地磁场长期变化特征及机理分析

将地磁场的总变化分为三部分：偶极场自身变化，非偶极场自身变化及非偶极场磁斑区通过对核幔边界（CMB）层环形电流的调制来影响偶极场的变化. 本文利用国际地磁参考场模型IGRF）1900～2000计算分析了地球不同深度地磁场分布及长期变化特征，且讨论了变化的可能机制. 可以推论，地磁场西漂和倒转不仅是非偶极场引起，同时与偶极场有密切关系.     

电阻率测深在地电异常判定中的应用

塘沽台NS方向地电阻率观测值在观测极距缩短后出现大幅度上升变化，为了判断此变化的性质及其产生的可能原因，开展了多次恢复原极距的对比观测。并依据该台已有的电测深资料，对此变化进行了最佳拟合的理论反演计算。经比测及反、正演计算结果分析，认为该台NS方向大幅度的上升变化其主要原因与台站观测极距缩短有关，可能是随观测极距的缩短，受浅部电性结构层影响增大，而与深部电性结构无关，因而这一变化不具有震兆意义。     

苏联中亚地区地震试验场地电阻率和大地电场的观测现状

为了研究地电阻率和电场的变化与地震活动性之间的关系,近年来苏联在中亚地震预报试验场进行了实地测量和多方面的探讨,现将其观测结果介绍如下。 一、地电阻率的变化与地震活动性关系的观测结果 1.1偶极电测深 1983年,苏联科学院高温研究所电磁方法试验考察队在伏龙芝地震预报试验场用偶极测深法,采用AB=620m的供电极距,对地壳上部岩层电阻率的变化进行了研究。     

南极中山站极夜、极昼期间地磁场的日变化规律及特征

利用1991年南极中山站的地磁资料，分析研究了极夜（5，6，7月）及极昼（11，12月）期间地磁场的变化规律及特征．结果表明，极昼期间的S出现的双峰现象要比极夜期间的明显的多，S是叠加在S之上的极盖区地磁场静日变化；极夜期间的Sq,Sq和SD的变化幅度小于极昼期间的变化幅度，大约是极昼期的1／3，SD大约是极昼的3／4.这主要是由于极夜期间太阳的直射点在北半球，在南半球太阳的波辐射少；极昼期间太阳直射点在南半球，太阳的波辐射增大，致使空间电离层等效电流强度发生变化产生的．     

东亚磁异常及其对中国东北地区地磁场的影响

利用东亚及邻区４９个地磁台１９７０－１９７９年、Ｈ、Ｚ的实测年均值，逐年计算、缓制了蒙古异常的地磁非偶极场等值图，给出了蒙古异常非偶极场Ｚｎ分量的焦点位置和强度变化及其对中国东北地区地磁场的影响量级，计算表明蒙古异常的年变化是该区地磁场年变化的主要成份。     

南半球平流层极涡崩溃早晚年环流异常特征

极涡崩溃是平流层大气环流一个重要的变化过程,本文利用31年的再分析资料研究了南半球平流层极涡崩溃早晚年的异常特征.研究结果表明,南半球平流层极涡崩溃偏早年极涡崩溃前后平流层环流场异常表现为整层一致的变化,即都为正温度异常、正位势高度异常和负纬向风异常;而南半球平流层极涡崩溃偏晚年极涡崩溃前后平流层环流场异常的整层一致性的变化不典型,而在符号上与极涡崩溃偏早年的异常相反.与北半球平流层极涡崩溃前后环流异常相反明显不同,南半球平流层极涡崩溃偏早或偏晚年在极涡崩溃前后的环流异常保持相同的性质.进一步分析表明行星波活动在南极极涡的崩溃过程中起到了重要作用,极涡崩溃早年上传行星波比极涡崩溃晚年强,并且持续时间长.通过波流相互作用,行星波的异常使得极涡崩溃早年和晚年10月的平流层高纬地区分别为位势高度正异常和负异常,环流异常持续保持可能最终影响了南半球平流层极涡的崩溃时间.分析显示南半球极涡崩溃偏晚与La Niña事件之间可能存在一定的联系,但在极涡崩溃偏早年与赤道太平洋海表温度异常(SSTA)并无明显关系.     

