极光电激流的地方时和季节变化特性研究:CHAMP卫星观测

极光电激流是极区电流系的重要组成部分.本文利用CHAMP卫星10年的高精度标量磁场数据研究了极光电激流的地方时和季节变化特征,并对卫星与地面台站观测到的极光电激流进行了对比分析.结果表明,日侧极光电激流主要受太阳辐射的影响,而夜侧极光电激流主要受亚暴的影响.极光电激流具有明显的年、半年变化特征.夏季东向电激流和日侧西向电激流强于冬季,而夜间西向电激流冬季强于夏季.东向电激流和日侧的西向电激流在两至点增强,夜侧的西向电激流则在两分点增强.西向电激流与AL、SML指数有较好的相关性,东向电激流与SMU指数有较好的相关性,而与AU指数有一定差异,这与地磁台站的有效探测范围有关.     

磁暴期间热层大气密度变化

基于CHAMP卫星资料,分析了2002—2008年267个磁暴期间400km高度大气密度变化对季节、地方时与区域的依赖以及时延的统计学特征,得到暴时大气密度变化的一些新特点,主要结论如下:1)两半球大气密度绝对变化(δρa)结果在不同强度磁暴、不同地方时不同.受较强的焦耳加热和背景中性风共同作用,在北半球夏季,中等磁暴过程中夜侧和大磁暴中,夏半球的δρa强于冬半球;由于夏季半球盛行风环流造成的扰动传播速度快,北半球夏季日侧30°附近大气,北(夏)半球到达峰值的时间早于南(冬)半球.而可能受半球不对称背景磁场强度所导致的热层能量输送率影响,北半球夏季强磁暴和中磁暴个例的日侧,南半球δρa强于北半球;春秋季个例中日侧30°附近大气,北半球先于南半球1~2h达到峰值.2)受叠加在背景环流上的暴时经向环流影响,春秋季暴时赤道大气密度达到峰值的时间最短,日/夜侧大气分别在Dstmin后1h和2h达到峰值.至点附近夜侧赤道大气达到峰值时间一致,为Dstmin后3h;不同季节日侧结果不同,在北半球冬季时赤道地区经过更长的时间达到峰值.3)日侧赤道峰值时间距离高纬度峰值时间不受季节影响,为3h左右.在春秋季和北半球冬季夜侧,赤道大气密度先于高纬度达到峰值,且不同纬度大气密度的峰值几乎无差别,表明此时低纬度存在其他加热源起着重要作用.     

平流层爆发性增温期间赤道电集流中太阴潮汐的经度变化统计学研究

本文利用地磁台站和卫星磁场数据,对平流层爆发性增温(Sudden Stratospheric Warming,SSW)期间赤道电集流(Equatorial Electrojet,EEJ)中太阴半日潮汐的经度变化进行了统计学分析.结果显示,SSW期间秘鲁和印度扇区的EEJ中太阴半日潮汐明显增强,且存在显著的经度差异.秘鲁扇区的EEJ中太阴半日潮汐达到峰值的时间要早于印度扇区,进一步分析发现峰值时间的经度差异与太阳活动和准两年振荡相位有关.此外,SSW期间秘鲁扇区EEJ的太阴半日潮汐峰值强度比印度扇区高.对比不同经度带背景磁场的强度与太阴半日潮汐的峰值幅度的关系,可以看出SSW期间EEJ太阴半日潮汐峰值幅度的经度差异与背景磁场强度有关,但也存在其他物理过程的影响.     

第21太阳活动周地磁活动峰值的预计

1.计算并确定第21周地磁活动A_p的峰值 第21周太阳活动峰年已来到,国际上组织SMY联测活动。本文利用极值分布数学方法与经验规律相结合,对21周地磁活动A_p指数年均值的峰值及峰值时间作一定量预报,其结果与国外的预报作一比较。     

含激电效应的CSAMT一维正演研究

地电体对频率域电磁波激发源的响应为电磁感应和激电效应的综合响应.传统CSAMT法进行数据正反演时认为大地介质电阻率是与频率无关的实数,而实际上因为激电效应,地下可极化体的电阻率是一个与频率相关的复数.为推进二者总体响应研究,并扩展激电法的应用范围,同时提高电磁法勘探的精度,本文基于Dias模型,以复电阻率代替不考虑地电体极化效应的直流电阻率,对CSAMT场源一维层状模型进行了正演模拟,为提取CSAMT信号中所含激电信息提供理论基础.结果表明,考虑激电参数后,视电阻率及相位响应曲线出现明显异常（包括远场、过渡场、近场）;极化前后振幅比值异常峰值、相位差值异常峰值可直观体现激电异常;异常峰值与极化层层厚、埋深以及电阻率变化有连续的对应关系.认为从频率域电磁法信号中提取激电信息有乐观的前景.     

