Magnetospheric dynamics during the storm of February 14, 2009

The structure of the magnetic field in the magnetospheric during the storm of February 14, 2009 is studied. The model parameters that characterize the magnetospheric magnetic field are calculated every hour on the basis of solar wind data and the evolution of the magnetic field during the storm is reproduced using the A2000 model of the Earth’s magnetosphere. It is shown that extremely quiet geomagnetic conditions in 2009 promoted the expansion of the magnetosphere and were favorable for the formation of magnetic-island-like structures (plasmoids) in the geomagnetic tail. It is ascertained that negative variations in the B_z component could occur in the nightside magnetosphere in situations where the magnetic flux through the tail lobes exceeded certain thresholds, which depend on the parameters of the magnetospheric current systems. It is shown that the formation of magnetic islands decreases the magnetic flux through the tail lobes and prevents excessively strong development of the magnetic field in the tail.     

Variations in the geomagnetic cutoff rigidity of CR in the period of magnetospheric disturbances of May 2005: Their correlation with interplanetary parameters

The correlation between the rigidities of a geomagnetic cutoff, obtained using the global spectrographic survey method, and by trajectory tracing of CR particles in the magnetic field of the Ts03 Tsyganenko magnetosphere model (2001–2003) and the Dst variation and interplanetary parameters, was studied for the May 15–19, 2005, period of interplanetary and geomagnetic disturbances.     

The effect of plasma drift on the electromagnetic cyclotron instability

It is shown that the drift of plasma across a homogeneous magnetic field causes the generation of a wave electric field which, for waves propagating along the magnetic field in the whistler mode, is in the direction of the magnetic field. This leads to Landau damping of the wave field by the background electron distribution, simultaneously with amplification via the electromagnetic cyclotron instability. The drift velocity of the plasma for zero net growth of a whistler mode signal is calculated. It is suggested that such a process occurs in the equatorial region of the magnetosphere during a geomagnetic storm and accounts for the missing band of emissions at half the equatorial gyrofrequency.     

Poynting flux impulses and the ionospheric switching of geomagnetic substorms

Observations were made of impulse events in Poynting flux calculated from electric and magnetic disturbances encountered by the Polar satellite when on high-latitude field-lines in the magnetotail. These were found to be coincident within±6 min with impulsive spikes in cosmic radio background absorption in the D region of the ionosphere as detected by the Imaging Riometer for Ionospheric Studies riometer in Finland. They were also coincident with substorm onset at the same geomagnetic latitude as determined by a change of gradient in International Monitor for Auroral Geomagnetic Effects’ X-component magnetograms. The interpretation of the observations was that magnetospheric compression waves from the geomagnetic equator region of the magnetotail were coupling to progressively initiate field-guided Alfvén shear waves towards higher geomagnetic latitudes over a large volume of the magnetosphere. The study suggested that they were then able either directly or indirectly to ionise the D region of the ionosphere and in the process to cut deep electrically conducting channels between the magnetosphere and the ionosphere through which currents could flow and initiate the characteristic signature of geomagnetic substorms in ground magnetograms.     

Satellite observations of electric fields in the innermagnetosphere and their effects in the mid-to-low latitude ionosphere

During geomagnetic disturbances, momentum and energy are transferred in significant quantities from interplanetary space to the magnetosphere-ionosphere system through the mediation of charged particles and electric fields. The most dramatic manifestations occur in the plasma sheet and the conjugate auroral ionosphere. However, electric fields observed during magnetic storms also penetrate the inner magnetosphere that maps to subauroral latitudes in the ionosphere. For example, a sudden commencement shock wave initiating the March 1991 magnetic storm created a new radiation belt within minutes. Particle and field measurements by Combined Release and Radiation Effects Satellite (CRRES) near the equatorial plane of the magnetosphere and by Defense Meteorological Satellite Program (DMSP) satellites in the topside ionosphere during the magnetic storm of June 1991 indicate that penetration electric fields energized the stormtime ring current and rapidly transported plasma within subauroral ion drift (SAID) structures at midlatitudes and in upward drafting plasma bubbles at low latitudes. Through enhanced transport or chemical reactions, the SAIDs dug deep plasma troughs at topside altitudes. Equatorial plasma bubbles developed while the ring current was unable to shield the electric field from the innermost magnetosphere     

