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1.
The cosmic ray geomagnetic cutoff rigidities are obtained by analytical calculations within an axisymmetric model of bounded magnetosphere, the magnetic field of which is created by the dipole field of the Earth and by two spheres located beyond the Earth with the currents that flow along the parallels and have a value proportional to the cosine of latitude. The inner sphere models the ring current flowing in the westerly direction; the outer sphere simulates the currents over the magnetopause, which flow in the easterly direction. The analytical results of calculations of variations in the geomagnetic cutoff rigidity for different levels of geomagnetic disturbances are given. The results are compared with the results of analytical calculations within the model of unbounded magnetosphere (when the outer sphere is absent). 相似文献
2.
Cosmic ray (CR) fluxes, which penetrate into the Earth??s magnetosphere and atmosphere from the interplanetary space, are an important factor of space weather. The geomagnetic field allows or forbids CR particles to enter into a given point in the magnetosphere depending on their energy. The geomagnetic cutoff rigidity regulates the distribution of CR fluxes in the magnetosphere. The geomagnetic cutoff rigidity (geomagnetic threshold) determination accuracy is closely related to the accuracy of the magnetospheric model used in calculations. Using a method for tracing of charged CR particle trajectories in the magnetic field of a model magnetosphere, we obtained geomagnetic thresholds for two magnetosphere empirical models (Ts01 and Ts04), constructed based on the same initial database. The Ts01 model describes the middle magnetosphere for certain conditions in the solar wind and interplanetary field. The Ts04 model pays the main attention to describing the large-scale evolution of magnetospheric currents during a storm. The theoretically obtained geomagnetic thresholds have been compared with experimental thresholds, calculated using the spectrographic global survey method based on data from the global network of CR stations. The study has been performed for the period of a strong geomagnetic storm that occurred in November 2003. 相似文献
3.
利用地磁场全球模型MF6, EMM2010和基于地面观测数据建立的2010.0中国地磁参考场(CGRF2010)等3个模型分别计算了中国大陆地区岩石圈磁场, 发现3个模型各有其特点: 基于卫星数据建立的MF6模型分辨率有限, 其磁异常条带呈蠕虫状; EMM2010模型岩石圈磁场概貌与MF6模型相似但细节特征十分突出; CGRF2010模型可信度较高, 其分辨率东西部差异较大, 异常形态以团状为主． 通过分析3个模型得到的中国大陆地区岩石圈磁场垂直分量ΔZ的强度及其分布特征发现: ΔZ分量在准噶尔盆地、 塔里木盆地、 柴达木盆地及四川盆地等地区均为正值, 而在天山、 大巴山等地区为负值; ΔZ分量分布在华北岩石圈地块与华南岩石圈地块吻合程度较高; 在青藏高原南部、 西域岩石圈地块北部以及松辽岩石圈地块, 全球模型与CGRF2010模型存在显著差别． 相似文献
4.
A simple method for obtaining a space-time model of the main magnetic field from the high-precision satellite survey data is described. At the first stage, the CHAMP satellite data for one-day interval are expanded into the spherical harmonics with constant coefficients. This yields a set of daily mean spherical harmonic models (DMSHM) over the survey interval of a few years. At the second stage, the coefficients of this set are used as source data for expansion into the natural orthogonal components (NOC). It is shown that the terms of the NOC series decrease rapidly, and the accuracy of the space-time model of the main geomagnetic field over the time interval under discussion is not worse than the accuracy of the models obtained by traditional methods. 相似文献
5.
卫星磁异常的理论模型 总被引：3，自引：3，他引：0
本文介绍了计算卫星磁异常理论模型的数学方法 ,即球谐分析方法、冠谐分析方法、矩谐分析方法和等效源方法 .根据相同的 MAGSAT资料 ,计算的卫星磁异常冠谐模型、矩谐模型和等效源模型都能很好地表示卫星磁异常的分布 .由于在整个研究区域 ( 1 0°N～60°N,70°E～ 1 40°E)都有卫星资料 ,所以这些理论模型没有所谓的“边界效应”.这一结论对计算地磁场的区域模型是很有意义的 . 相似文献
6.