冕洞与太阳风高速流关系的统计研究:到达时间、持续时间和峰值强度

冕洞是太阳风高速流的源区.当冕洞出现在中低纬区域时,太阳风高速流会扫过地球并引发地球空间环境扰动,如地磁暴和高能电子暴等.在太阳活动周下降年和低年,这种类型的扰动占据主导地位.因此,冕洞高速流的到达时间、峰值时间、峰值强度和持续时间等,是空间天气预报的重要内容.本文基于2010年5月到2016年12月的SDO/AIA太阳极紫外图像以及1AU处ACE和WIND卫星的太阳风观测数据,确定了160个冕洞-太阳风高速流事件,定量计算了他们的特征参数,包括冕洞与太阳风高速流的开始时间、峰值时间、峰值强度和结束时间,分析了各个特征参数的分布规律,对冕洞-高速流之间的关系进行了统计研究,并提出了一种新的预报方法,为基于冕洞成像观测的太阳风高速流的精准预报提供了依据.     

宁洱6.4级地震灾情信息特征分析

选取2007年宁洱6.4级地震发生后一周内政府收集和上报的灾情档案资料中的人员伤亡和财产损失两类主要信息为基础资料,对该次地震的灾情信息特征进行初步分析.结果表明:灾情信息来源的主体为县级政府部门,描述方式以定量为主.在地震发生后4h内以定性描述为主,4～12h期间定性描述与定量描述都有,12 h后以定量描述为主;单位时间内灾情信息获知和上报的数量随时间的推移先逐渐增加,到达峰值后逐渐减少,最后趋于平稳;从信息随时间变化情况来看,最先掌握死亡人员数量,接着是重伤人员数量,最后是受伤人员数量;与地震灾害直接经济损失评估结果比较,房屋损失信息更直接地反应本次地震损失.     

太阳黑子对厄尔尼诺、拉尼娜的影响

本文分析了太阳黑子、日食、厄尔尼诺和拉尼娜现象之间的关系，指明了用太阳黑子和日食情况来预测厄尔尼诺和拉尼娜现象在时间上和强度上，都可有很高准确性，太阳黑子峰值年影响日食形成的厄尔尼诺加强，拉尼娜减弱，谷值年相反。     

基于DPHP测量数据提取热导率参数的方法研究

基于DPHP实测数据研究了提取热导率参数的两种方法:极值法和拟合法.极值法利用温度曲线的峰值及对应时间计算热导率,测量过程中的采样间隔是影响计算结果的关键因素,热导率相对误差同采样间隔与峰值时间的比值有关,当比值小于0.02时,相对误差不超过±1%.采用抛物线拟合采样最大温度值相邻的数据计算峰值温度能够在一定程度上弥补采样率过大的问题.但对于过大的采样间隔获得的数据应使用非线性拟合法.非线性拟合法要求拟合模型对实测数据有良好反映,但理论模型与实际探针模型的差异导致实测数据只是在最大温度前后吻合较好,因此需要对拟合数据窗口进行选择.基本原则是数据区间内应当包含温升最大值,而且上升段的数据量应少于衰减段的数据量.     

探讨FD-125水氡仪观测静置最佳时间的选取

以崇明地震台观测井FD-125测氡仪观测资料为基础,结合笔者的工作实践,设计不同的观测实验,探讨FD-125测氡仪的氡测值与不同静置时间之间的关系,找出最佳的静置时间。实验结果表明,在1~3h内,测值与静置时间成正比,3h左右达到峰值;之后,测值随着静置时间的增加而减小。     

Effects of solar and geomagnetic activities in variations of power spectra of electrical and meteorological parameters in the near-Earth atmosphere in Kamchatka during October 2003 solar events

We perform spectral analysis of records of meteorological (temperature, humidity, pressure of the atmosphere) and electrical (strength of quasi-static electric field and electric conductivity of air) parameters observed simultaneously at the Paratunka observatory during the solar events of October 21–31, 2003. Also, we use simultaneous records of X-ray fluxes of solar radiation, galactic cosmic rays, and the horizontal component of the geomagnetic field. We show that the power spectra of the meteorological parameters under fine weather conditions involve oscillations with a period of thermal tidal waves (T ～ 12 and 24 h) caused by the influx of thermal radiation of the Sun. During strong solar flares and geomagnetic storm of October 29–31 with a prevailing component of T ～ 24 h, their spectra involve an additional component of T ～ 48 h (the period of planetary-scale waves). With the development of solar and geomagnetic activities, the power spectra of atmospheric electric conductivity and electric field stress involve components of both thermal tidal and planetary-scale waves, which vary highly by intensity. In the power spectra of galactic cosmic rays accompanying the strong solar flares, components with T ～ 48 h were dominant with the appearance of additional (weaker by intensity) components with T ～ 24 h. The simultaneous amplification of components with T ～ 48 h in the power spectra of electric conductivity and electric field strength provides evidence of the fact that the lower troposphere is mainly ionized by galactic cosmic rays during strong solar flares and geomagnetic storms. The specified oscillation period with T ～ 48 h in their spectra, as well as in the spectra of X-ray radiation of the sun, is apparently caused by the dynamics of solar and geomagnetic activities with this time scale.     

