极区电离层与磁层-电离层耦合

本文利用欧洲空间局设在北极区的非相干散射雷达系统EISCAT的观测资料讨论磁层-电离层耦合。磁静日和磁暴期间的观测样本比较表明,磁层基本过程对极区电离层有重要影响。这不仅说明极区电离层可看作这些过程的“全景屏幕”,也表明在南、北极区(特别是磁共轭点)进行同时观测的重要意义。文中还对进一步的南极研究课题提出了一些建议。     

THE INFLUENCE OF THE COSMIC RAY FORBUSH DECREASE ON THE LOW IONOSPHERE IN THE POLAR REGION

Used the ionization theory of the cosmic ray charged particles in the polar ionosphere, the influence of the cosmic ray Forbush decrease on the low ionosphere in the polar region is studied in this paper. The relationship between the Forbush decrease and the cosmic noise absorption during the polar night is analysed based on the data recorded by a Riometer at Antarctic Zhongshan Station (69° 22′24″S, 76°22′40″E). The relation of between the cosmic ray Forbush decrease and the cosmic noise absorption is well interpreted by means of the ionizaiotn theory.     

不同行星际磁场条件下极向运动极光结构的多手段联合观测

本文利用北极黄河站三波段全天空成像仪（ASI）的高分辨率的地面极光观测数据,联合欧洲非相干散射雷达（EISCAT）Svalbard雷达（ESR）,超级双子极光雷达网（SuperDARN）雷达等观测,研究了发生在2003年12月22日0900-1010 UT时间段内极区电离层极光和等离子体的变化特征。研究发现在不同行星际磁场（IMF）条件下,黄河站极光ASI均观测到了一系列极向运动极光结构（PMAFs）,其特征为极光在赤道向一侧点亮后向高纬扩展。这些PMAFs都伴随有明显的粒子沉降特征,且在IMF北向时该粒子沉降能达到更低的电离层E层区域,而此时这些PMAFs相应位置的高纬电离层出现了一个典型反向对流涡,这是高纬（尾瓣）重联的典型特征之一。这些结果表明北向IMF条件下的这些PMAFs是由高纬重联所产生。在IMF南向时,黄河站观测到的PMAFs可跨越更广的地磁纬度,表明其演化时间亦较长,其相应区域的电离层特征也表明该PMAFs由日侧磁层顶低纬磁重联所产生。     

南极中山站的f_0F2特征

本文利用电离层数字测高仪 (DPS - 4)所测的f0 F2和从美国NOAA和DMSP卫星观测估算的半球功率指数和午夜极光区赤道侧边界纬度等资料 ,考察中山站电离层的极区特征。结果表明 ,冬季中山站电离层内的电离生成主要取决于从磁层沉降的粒子。在太阳活动和地磁变化宁静环境下 ,磁正午极隙区内的软粒子是最主要的电离源 ,它能使f0 F2达全天的最大值 ;上、下午各有数小时处于极光带内时 ,高能粒子的电离作用也很重要 ;夜间进入极盖区后 ,电子密度则很低。夏季太阳辐射电离效应使f0 F2值比冬季增加 1- 1 .5MHz,而其日变化的最大值时间也提前了 1- 2hr。发生很大扰动时 ,极隙区和极光带的位置均向低纬方向移动。若中山站日间也处于极盖区内时 ,电子密度会大幅度下降 ,并常接收不到电离层回波的信号。在中等扰动环境下情况更加复杂。由于高纬电离层对流速度很高 ,离子 /中性分子间的碰撞复合系数就很大。热层中性大气全球经向环流对高纬电离层电子密度的增加无显著作用。磁暴期间中午从极隙区向南的等离子体对流对中山站f0 F2的增高也无明显影响。     

A comprehensive model current system for high-latitude magnetic activity - I. The steady state system

Summary. Magnetic variations at high latitudes represent the combination of magnetic perturbations from several different current systems. The relative effects of each of the contributory current systems vary from event to event, resulting in changes in magnetic perturbation patterns in a given local time sector which are a function of several variables, e.g. level of magnetospheric activity, spectrum of precipitating particles responsible for ionospheric conductivity, configuration of interplanetary magnetic field, etc. In this paper we extend the work of Hughes & Rostoker in which the steady state perturbation pattern in each local time sector was established from ground-based meridian line magnetometer data. We shall define the various current systems which contribute to the high-latitude magnetic perturbation pattern and we shall construct the model composite current system which best explains the high-latitude observations in the winter months. We shall discuss changes in this pattern as a function of season and as a function of the configuration of the interplanetary magnetic field. Finally, we shall relate the geometrical configuration of the ionosphere—magnetosphere current flow to the convection of plasma in the magnetosphere.     