随着地磁场模型的日趋完善和滤波技术的不断成熟,地磁匹配方法在近几年得到迅速发展,它一般用于近地卫星,还未用于海洋环境.针对这一问题,本文结合地磁场特点和海洋地磁测量的现状,分析了水下地磁匹配的可行性.分别从匹配的地磁模型和测量值中存在干扰磁场两方面,指出了制约该技术发展的几个因素.在此基础上,提出了地磁用于水下载体定位的两条技术途径,一是用小波变换滤去地磁异常,与大尺度地磁模型匹配定位;另外,也提出了利用地磁异常,结合同时定位与构图(SLAM)算法实现自主导航. 相似文献
7.
根据2003年中国地磁观测数据（包括135年地磁测点和35个地磁台）以及我国邻近地区38个IGRF计算点的地磁数据,计算中国地磁异常场的分布。选取两种地磁场模型作为地磁正常场,一是国际参考地磁场的球谐模型,二是中国地磁场泰勒多项式模型。根据各个测点的地磁异常值（观测值减去模型计算值）,用球冠谐分析方法计算地磁异常场的球冠谐模型,并绘制2003年中国地磁异常（△D,△I,△F,△X,△Y,△Z）。分析和讨论了中国地磁异常场。 相似文献
8.
V. V. Safargaleev D. N. Shibaeva T. I. Sergienko I. A. Kornilov 《Geomagnetism and Aeronomy》2010,50(7):873-879
The possibility of comparing in detail CLUSTER satellite data with data on pulsating spots registered with a TV camera at
the Lovozero Observatory when the satellite crossed the magnetospheric region related to the camera’s field of view is discussed.
The satellite ionospheric projections were calculated using the T89, T96, and T01 models. It was shown that the projection
allows us to judge with confidence whether or not a satellite will find itself in a region of pulsating auroras when only
the level of geomagnetic activity and the characteristics of the interplanetary medium are a priori known. When different
models are used in the projection, the spread is not less than the characteristic dimensions of the pulsating spots and can
be as high as 100 km. The corresponding satellite flight time is ∼4 min. Such a large spatial and time uncertainty does not
allow us to compare in detail the satellite data with ground-based optical measurements without a priori information on, e.g.,
the character of precipitation above a spot, as has been done by other researchers in the case of auroral arcs. The situation
becomes even more complex if a satellite is in the region of greatly stretched magnetic field lines. 相似文献
9.
N. I. Izhovkina 《Geomagnetism and Aeronomy》2013,53(3):329-336
A vortex structure renders additional stability to plasma irregularities stretched along magnetic field lines. Plasma irregularities extended over several tens of kilometers are registered with rocket and satellite equipment in the topside ionosphere. The registered scale of irregularities depends on the spatial and time resolution of the equipment used. Irregular structures were registered in the ionosphere during experiments with barium clouds and jets, when a plasma irregularity separated into strata extended over several meters and several kilometers across the geomagnetic field. It has been indicated that plasma vortices can be generated in an unstable plasma in a situation when its quasi-neutrality is disturbed. Local geomagnetic field disturbances will be caused by the appearance of a proper vortex magnetic field. Plasma vortices can interact in an inhomogeneous plasma with an unstable electron component. Such interactions are related to the transformation of the phase volume of free electrostatic oscillations in the frequency-wave vector space. 相似文献
10.
This paper describes a new method for reconstructing the polarity of the interplanetary magnetic field. The technique is based on the Svalgaard-Mansurov effect. We ause geomagnetic data of high-latitude stations with a long observation period, including the presatellite era. This method is designed to improve the quality and accuracy of reconstructed polarity, complementing the results of previous methods of Svalgaard (1975) and Vennerstr?m et al. (2001). For the large presatellite period from 1926, the accuracy of the method is estimated to be around 89% of overlaps with the interplanetary magnetic field polarity determined from satellite data. 相似文献
11.