The equatorial electrojet

The typical quiet day variations of the equatorial electrojet (EEJ) current intensity with time of the day, season, sunspot number, and geomagnetic latitude are presented in terms of the corresponding variations of H which is the deviation of the horizontal component (H) of the geomagnetic field from its steady nighttime level. The observed height structure of the current density in the EEJ as measured in rocket flights is presented, along with the theoretically computed structure. Theoretical model results on the polarization electric fields and east-west currents as generated by the local interactions of height-varying winds in the EEJ show large height gradients and reversals for both currents and electric fields; experimental evidence for the reality of such height structures is also shown. The characteristics of the counter-electrojet events are presented and the possible causative mechanisms are discussed critically.Some typical experimental results are presented on the electric field changes in the EEJ which result from its sensitive response to electrodynamic disturbances in the magnetosphere and the auroral-polar latitude ionosphere during geomagnetic substorms and storms; and their implications are discussed. Possibilities for utilizing the EEJ as a very useful medium for important scientific studies on the larger space domain of ionosphere-magnetosphere system, on plasma waves, and on the earth's conductivity are emphasized.     

Local time and longitude dependence of the equatorial electrojet magnetic effects

An empirical model of the equatorial electrojet (EEJ), including local time and longitude dependence, has been constructed based on the surface magnetic data recorded at 26 stations located in six different longitude sectors that were set up or augmented during the international equatorial electrojet year (IEEY). The model reproduces the characteristic signatures of the EEJ-associated horizontal and vertical magnetic components at ground level. The model-predicted variations at the orbit of the POGS satellite are generally in good agreement with the onboard magnetic signatures, although strong discrepancies are also often seen. The nature of the differences suggests that the global scale magnetospheric or field-aligned current systems may sometimes dominate the satellite data. The nature of the longitudinal inequalities in the EEJ strength indicates that the equatorial electrojet is strongest in South America (80°–100°W) and weakest in the Indian sector (75°E) with a secondary minimum and a maximum centered, respectively, in the Atlantic Ocean (30°W) and in western Africa (10°E). The EEJ strength is shown to be inversely correlated with the main field intensity along the dip-equator.     

基于Weimer模型的高纬地磁扰动预测

地磁扰动是空间天气中的重要现象,对地基技术系统具有重要的影响.准确预报地磁扰动可以有效避免重大灾害发生.本文基于Weimer电势和磁势模型发展了高纬地区地磁扰动的模拟方法,并与地面台站观测数据进行了比较.地表磁场扰动主要受电离层电流系统的影响,利用Weimer模式计算出电离层等效电流分布后,基于毕奥-萨伐尔定律推导了地磁扰动三分量与电流的关系,最终计算出地磁扰动量.模型的输入参数为太阳风速度、太阳风密度、行星际磁场和磁偶极倾角.模型计算结果与不同纬度和经度的地磁台站观测结果对比表明本文的计算方法能有效地模拟地磁暴期间地磁扰动特征.本文结果对今后发展高纬地区地磁场预报模型奠定了重要基础.     

The equatorial and low-latitude ionosphere within the context of global modeling

The thermosphere–ionosphere–mesosphere-electrodynamics coupled model TIME-GCM, coupled to NCEP lower atmosphere data, is used to simulate the noontime ionospheric peak electron density NmF2 at low latitudes for year 2002. Model output are compared with observations a three ionosonde stations: Jicamarca, Ascension Island and Darwin, stations at geomagnetic latitudes of 3°S, 10°S and 22°S, respectively. The modeled electron density at the peak of the F2-layer (NmF2) matches the general trend of the data fairly well at noon throughout the year. The shapes of the diurnal curves of NmF2 vs. local time are not well produced in the model, and particularly so at the two stations away from the geomagnetic equator. At all sites the day-to-day variability of NmF2, assessed using the percent standard deviation about the monthly mean, is about twice the modeled variability. Possible sources of this shortfall in the model may be due to the under-representation of coupling from below and/or from auroral sources.     