南极普里兹湾船载地磁三分量数据处理分析

船载地磁三分量测量仪(STCM)具有易携带、无时空限制、多参数测量等特点,在极地恶劣环境下,显然比拖曳磁力仪更具优势。对第29次南极科学考察获得的船载地磁三分量数据进行船磁干扰场的校正分离,获得相应的三分量数据以及总场。校正后地磁三分量数据与拖曳磁力数据进行对比,其标准差为47.56 n T,表明其在极区内工作性能良好,数据质量可靠。计算结果为我国首次在极区海域内获得的地磁三分量磁异常,有关的技术流程方法将为今后中国极地科考实施船载地磁三分量测量提供有效的技术支持。     

Observations of geomagnetic pulsations and variations with a new borehole magnetometer down to depths of 3000 m

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A triaxial magnetometer has been developed for investigating the in situ skin effect of horizontal geomagnetic pulsations and variations in deep boreholes. The observations were carried out in the pilot borehole of the Continental Deep Drilling Program of Germany (KTB) down to depths of 3000 m and up to temperature of 90 C. A weak skin effect, due to the known very low conductivity of the penetrated crystalline rocks, of 90 to 95 per cent in amplitude and -5 to -10 rotation in phase has been observed at periods of 10 s and magnetometer depth of 2400 m.
An essential prerequisite for all calculations is the accurate determination of the orientation of the downhole magnetometer. It is demonstrated how oriented record samples of temporal variations at depth correlate precisely with those from the surface.
Results from surface magnetotelluric (MT) investigations show strong local distortions of the telluric field. The distortion of the MT tensor response has been determined by means of newly introduced skin-effect transfer functions, which are assumed to be undistorted.     

基于卷积神经网络的极光图像分类

极光是由带电粒子经磁层—电离层碰撞大气而产生的。面对形态各异、演变过程复杂的极光图像,对其合理分类为进一步探究日地电磁活动和能量耦合等空间物理问题奠定了基础。针对该问题,引入深度学习的方法,通过卷积神经网络模型自主表征极光特征并实现极光图像分类。该方法对2003年北极黄河站越冬观测的38 044幅和8 001幅典型极光图像分类正确率达93.17%和91.5%;自动识别2004—2009年观测数据的极光形态,4类极光时间分布规律与三波段激发谱能量分布基本一致。实验结果表明,基于卷积神经网络的极光表征方法,能有效实现极光图像的自动分类。     

尘卷风结构特征及其电场数值模拟研究

尘卷风是地球上常见的小型风沙灾害输移系统,但在火星上却大的多。而且尘卷风内部的电场对火星探测器产生严重的电磁干扰。通过建立尘卷风及其电场形成的模型,对尘卷风结构特征及电场进行数值计算。研究表明：尘卷风的形成机理可以用热对流泡理论来解释。沙粒在尘卷风中出现分层现象,粒径小的沙尘往往在粒径大的沙尘上面。尘卷风中带正负电荷的沙粒大约各占23.4%,荷质比大约为60 μC·kg^-1时,尘卷风数值模拟结果与野外观测值吻合。在尘卷风发展过程中,尘卷风电场大约需要60 s达到稳定。而且电场关于尘卷风中心基本对称,并且在尘卷风中心电场强度较大,在离尘卷风较远的地方,电场趋于零。在距离尘卷风中心一定距离处电场随高度增大先增大后减小,大约10 m以下电场随高度增大而增大,在10 m以上电场随高度增大而减小。     

极尖纬度午后极光嘶声的极大发生率

极尖纬度午后区是一个异常等离子体过程区，已发现该区在低地磁扰动条件下，多种空间物理现象活动强度极大（相对邻区）：强的向上场向电流，向下低能电子流极大，向上离子通量极大，Ｆ层电子密度极大等等。导致该区异常的根本原因尚不清楚。本文利用南极点站（磁纬约７５°）的极光嘶声的电场强度进行统计分析，发现该区３１－３８ｋＨｚ波段极光嘶声的发生率极大。本文还分析了该区极光嘶声发生率与地磁活动指数Ａｐ的关系，结果表明，它们之间有明显的相关关系。     