准确的磁场模型对于辐射带粒子环境研究至关重要.本文利用美国Van Allen Probes（VAP）在2012至2018年期间测量的磁场数据和GOES15在2011至2017年期间测量的磁场数据,定量地评估了三个较新的外磁场经验模型（TS05、TA15和TA16）对外辐射带区域（3~6.6RE）磁场的描述性能.本文选择预测效率（Prediction Efficiency,PE）作为评估指标,定量分析各模型在不同空间范围（Lm值）、不同地磁活动水平（Kp）以及不同磁地方时（MLT）下的性能表现,并且计算了观测磁场与模型磁场的夹角θ,以评估模型的磁场方向预测能力.结果表明：PE随Lm值增大,随地磁扰动增强而下降;θ随Lm值增大,随地磁扰动增强而增大.在Lm=5~6.5RE范围内,PE呈现晨昏不对称性,MLT=12-21时的PE值小于MLT=0-9时的值,说明三个磁场模型可以较好地描述晨侧磁场的强度,但它们并不能很好地反映下午至昏侧磁场的大小;在地球同步轨道附近（Lm~6.6RE）,PE呈现昼夜不对称性,MLT=9-15时的PE值大于其他时区的值,说明三个磁场模型可以很好地反映昼侧磁场大小,但在夜侧可能存在较大的误差.θ在MLT=6-12时的值小于其他时区的值,呈现昼夜不对称性,说明三个磁场模型可以较好地描述昼侧磁力线的分布位型,但在夜侧存在较大的方向描述误差.在外辐射带3~6.5RE内,TA16模型与VAP磁场观测数据最为接近,PE均大于0.7,θ均小于3°;在地球同步轨道高度（6.6RE）,TS05模型与GOES15卫星磁场观测数据最为接近,PE约为0.75,θ约为7°.相关的研究结果可以为我国星载高能粒子探测器探测数据的在轨交叉定标、辐射带高能粒子动态模型研究和相关的磁层环境理论/应用研究提供地磁场模型选择方面的参考. 相似文献
12.
Malcolm G. McLeod 《Physics of the Earth and Planetary Interiors》1983,31(2):132-144
Two-dimensional Fourier spatial power spectra of equivalent magnetization values are presented for a region that includes a large portion of the western United States. The magnetization values were determined by inversion of POGO satellite data, assuming a magnetic crust 40 km thick, and were located on an 11 × 10 array with 300 km grid spacing. The spectra appear to be in good agreement with values of the crustal geomagnetic field spatial power spectra given by McLeod and Coleman (1980) and with the crustal field model given by Serson and Hannaford (1957). The spectra show evidence of noise at low frequencies in the direction along the satellite orbital track (N-S), indicating that for this particular data set additional filtering would probably be desirable. These findings illustrate the value of two-dimensional spatial power spectra both for describing the geomagnetic field statistically and as a guide for diagnosing possible noise sources. 相似文献
13.
The continuous spatial-temporal model of variations in the main geomagnetic field in the 20th century has been elaborated. All available data—from the navigation to the satellite surveys at the beginning and end of the century, respectively—have been used to construct the model. Since the accuracy of measurements was different during the century and the data are nonuniformly distributed over the Earth’s surface, the methods for regulating solutions based on global parameters of the magnetic field and its secular variation, invariant on the simulation interval, have been used to correct the model. The secular variation model has been represented as the sum of the models obtained by means of expansion in terms of natural orthogonal components. The conclusions that the character of field variations is complex have been made and the spatial and temporal characteristics of the secular variations of different origin have been estimated based on the simulation results. 相似文献
14.
Based on theoretical models of the ionosphere and the plasmasphere, the ion composition variations in the plasmasphere and the plasmapause structure were studied depending on the choice of the distribution model of the magnetospheric convection electric field at low and high geomagnetic activity at the equinox and the December solstice. Based on the model calculations performed, the plasmapause shape and size during an increase and decrease in geomagnetic activity were studied. It was revealed that the size of the plasmasphere mainly depends on the magnetic local time (MLT) sector and the level of geomagnetic activity, and it greatly depends on the maximum universal time during the equinox. The Earth’s plasmasphere asymmetry is manifested in the noon-midnight and morning-evening directions. The analysis results of daily and seasonal variations in the ionic composition of the Earth’s plasmasphere at a moderate solar activity level show that there is a certain increase in the ion concentrations of H+ and He+ in the winter period probably due to an increase in the exospheric density at the summer to winter transition. The data obtained are in good agreement with satellite observations which makes it possible to use the model proposed to study the plasmasphere under different geophysical conditions. 相似文献
15.
提出了用地磁总场对磁性目标定位的方法.以远场磁偶极子原理构建了地磁总场的测量阵列,设计了阵列对目标的定位算法,求解中采用二重梯度算法消除了地磁总场随时间变化和空间分布不均匀对目标定位的影响.实验验证了这种二重梯度算法的有效性.利用MATHCAD对定位算法中的非线性方程组进行了仿真,采用LINGO软件求解了阵列方程组.在松花江沿岸某地,用光泵磁传感器阵列对航行中的目标船进行了定位实验,所测磁场数据曲线与理论曲线完全吻合,证明了定位算法物理模型的正确性.提出了改进的磁场梯度偏置定位算法,进一步提高了目标定位精度.实验证明了这种地磁总场目标定位方法的可行性. 相似文献
16.