Plumes of the plasmasphere and variations in the geomagnetic field horizontal component

The effects of the dayside and dusk plumes of the plasmasphere during the ring current recovery phase on the disturbance level of the ground geomagnetic field horizontal component have been considered. It has been indicated that the geomagnetic field horizontal component changes specifically and synchronously in the region corresponding to the plasmaspheric dayside plume. Outside the plume the time variations in the geomagnetic field horizontal component pronouncedly differs. A spectral analysis of disturbances in the geomagnetic field horizontal components in the range of geomagnetic pulsations indicated that the intensity in the range of Pc4 pulsations increases at magnetic stations located on field lines corresponding to the dayside and dusk plumes of the plasmasphere. These pulsations detected in the dynamic spectrum of the geomagnetic field horizontal components in the dayside plume region of the plasmasphere, probably reflect the resonance oscillations of magnetic field lines in the region of field-aligned currents at comparatively low altitudes. We assume that this is caused by the instability of field-aligned currents originating as a result of the interaction between the ring current energetic ions and electromagnetic waves in the region with a relatively dense background plasma of the dayside plume.     

变化地磁场预测的支持向量机建模

变化地磁场建模与预测是地磁导航、空间环境监测等领域的重要研究课题.由于变化地磁场属于日地系统中的一部分,受多种因素的制约影响,且其变化本身也具有较强的前后相关性.本文综合空间和地面监测数据,以变化地磁场地面观测数据、地方时、太阳射电流量和行星际磁场南向分量等为输入,采用支持向量机方法,建立了变化地磁场综合模型,并进行预测.结果表明,在地磁活动Kp指数小于4时,预测3 h平均绝对误差小于1.61 nT.     

边界点选取对蒙古地磁场球冠 谐和模型精度的影响

中国地震局地球物理研究所与蒙古科学院天文与地球物理研究中心于2011—2012年合作开展了蒙古119个野外地磁测点的测量工作. 本文利用蒙古119个测点准确可靠的地磁数据, 分别加上9组边界点EMM2010模型计算值, 得到了蒙古2010.0年代地磁异常场的9个球冠谐和模型; 给出了地磁异常场北向分量ΔX、 东向分量ΔY和垂向分量ΔZ的等值线分布图, 并比较分析了这9个模型的异同; 同时计算了119个测点的地磁测量值与模型计算值之差的均方根误差σ, 以σ为指标来表征这9个模型的精度, 由此定量评价了边界点选取对模型精度的影响. 结果表明, 适当引入边界点能够提高模型精度, 而远离测区3°—5°的均匀边界点也能起到改善模型精度的作用. 因此在实际建模时, 应当在计算区域边界引入适当的边界点, 以改善地磁模型的精度.      

京津冀地区地磁场球冠谐分析

2002年在京津冀地区进行了45个测点的地磁三分量测量,对测量资料进行通化处理,通化时间为2002年5月5日16～18时（世界时）. 通化后的观测均方差分别优于1.5nT（地磁场总强度F）,0.5′(磁偏角D和磁倾角I). 将国际参考地磁场（IGRF2000）作为地磁正常场,建立了京津冀地区地磁异常场的球冠谐模型（BTHASCH）. 球冠极的空间位置坐标为39.5°N和117.0°E,球冠半角为4°. 在模型计算过程中,球冠谐函数的截断阶数分别取为1～10. 经综合比较, 最终采用的截断阶数为5. 建立了京津冀地区参考地磁场的球冠谐模型（BTHGRF）.根据模型,绘制了京津冀地区地磁异常场图(ΔX、ΔY、ΔZ、ΔF、ΔD、ΔI)和京津冀地区地磁图(X、Y、Z、F、D、I).     

二维电离层发电机理论模式及其初步应用

在地理坐标系下推导出二维电离层发电机理论方程,采用逐线迭代法求解得到全球二维电离层发电机电流函数,进而得到电离层发电机电流和电场.模式中使用的电导率是根据外部经验模式给出的背景大气和电离层参数,采用理论公式计算得出;输入的中性风场和磁场分别由HWM93和IGRF2000模型给出,该电离层发电机理论模式很好地给出了全球Sq电流形态及电离层E层发电机电场的基本特征.利用该模式研究了外部模式风场以及地磁场随高度的变化对模拟结果的影响,发现在90~180 km高度上,风场随高度变化对电流影响较大,而地磁场影响较小;重点模拟研究了地磁平静时期,Sq电流涡旋中心位置和总电流强度的变化规律,初步研究发现,电流中心位置在地理纬度±30°附近,不同的地方时电流随地磁纬度线平行移动,且南北半球两个电流涡中心电流强度之和变化不大.分析发现这种规律与发电机高度上的磁场总强度及地磁倾角的全球分布有很好的相关性.