江淮梅雨对东亚副热带夏季风进程及海温异常的响应

利用1960—2020年江淮地区75个气象站逐日降水量、气温、相对湿度资料以及NCEP/NCAR再分析资料和Hadley中心海表温度资料，研究了东亚副热带夏季风进程变异对江淮梅雨的影响，揭示了不同类型梅雨期太平洋海温及大气环流异常特征。结果表明：8种江淮梅雨类型中，多雨型占45.9%，少雨型占54.1%，其中多雨型在前30 a占36.7%，后31 a占63.3%。江淮典型梅雨年（高温高湿多雨）的主要特征为安徽南部、江苏中部及湖北东部地区降水偏多，安徽南部、江西东北部及浙江西北部气温偏高，淮河流域湿度大；而在非典型梅雨年（低温低湿少雨）大部分地区雨量偏少，气温呈"东高西低"分布，低温中心区位于淮河中游，湿度呈"西大东小"分布。欧亚大陆中高纬度阻塞高压增强，脊前向南输送的西北气流加强且路径偏东，中国东北冷涡强度较强且位置偏西南，东亚大槽加深，槽后冷空气向南输送，有利于典型梅雨形成。当前期冬春季赤道东太平洋海温异常偏高，西太平洋海温异常偏低时，西太平洋副热带高压强度偏强、面积偏大、脊线位置偏南、西伸脊点偏西，东亚副热带夏季风推进到江淮地区的时间偏早，出梅偏晚，梅雨期降水量偏多。     

Linear study on landscape heterogeneity of Dongling District of Shenyang

Landscape configuration means the distribution and conjunction of landscape element. Inflenced by geomorphological process and human interference, the landscape configuration of Dongling District of Shenyang City appears 5 types: even distribution, aggregated distribution, linear distribution, positive interrelation spatial linkage, and negetive interrelation linkage. We subdivided two lines, which go through the landscape of Dongling District separately, into segments of equal length and studied the information of the landscape elements, which is distributed on the line, by mathematical theory of communication. Then we expounded the characteristics of landscape heterogeneity and its changing law in Dongling District as well as the relationship with geomorphic condition and human disturbance.     

Bathymetric inversion of South China Sea from satellite altimetry data

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中强震前形变固体潮汐资料短期信息的提取

分析了各种潮汐观测资料处理方法,针对短期异常提取的要求,提出了适合提取短期异常信息的潮汐资料处理方法,对其计算公式进一步推导和展开。应用这些方法对华北地区和西南地区的重力、倾斜、应变等形变观测量进行了计算。对地震前潮汐因子、时间滞后、响应比等潮汐参数的异常信息进行了提取与分析;突出了震源区附近的短期异常信息,并分析总结其变化特征。     

云南水汞在打破M≥5级地震平静后强震前的异常分析

通过普洱6．3、宁蒗6．2级和姚安6．5级3个在省内M≥5级地震平静了10余个月,打破5级平静后发生的M≥6级强震前水汞的异常分析,并着重短临异常研究,结果表明这3次地震前水汞均有中期和短、临异常,中、短、临异常台站数为两头少,中间多。中期异常表现为11％。22％的水汞观测台站震前出现2—10个月的中期异常;短期异常表现为震前2—3个月,平均44％的台站观测到短期异常,最大异常幅度与异常判定线比值在1．3—3．2倍之间：强震前都只有1个台站出现临震异常。短期异常有差异,宁蒗6．2级主震前,短期异常在2次前震前出现,普洱6．3、姚安6．5级地震前,水汞短期异常在打破5级平静的地震前出现,水汞短期异常有活跃、平静的现象。最早出现中期异常的台站相对靠近震中。     

<Emphasis Type="Italic">In-situ</Emphasis> trace element analyses and Pb-Pb dating of zircons in granulite from Huangtuling,Dabieshan by LAM-ICP-MS