北半球平流层极涡崩溃过程的动力诊断分析

极地气候变化研究, 特别是极地在气候变化中作用的研究, 现在已经成为国际重要的研究领域, 是2007~2008年开展的“国际气候年”的核心研究问题. 针对以前研究中北半球平流层极涡崩溃时间的分歧, 首先确定了北半球平流层极涡在春季的崩溃时间, 并分析了在平流层极涡崩溃过程中的环流演变和波动活动特征. 分析表明北半球平流层极涡的平均崩溃时间为4月10日左右, 极涡崩溃时间的年际变化比较大, 最早和最晚的崩溃时间跨度达到两个月. 长期趋势表明20世纪90年代以来极涡持续时间增长. 对极涡崩溃异常早年和异常晚年的合成分析显示极涡崩溃过程在早晚年有不同的特征. 极涡崩溃早年, 平流层极涡在3月中旬只有一次快速的衰减过程, 这次过程主要与对流层上传的行星尺度波动异常有关; 而极涡崩溃异常晚年一般有两次衰减过程, 第一次衰减为一次快速过程, 对应有异常的波动活动, 和平流层的爆发性增温有关. 第二次过程则是一次慢过程, 此次过程不伴随异常的波动活动, 主要是非绝热过程起作用. 进一步对极涡崩溃异常早晚年大气低层环流异常的研究表明, 极涡崩溃早晚年低层温度场和位势高度场的异常上有明显不同, 这表明平流层极涡的崩溃伴随有上下层的动力耦合过程.     

SKKS震相记录特征及其对极远震深度的测定

就穿透地球内核的SKKS震相的传播路径、走时以及随深度变化的特性进行了分析讨论。对银川台记录SKKS震相的特征和震相识别做了研究总结，同时给出了SKKS震相求极远震深度列线图。经过震例检验，用SKKS震相测得的深度在单台定位中相对比较准确，为应用SKKS震相测准极远震深度，提高银川单台月报质量，提供了有利工具。     

极区电离层对IMF Bz 4次快速转向的响应——EISCAT/ESR雷达观测

利用EISCAT VHF和EISCAT Svalbard(ESR)雷达观测数据,对2003年2月12日IMF Bz分量4次快速方向转换期间,极区电离层,尤其是极尖/极隙区的响应特征进行了分析研究.随着IMF Bz方向的多次快速变化,地面雷达观测到极尖/极隙区所在位置随着开放-闭合磁力线边界在纬度方向上来回移动.在此期间,极区电离层等离子体水平对流多次反向,表现出与IMF Bz分量强的负相关性.进一步分析表明:极区磁层-电离层系统在日侧对IMF极性变化的平均响应时间约为3 min.     

海洋可控源电磁法发射源姿态影响研究

海洋电磁理论是建立在水平发射偶极的基础上.然而,由于海底洋流作用海洋可控源发射偶极可能产生水平摆动、倾斜和水平旋转,造成测量数据与理想状态的水平电偶极子的电磁响应有较大的偏差.为了研究发射源姿态变化对场的影响,本文提出利用欧拉旋转将发射偶极由源坐标系转换到地球坐标系,进而分析发射源姿态变化造成海洋电磁观测数据的误差分布...     

Indexing the relationship between polar motion and water mass change in a giant river basin

