by integrating remotely sensed freezing degree-days and thawing degree-days,snow cover days,leaf area index,soil bulk density,high-accuracy soil moisture data,and in situ MAGT measurements from 237 boreholes on the TP by using an ensemble learning method that employs a support vector regression model based on distance-blocked resampled training data with 200 repetitions.Validation of the new permafrost map indicates that it is probably the most accurate of all currently available maps.This map shows that the total area of permafrost on the TP,excluding glaciers and lakes,is approximately 115.02(105.47–129.59)×10^4 km^2.The areas corresponding to the very stable,stable,semi-stable,transitional,and unstable types are 0.86×10^4,9.62×10^4,38.45×10^4,42.29×10^4,and 23.80×10^4 km^2,respectively.This new map is of fundamental importance for engineering planning and design,ecosystem management,and evaluation of the permafrost change in the future on the TP as a baseline.  相似文献   

河网多尺度Morphing的变换方法研究     

彭东亮  邓敏  赵彬彬 《遥感学报》2012,16(5):953-968

本文基于Morphing连续变形技术的一种技术探讨河网的多尺度变换方法,主要涉及对应河流间的Morphing变换和无对应河流的河流删除这两类问题。本文首先对两个不同比例尺的对应河网进行河流匹配,确定河流的对应情况,然后以较大比例尺河网向较小比例尺河网变化的方式进行河网的多尺度变换。对于在两个不同比例尺河网中对应存在的河流,采用顾及交汇点信息及河流结构信息的形状内插方法进行Morphing变换;对于仅在较大比例尺河网中存在而在较小比例尺河网中不存在的河流,则以河流的干支总长作为其重要性标准,进而依据给定的变换程度参数删除重要性较小的河流。最后,通过实验分析与对比,验证了本文方法能够有效改善河流间的Morphing变换效果,提高河流选取的准确性。  相似文献   

中国干旱气候分区及其降水量变化特征   总被引：20，自引：5，他引：15  

杨绚  李栋梁 《干旱气象》2008,26(2):17-24

利用中国614个气象台站1974～2006年历年月平均降水资料,计算各站的降水量距平百分率及其干旱等级序列,采用REOF等方法,对干旱等级序列进行气候分区,并分析各区域50a左右干旱等级的时间演变特征。结果表明：全国降水量具有显著的年代际变化特征,尤其西北地区年代际变化十分突出,其中新疆西部地区在21世纪以来降水量的增加非常明显,增加的程度也是近33a中最强的。根据干旱等级序列的旋转载荷向量将中国划分为11个区域,它们各自具有不同的旱涝特征。干旱等级序列和代表站资料反映出近50a东北、华北及河套地区的干旱明显加重,而西北大部分地区降水量有显著的增加。  相似文献   

Impact of Different Guidances on Sensitive Areas of Targeting Observations Based on the CNOP Method   总被引：1，自引：0，他引：1       下载免费PDF全文

TAN Xiaowei  WANG Bin  WANG Dongliang 《Acta Meteorologica Sinica》2010,24(1):17-30

The conditional nonlinear optimal perturbations(CNOPs) obtained by a fast algorithm are applied to determining the sensitive area for the targeting observation of Typhoon Matsa in 2005 using an operational regional prediction model-the Global/Regional Assimilation and PrEdiction System(GRAPES).Through a series of sensitivity experiments,several issues on targeting strategy design are discussed,including the effectivity of different guidances to determine the sensitive area(or targeting area) and the impa...  相似文献