Laboratory studies of depositional DRM

Summary. Acquisition of magnetic remanence in slurries of fme grained organic muds settling in long tubes is investigated using a cryogenic magnetometer. The average settling behaviour of remanence carrying grains relative to the whole sediment gives information about the relative magnetic grain size spectrum, whereas the response of settled deposits to vibration gives an indication of the degree of alignment of particles and their average shape.
Two classes of behaviour are apparent in both the time and field dependence of detrital remanent magnetization (DRM) acquisition. Dilute slurries settling in the Earth's field (analogous to detrital sedimentation) acquire a remanence which reaches a maximum after about 2 day, whereas for concentrated slurries (analogous to slumped or bioturbated sediments) this takes only a matter of minutes. The field dependence of DRM in dilute slurries is in plausible quantitative agreement with Stacey's extension of the classical Langevin expression for the susceptibility of a paramagnetic gas, whereas concentrated slurries show a quasi-linear dependence of DRM on the applied field. Inclination errors are generally absent, but do appear in fields less than about 0.5 Oe, and when the magnetic fraction settles out preferentially. A weak negative dependence of DRM on temperature is found, but the results are too crude to provide a further test of Stacey's theory.
Remanence acquisition in slurries settled in zero field indicates that short term post-depositional magnetization processes are relatively unimportant in slurries that have ceased to compact rapidly. A large increase in remanence from naturally occurring sediments to slowly redeposited long cores, to rapidly settled slurries is best explained as a feature of compaction.     

2000年7月重大太阳事件的极隙区纬度观测研究

20 0 0年 7月 ,太阳表面发生了一系列的耀斑与日冕物质抛射事件 ,最大耀斑能级达X5 .7/3 B。地球表面发生相应特大磁暴 ,Dst指数最大负偏达 - 3 0 0 n T。中国南极中山站地处极隙区纬度 ,白天位于磁层极隙区 ,夜间位于极盖区 ,以多种高空大气物理观测设备详细记录了该磁暴过程。对有关数据的分析表明 ,高能粒子引起电离层吸收急剧增加 ,测高仪数据两天多信号空白 ,宇宙噪声吸收显著增加 ;地磁 Pc3 /5脉动增加与行星际磁场南向分量密切对应 ,显示行星际磁流体波对激发磁层脉动的贡献 ;磁暴主相期间 ,Pc3 /5脉动大幅度增加 ;极区地磁水平分量随南向行星际磁场变化 ,但滞后近 8小时 ;Dst指数与南向行星际磁场密切相关 ,磁暴受控于高度负偏的南向行星际磁场     

An automated superconducting magnetometer and demagnetizing system

Summary. A novel 3-axis superconducting magnetometer has been constructed using just one SQUID (Superconducting Quantum Interference Device) sensor. The magnetometer has been placed in a large mu-metal shield together with a non-magnetic oven and 3-axis af demagnetizer. Once a sample is entered into the system a microprocessor controller executes a predetermined measuring and demagnetizing/remagnetizing sequence. The system was originally designed automatically to determine field magnitude values from ceramics and igneous rocks but has proved itself to be a useful general purpose palaeomagnetic instrument.     

极区顶部电离层离子上行-DMSP卫星观测

本文利用DMSP卫星离子漂移速度测量数据,对高纬顶部电离层离子整体上行进行研究,主要考察平静时和磁暴期间离子上行强度与发生率随MLT(晨昏两侧)分布规律的变化;以及磁暴期间强的离子上行与等离子体对流及其剪切之间的关系。研究发现,磁暴期间强上行事件的发生率比平静期高近2倍,发生率的晨昏不对称性出现逆转,由平静时昏侧发生率较大变为磁暴期间晨侧发生率较大;磁暴期间晨侧离子上行速度的分布向速度高端加权,平均速度大于昏侧,最大上行速度远大于昏侧;强的离子上行往往与强对流剪切或强对流本身相伴随。     

Study and observation of the great solar event in July 2000 at cusp latitude

A series of solar flare and coronal mass ejection (CME) event occurred in July 2000, particularly the largest flare (X5.7/3B) with CME on 14th of July since 1989, which stimulated a great geomagnetic storm with D st index reaching -300 nT. A number of data have been obtained from the Chinese Antarctic Zhongshan Station (ZHS, INT Lat. 74.5°, L≈14), which is located at cusp latitude, and from the ACE satellite. After analyzing these data we have got the results as follows: a lot of solar high energy particles penetrated into the polar ionosphere and ionized it, which significantly increased the cosmic noise absorption (CNA) and blanked the DPS-4 data for more than two days. The magnetic pulsation in Pc 3/5 frequency band on the ground has a high relation with the fluctuation of interplanetary magnetic field (IMF) B z, which shows the contribution of interplanetary magnetohydrodynamical (MHD) waves to the Pc 3/5 pulsation on the ground. The Pc 3/5 pulsation was intensified much during the great magnetic storm. The H component of the magnetic field at ZHS varied with the southern value of IMF B z but lagged behind for about 8 10 h. While D st index responded to the variation of the IMF B z very quickly, which suggested that the magnetic storm occurred at low latitude firstly and then effected the ionospheric current at high latitude.     