Previous studies on the relationship between polar motion and water mass change have mainly concentrated on the excitation of polar motion via global terrestrial water storage changes(TWSC). In view of the uneven distribution of global terrestrial water storage, the relationship between regional water mass change and polar motion needs to be further explored owing to the lack of documented results. In addition, given the uncertainty in the estimation of TWSC, it is required to develop appropriate indices to describe water mass change from different perspectives. The Amazon River basin(referred to Amazon hereafter), containing the world's largest river, located at around the 90°W longitude, is selected as the study area. Water vapor flux, precipitation, runoff and TWSC are selected as the indices of water mass changes to reveal the relationship between polar motion and water mass change in this giant basin. The Mann-Kendall(M-K) method, the accumulated anomaly analysis method and the curvature method are used to identify the abrupt change points; the least squares method is used to estimate the trends,and the Fast Fourier Transform(FFT) and the Ensemble Empirical Mode Decomposition(EEMD) are used to perform a periodic analysis, for all the above indices. It is shown that, of all the indices from 1948 to 2011, water vapor flux is the most closely related index to polar motion. In detail, precipitation and water vapor flux contain beat periods of polar motion; water vapor flux,precipitation and polar motion have a common M-K test abrupt change point(occurring in ca. 1968) at the 0.05 significance level; water vapor flux has a similar accumulated anomaly curve with that of polar motion; and water vapor flux is more highly correlated with polar motion than most other indexes. It is found, just like global TWSC, the χ2 component of the excitation via water vapor flux and water storage change in the Amazon follows that of observed polar motion; χ1 does not follow. However, the pattern in the Amazon that the χ2 component of the excitation by water follows that of observed polar motion is at a more significant level than in global. Finally, the new index termed Location of Vapor-based Inter Tropical Convergence Zone(LVITCZ) we proposed to describe the annual mean latitudinal location of water mass change shows a more close and visual relationship between water mass change and polar motion than other chosen indices do.     

对流输运在TOI断裂形成等离子体云块中的作用研究

极盖等离子体云块是极区电离层常见特征之一,其形成演化过程是当前重要研究课题.光电离高密度等离子体在对流输送作用下从日侧穿过极隙,通过极盖到达夜侧,已成为共识.日侧磁场重联作用下的极区对流输运过程,在舌状等离子体结构（TOI）"断裂"形成极盖等离子体云块中发挥重要作用.利用极区全域GPS/TEC观测数据,结合SuperDARN雷达实测的对流速度,对等离子体云块形成过程进行案例研究,重点分析两种TOI断裂形成等离子体云块的发生机制.研究结果显示,等离子体对流输运过程在TOI断裂形成等离子体云块过程中发挥关键性作用,对流形态或局部对流速度矢量急剧变化都可能导致TOI结构不稳定,使TOI结构断裂形成等离子体云块.     

Variations in the polar cap area during intervals of substorm activity on 20–21 March 1990 deduced from AMIE convection patterns

The dynamic behaviour of the northern polar cap area is studied employing Northern Hemisphere electric potential patterns derived by the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure. The rate of change in area of the polar cap, which can be defined as the region of magnetospheric field lines open to the interplanetary magnetic field (IMF), has been calculated during two intervals when the IMF had an approximately constant southward component (1100- 2200 UT, 20 March 1990 and 1300–2100 UT, 21 March 1990). The estimates of the polar cap area are based on the approximation of the polar cap boundary by the flow reversal boundary. The change in the polar cap area is then compared to the predicted expansion rate based on a simple application of Faraday’s Law. Furthermore, timings of magnetospheric substorms are also related to changes in the polar cap area. Once the convection electric field reconfigures following a southward turning of the IMF, the growth rate of the observed polar cap boundary is consistent with that predicted by Faraday’s Law. A delay of typically 20 min to 50 min is observed between a substorm expansion phase onset and a reduction in the polar cap area. Such a delay is consistent with a synthesis between the near Earth neutral line and current disruption models of magnetospheric substorms in which the dipolarisation in the magnetotail may act as a trigger for reconnection. These delays may represent a propagation time between near geosynchronous orbit dipolarisation and subsequent reconnection further down tail. We estimate, from these delays, that the neutral X line occurs between \sim35R_E and \sim75R_E downstream in the tail.     

地球自转的天文地球动力学效应研究(Ⅰ)--引力位和重力的变化

详细讨论了地球自转的天文地球动力学效应，地极移动和日长变化导致地球引力位系数产生时变特性并引起重力的摄动，根据理论力学的基本概念，导出了由于地球自转变化引起的地球引力位系数变化、重力摄动、垂线偏差和地球形变的表达式，并定量地研究了极移和日长变化对测站重力观测值和地球形变的影响，建议在高精度的空间大地测量中要顾及到地球自转变化引起的一系列效应。     

极移振幅主要周期分量的时变特征

用JPL近年发布的地极坐标序列求得1893―1998年间极移的振幅序列，用最大熵谱分析方法求得了该资料序列包含的一些周期的参数，并利用小波变换方法分析讨论了其中的主要周期的变化.结果表明，极移振幅变化中存在着约6.5年和约40年的主要周期，且它们均具有一定程度的时变性.因此，在研究讨论极移与一些地球物理现象和自然灾害现象的关系时，应特别注意极移振幅中主要周期的时变特征.     