地磁暴对电力系统的影响及防治策略

地磁暴是全球范围内地球磁场的剧烈扰动现象, 在电网中产生地磁感应电流(GIC)。电力变压器在GIC的作用下进入半波饱和状态, 其产生的谐波和增加的无功损耗影响电网电压稳定, 造成系统中继电保护装置误动, 随着电网电压等级的提高和电网规模的扩大, 地磁暴可能严重威胁电网安全运行。分析了变压器对GIC入侵后的响应, 以及次生灾害在电力系统中的传播过程, 阐明了磁暴对电力系统的影响机理, 分析了GIC对变压器、无功补偿设备和继电保护装置等设备的影响, 建立了GIC对系统电压稳定性影响的分析框架及基本方法, 最后提出了一种GIC优化治理策略, 与传统治理方法相比具有明显的优越性。     

计及地磁暴影响的电力系统事故链仿真模型

地磁暴影响下地磁感应电流(GIC) 流过变压器中性点, 引起变压器无功损耗增加, 在强地磁暴环境中, 系统的无功补偿装置可能过载, 母线电压下降, 可能引发连锁故障, 继而导致大停电事故。对比事故链各环节特点和因磁暴导致的电力系统停电事故的发展规律, 使用事故链模型来仿真实现地磁暴条件下的电网停电过程。基于自组织临界理论和非故障线路的安全稳定裕度来确定连锁故障的传播路径。结合IEEERTS79系统参数, 估算各母线的地理位置, 借助PowerWorld仿真软件, 以该系统为例, 研究结果验证了所提事故链模型可以反映给定电网条件下, 地磁暴参数对电力系统事故链集与薄弱环节辨识的影响, 研究结果可为量化和防治磁暴电网灾害提供依据。     

Effect of NO concentration disturbances on the global distribution of ionospheric parameters during geomagnetic storms

The role of nitric oxide (NO) in the ionospheric effects during geomagnetic storm on May 1–3, 2010, is examined. The studies are performed using a global self-consistent model of the thermosphere, ionosphere and protonosphere (GSM TIP). Two versions of calculations are used: (1) based on an analytical approximation of the NO concentration and (2) self-consistent calculation of the global distribution of nitric oxide over the ionosphere. It is shown that, during a geomagnetic disturbance, the NO concentration at high latitudes shows an increase, which under the influence of the horizontal circulation of neutral gas leads to an increase in the concentration of NO at mid-latitudes ～1 day after the start of the perturbation. Simulated values of foF2 are compared to experimental data obtained at a number of Russian mid-latitude stations. It is noted that the self-consistent calculations of the NO concentration better describes the spatial-temporal behavior of ionospheric parameters during geomagnetic storms.     

Proton loss of inner radiation belt during geomagnetic storm of 2018 based on CSES satellite observation

The proton distribution in inner radiation belt is often affected by strong geomagnetic storm disturbance. Based on the data of the sun-synchronous CSES satellite, which carries with several high energy particle payloads and was launched in February 2018, we analyzed the extensive proton variations in the inner radiation belt in a wide energy range of 2 MeV-220 MeV during 2018 major geomagnetic storm. The result indicates that the loss mechanism of protons was energy dependence which is consistent with some previous studies. For protons at low energy 2 MeV-20 MeV, the fluxes were decreased during main phase of the storm and did not come back quickly during the recovery phase, which is likely to be caused by Coulomb collision due to neutral atmosphere density variation. At higher energy 30 MeV-100 MeV, it was confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon during this storm. At highest energies > 100 MeV, the fluxes of protons kept a stable level and did not exhibit a significant loss during this storm.     

Effect of strongly perturbed magnetosphere on the cosmic-ray cutoff rigidity

Comprehensive determination of the cosmic-ray cutoff rigidity in strongly perturbed periods has been performed for a number of stations located at different latitudes. To calculate the geomagnetic cutoffs by tracing the trajectories of cosmic-ray particles in the magnetic field of the magnetosphere, the model of strongly perturbed magnetosphere was used [1–3]. The diurnal anisotropy of the geomagnetic cutoff rigidity in the minimum of D _st variation in the geomagnetic field has been estimated.     