等离子体片离子分界线的模拟研究

等离子体片离子向内磁层的渗透在亚暴和磁暴过程中都起到了重要作用.以往对于等离子体片离子向内磁层的渗透都是通过固定磁矩的磁层离子漂移轨道理论来进行的.本文将过去的(U,B)空间中固定磁矩的磁层离子漂移轨道理论扩展为固定能量的磁层离子漂移轨道理论,讨论了等离子体片质子在向地球输运过程中,不同能量的质子开放轨道和封闭轨道的分界线的特性,及其随Kp指数的变化.在高能端,随着能量的升高,等离子体片质子分界线地心距离逐渐增大,且分界线的晨侧地心距离远远大于昏侧的地心距离.在低能端,随着质子能量的降低,质子分界线地心距离逐渐增大,且其分界线的昏侧地心距离要大于晨侧的地心距离.模拟结果还显示随着Kp指数的增强,等离子体片中不同能量的质子分界线都向地球移动.但在低能端和高能端,质子分界线的行为是不一样的.在低能端,随着Kp指数的增大,质子内边界形状基本保持不变.但在高能端,随着Kp指数的增大,质子内边界形状也将发生变化.在E=20 keV,Kp=6和E=10 keV,Kp=3两种情况,质子分界线甚至出现了两个分离的区域,一个是环绕地球的封闭轨道区域,一个是晨侧孤立的锥型区域.等离子体片能量为E的质子的内边界就是具有不同磁矩的Alfven层上能量为E的点的连线.TC-1热离子谱仪对等离子体片离子内边界的观测显示模拟结果与观测结果符合得很好.     

日侧弥散极光对太阳风动压增强的响应

太阳风动压的显著变化能导致沉降进入极区电离层的能量粒子通量以及磁层-电离层电流系发生扰动。磁层高能粒子沉降到极区上层大气并与中性气体碰撞所激发的弥散极光,能够对这种扰动做出相应的响应。基于斯瓦尔巴特（Svalbard）群岛新奥尔松（Ny-?lesund）地区北极黄河站优越的地理优势,我们利用安装在黄河站的极光全天空成像仪观测到了日侧弥散极光对太阳风动压增强的响应。通过2006年1月2日事件观测显示,随着太阳风动压的增强,日侧弥散极光在极光卵赤道向部分首先点亮并逐渐向高纬扩展,同时地磁环境也受到相应扰动影响。我们认为,随着太阳风动压的增强,日侧磁层顶受到压缩,磁层内波粒相互作用导致投掷角散射增强,使得沉降进入极光卵赤道侧电离层的高能粒子数密度增大,进而导致日侧弥散极光强度增强。     

GNSS广播电离层模型在极区的改正效果分析

电离层时延为GPS测量中最棘手、最严重的误差源,而极区结构复杂波动较大,电离层延迟极大影响了GPS测量精度,故在极区选取一个简单有效的电离层模型极为重要。将GPS及BDS采用的不同Klobuchar模型以及Ne Quick模型计算的极区总电子含量,以欧洲定轨中心提供的GIM模型电离层产品作为参考标准,研究三种广播电离层模型在北极地区的均方根和模型改正率。选取了2009—2013年共计5年的时间数据进行分析。结果表明,纬度在57.5°以上地区电离层改正GPS系统采用的Klobuchar模型基本不适用,但改正效果依然优于BDS,而Ne Quick模型改正效果弱于中低纬度,改正率整体在40%左右。     

极区夏季中层顶尘埃分层的锐边界结构研究

火箭探空实验观测结果显示,极区夏季中层顶尘埃等离子体分层中存在着稳定的锐边界结构。本文采用了流体力学方程组和尘埃粒子自洽电荷变化模型,从尘埃等离子体电动力学的角度出发,利用数值模拟研究了尘埃分层结构中尖锐边界形成的物理过程。物理分析和数值模拟结果表明,中层顶区域存在的带电冰晶粒子在等离子体及电磁力等相互作用下,很容易形成一种在时间和空间上存在长时间,稳定的局域结构,这个结构可以用来解释我们观测到的一些实验现象。     

THE POLAR IONOSPHERE AND THE MAGNETOSPHERE-IONOSPHERE COUPLING

EISCAT (the Incoherent System at the northern polar region) data are used in discussion of the magnetosphere-ionosphere coupling. Comperison between samples in geomagnetic quiet days and during magnetic storms shows a significant effect of the basic magnetospheric processes on the features of the polar ionosphere. It not only demonstrates that the polar ionosphere can be regarded as a 'panoramic screen' of these process, but also indicates an importance of the simultaneous observation of southern and northern polar regions (especially, at the magnetic conjugate points). A few topics concerned are suggested for the further study of the southern polar region.