It is revealed by CL images that there are multi-stage growth internal structures of zircons in the Huangtuling granulite, including the inherited zircons, protolith zircons, sector and planar zone zircons and retrograde zircons. In-situ trace element compositions and Pb-Pb ages have been analyzed by LAM-ICP-MS. The sector and the planar zone domains show typical trace element characteristics of granulite zircon (low Th, U, Th/U, total REEs, clear negative Eu anomalies, relatively depleted HREE and small differential degree between MREE and HREE, etc.), indicating that they formed during granulite-facies metamorphism. The protolith zircons have trace element characteristics of crustal zircon (high Th, U, Th/U, total REEs and enriched HREEs, etc.). 12 analyzed spots on granulite-facies domains give a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of (2154±26) Ma (MSWD = 3.8), which is the best estimated age of granulite-facies metamorphism of this sample. The weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 5 analyzed spots on protolith zircon domains is (2714 ± 22) Ma (MSWD = 1.4), which represents the protolith forming time. The discovery of ca. 3.4 Ga inherited zircon indicates that there are Palaeoarchean continental materials in this area. The interpretation of formation conditions and the ages of zircons can be constrained by simultaneous in-situ analysis of trace elements and ages.     

Sea surface height and transport stream function of the South China Sea from a variable-grid global ocean circulation model

The study on the South China Sea (SCS) circulation has a history of more than 40 years. Nevertheless, the SCS circulation is not fully understood compared with the Bohai Sea, Yellow Sea and East China Sea (ECS). Many numerical studies on the SCS circulati…     

Implementation of configuration dependent stiffness proportional damping for the dynamics of rigid multi-block systems

The distinct element method (DEM) has been used successfully for the dynamic analysis of rigid block systems. One of many difficulties associated with DEM is modeling of damping. In this paper, new procedures are proposed for the damping modeling and its numerical implementation in distinct element analysis of rigid multi-block systems. The stiffness proportional damping is constructed for the prescribed damping ratio, based on the non-zero fundamental frequency effective during the time interval while the boundary conditions remain essentially constant. At this time interval, the fundamental frequency can be estimated without complete eigenvalue analysis. The damping coefficients will vary while the damping ratio remains the same throughout the entire analysis. A new numerical procedure is developed to prevent unnecessary energy loss that can occur during the separation phases. These procedures were implemented in the development of the distinct element method for the dynamic analyses of piled multi-block systems. The analysis results for the single-block and two-block systems were in a good agreement with the analytic predictions. Applications to the seismic analyses of piled fourblock systems revealed that the new procedures can make a significant difference and may lead to much-improved results.     

大别山地震波速度剖面的重力拟合及花岗岩带

笔者对穿越大别山造山带的六安—大冶宽角反射地震剖面进行了重力拟合。拟合结果表明严格按宽角反射地震速度换算成的密度剖面所产生的是一个重力高,它反映出大别山是一个穹隆,与实测大别山重力低大相径庭。只有将位于大别山山根上,南北大别之间设置一个从地表直达莫霍界面的巨大低密度体,重力曲线才能得到很好的拟合。这个低密度体应为近北西走向的花岗岩带。它与反射地震剖面上石镇透明反射地震带位置吻合,但宽度远较反射地震透明带为大。重力曲线的拟合进一步说明,在华北陆块与扬子陆块碰撞后的白垩纪时,大别山出现一个伸展期,在这个时期,大别山穹隆形成,并伴随有大规模花岗岩的侵入,超高压变质岩从地壳中下部折返到地表。研究说明,联合应用反射地震、宽角反射地震和重力,进行综合解释是必要的,可以得到更令人信服的地质结论。     

水平荷载作用下群桩相互作用的弹塑性数值分析

本文利用三维弹塑性有限元法对水平荷载作用下群桩基础特性进行了分析,讨论了群桩基础水平荷载作用下的承载性状和破坏机理,并探讨了桩距、桩数、桩长、桩径和土质各种因素对群桩效应的影响,指出桩距和桩数是影响群桩效应的主要因素。