夏季亚洲极涡的长期变化对东亚环流和水汽收支的影响

主要分析了1951～2004年夏季亚洲极涡强度和面积的长期变化趋势及其对东亚夏季环流,水汽输送和降水量的影响,发现1951～2004年,夏季亚洲极涡表现出了明显的强度减弱,面积缩小的变化趋势,并以面积缩小更为显著,这正对应于北极涛动（AO）指数在该时段的显著升高.在这种北半球中高纬大尺度环流变化的影响下,东亚夏季高空西风急流在近54年显著南移,冷空气活动的南侵程度明显增强,从而造成低空偏北风显著增强而偏南风减弱.与此相应,近54年整个中国区域内低空纬向风速呈明显的减小趋势.总的来看,东亚夏季风环流发生了明显减弱.同时,流经中国的中纬度西风水汽输送在近54年也表现出一致减弱的趋势,而南风水汽输送大致以110°E为界,以东的夏季风区呈显著的减弱趋势而以西则有明显的增加趋势.这种水汽输送的变化影响了中国不同区域内水汽输送通量散度的改变,进而使得夏季降水量发生变化.分析表明,夏季亚洲极涡的面积和强度与东北、华北和西北东部的水汽输送通量散度和夏季降水呈正相关,而与长江中下游、华南、西南、青藏高原和西北西部呈显著负相关,夏季亚洲极涡在近几十年的面积缩小和强度减弱是中国夏季降水长期变化的一个可能原因.     

Polar Mohr diagram method and its application in calculating the shear displacements of general shear zones with volume loss--With the Sangshuyuanzi ductile shear zone as an example

The main problem,in determining the shear displacement of a general shear zone with volume change using the available formula,is that it is hard to know the initial angle between the planes (or lines) in the plane of shear.A planar deformation analysis of this kind of ductile shear zone is carried out with the polar Mohr diagram.If the volume change is induced by homogeneous contraction in the Z direction of the shear zone,there are sufficient conditions for constructing a polar Mohr diagram regardless of sequence of the simple shear and volume change.Therefore,the angle between a line and the shear direction before and after the deformation can be measured.Making use of these lines the shear strain and the volume change can be calculated and the shear displacement can be determined.     

Polar Mohr diagram method and its application in calculating the shear displacements of general shear zones with volume loss

The main problem, in determining the shear displacement of a general shear zone with volume change using the available formula, is that it is hard to know the initial angle between the planes (or lines) in the plane of shear. A planar deformation analysis of this kind of ductile shear zone is carried out with the polar Mohr diagram. If the volume change is induced by homogeneous contraction in the Z direction of the shear zone, there are sufficient conditions for constructing a polar Mohr diagram regardless of sequence of the simple shear and volume change. Therefore, the angle between a line and the shear direction before and after the deformation can be measured. Making use of these lines the shear strain and the volume change can be calculated and the shear displacement can be determined.     

Climatic changes on orbital and sub-orbital time scale recorded by the Guliya ice core in Tibetan Plateau

Based on ice core records in the Tibetan Plateau and Greenland, the features and possible causes of climatic changes on orbital and sub-orbital time scale were discussed. Orbital time scale climatic change recorded in ice core from the Tibetan Plateau is typically ahead of that from polar regions, which indicates that climatic change in the Tibetan Plateau might be earlier than polar regions. The solar radiation change is a major factor that dominates the climatic change on orbital time scale. However, climatic events on sub-orbital time scale occurred later in the Tibetan Plateau than in the Arctic Region, indicating a different mechanism. For example, the Younger Dryas and Heinrich events took place earlier in Greenland ice core record than in Guliya ice core record. It is reasonable to propose the hypothesis that these climatic events were affected possibly by the Laurentide Ice Sheet. Therefore, ice sheet is critically important to climatic change on sub-orbital time scale in some ice ages.