Based on ion distribution function found from the dynamic equation, the density distribution of He+ ions originating from the polar ionosphere and up-flowing along the magnetic field line is studied during quiet and weakly disturbed geomagnetic conditions. The results show the following. (1) The ionospheric up-flowing He+ ions mainly reside in the inner magnetosphere and their density has a negative radial gradient. (2) The ionospheric up-flowing He+ ion distributions along the magnetic field line are mainly controlled by gravity and the geomagnetic field configuration. Larger the gravity, larger is the ion density. Smaller the intensity of magnetic field, smaller is the ion density. (3) If the geomagnetic activity index Kp is high, more up-flowing He+ ions will enter the magnetosphere and the region where the up-flowing ions are dominant will grow. This is consistent with observations of ionospheric up-flowing ions. Some features of the geopause can be understood based on our theoretical results. 相似文献
17.
利用最新的波茨坦地磁场球谐模型(Potsdam Magnetic Model of the Earth,POMME)进行仿真实验,分别模拟出不同卫星轨道高度下的磁测数据.根据仿真的观测数据反演地壳磁场的高斯球谐系数,对反演结果进行对比和分析,总结出卫星轨道高度对反演结果的影响.针对CHAMP卫星实测数据进行地壳磁场反演,由不同轨道高度磁测数据反演得到的磁场(Magnetic Field,MF)系列模型,验证卫星轨道高度对反演的影响,从而为磁测卫星系统设计论证指标中的卫星轨道高度设计提供一定的参考和指导. 相似文献
18.
热层大气密度是空间大气环境的重要参数,经过多年的研究已开发了多种大气模式,但其误差普遍较大,尤其在磁暴期间偏差值甚至超过100%.本文利用中国星载大气密度探测器和CHAMP卫星加速度计在轨获得的连续探测数据,针对近10年(2003—2014)中多次强磁暴事件和多次中等强度扰动事件,即2003年11月、2004年7月和2005年8~9月多次强磁暴事件(Kp值均达到9),2006年4月、2012年4月的两次中等强度磁暴事件(Kp值分别达到7和6),分析和比对不同强度磁扰事件期间不同高度全球大气密度就位探测值与模式值(NRLMSISE00)之间的差别.在2005年8月24日强磁扰事件中,560 km高度中国卫星就位探测值上涨幅度约2~3倍,扰动区中的增变比高达5.7倍,375 km高度CHAMP卫星就位探测值上涨幅度约0.8倍,扰动区中增变比达4.0倍,期间大气密度模式值不仅没有出现明显的涨落,更没有出现强烈的区域扰动;在2003年11月和2004年7月的强磁扰事件中,CHAMP卫星就位探测值均有显著涨变和强烈扰动变化,而模式值无明显扰动变化;在中等强度磁扰事件中,高度560 km附近就位探测值在北、南半球高纬地区显著上涨,远高于模式值,高度350 km附近就位探测值在地球阴影区域显著上涨,上涨幅度也大于模式值.分析结果表明现有大气模式对地磁扰动(尤其是强磁暴事件)期间全球热层大气密度的响应并不明显,需要进一步改善. 相似文献
19.
The spatial-temporal model of the geomagnetic field has been constructed using the data of the high-accuracy survey of the CHAMP German satellite, obtained during its operation from May 2001 to September 2007. The daily average spherical harmonic models calculated at an interval of four days are used as initial data in order to expand these models by the method of natural orthogonal components (NOCs). It has been indicated that the obtained NOC series rapidly converges. The secular variations, secular acceleration, and Dst variation are distinguished as individual NOC components, which makes it possible to construct the spatial-temporal field model. In addition, the models-predictions have been constructed for the year 2008 based on the candidate models of the main field and the secular variation for the year 2005, which were used to obtain the IGRF2005 international model. A comparison of the models-predictions with the model constructed for the year 2008 using our method indicated that the accuracy of our model is not lower than that of the models, obtained by other scientific groups using the traditional method. 相似文献
20.
根据2000～2008年CHAMP卫星磁测数据,研究磁异常场建模中的卫星磁测数据通化技术,建立了川滇地区磁异常场的泰勒多项式模型,并和最新的磁异常场模型MF6做了比较。 相似文献