Strong cosmic ray cutoff rigidity decreases during great magnetospheric disturbances

The theoretical and experimental cosmic ray cutoff rigidities during great magnetospheric disturbances in November 2004 and May 2005 have been determined. The theoretical geomagnetic cutoffs were calculated by the trajectory tracing method in the magnetic field of Tsyganenko’s magnetospheric model T03, which describes great magnetospheric disturbances (at Dst < 65 nT). The experimental geomagnetic cutoffs were determined by the spectrographic global survey method on the basis of the world network data. The cutoff rigidity decreases at Dst minima can reach 70–80% for theoretical cutoffs and ～40% for experimental cutoffs at mid latitudes.     

Microwave radiation in the upper atmosphere of the earth during strong geomagnetic disturbances

The influence of N₂ and O₂ molecules on spontaneous microwave radiation spectrum was studied over the decimeter range. This radiation appears in the D and E upper earth atmosphere layers during strong magnetic storms. It was shown to be caused by radiation transitions between medium-perturbed orbitally degenerate Rydberg atom and molecule states A** that occur without changes in the principal quantum number, δn = 0. The available experimental data were used to calculate the dependences of orbitally degenerate state populations on the density of medium and electron flux and temperature. Effective radiation bands were constructed for transitions between highly excited quasi-molecule levels A**N₂ and A**O₂. The emission spectrum was shown to be inhomogeneous and contain three frequency regions in which a noticeable decrease in the intensity of radiation occurred. The physical reason for the formation of these regions was a shift of the emission spectra of quasi-molecules containing unexcited N₂ and O₂ molecules. The frequency profiles of radiation intensity within these frequency regions were calculated as depending on the storm level. Radiation profiles were shown to noticeably change as the storm level increased, they strongly increased close to the right region edge corresponding to high transition frequencies. Nonmonotonic behavior of this profile in the middle of the lower region was observed; this was related to emission spectrum inhomogeneity. A sharp increase in radiation intensity as the magnetic storm level increased occurred in the region of frequencies situated close to the right edge of the upper region (50–100 GHz), which was most interesting for biophysical studies of the action of microwave radiation on living organisms during strong geomagnetic disturbances.     

光磁共振实验中抵消地磁场垂直分量的方法

介绍了光磁共振实验装置的各磁场线圈,分析了光磁共振实验中抵消地磁场垂直分量传统方法的缺陷,利用垂直磁场对磁共振信号的影响,提出了一种重复性较好的抵消地磁场垂直分量的方法,减小了传统实验方法产生的误差.这种方法也可用于测量地磁场垂直分量的大小.     

Ionospheric effects of geomagnetic storms at mid latitudes

Previously, we studied the ionospheric effects of the sequence of geomagnetic storms on September 9–14, 2005 using a global self-consistent model “Thermosphere-Ionosphere-Protonosphere” (GSM TIP). Differences between the predicted and observed effects of the ionospheric storms may be due to the use of the three-hour K _p index of geomagnetic activity in modeling the time dependence of model input parameters, use of the dipole approximation of the geomagnetic field, and disregard in simulations for solar flares that occurred during this period. We tried to eliminate two of these three reasons. First, we used the A _E index of geomagnetic activity with minute resolution in modeling the time dependence of the model input parameters. Second, we took into account the effects of solar flares. In addition, GSM TIP model was supplemented by an empirical model describing the precipitation of high-energy electrons. The results of the simulation of the behavior of various ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill, and Arecibo stations on September 9 and 10, 2005 in the new formulation of the problem, presented in the current work, are in better agreement with the available experimental data than the results of previous calculations.     

On the structure of the middle Jovian magnetosphere

A model of the plasma distribution in the middle Jovian magnetosphere is considered. The distribution of the background plasma along the magnetic lines of force under the action of the centrifugal force and the force of gravity is analyzed in the framework of the diffusive equilibrium, taking into account the finite angle between the magnetic and rotational axes. It is shown that the dense structures of the background plasma have the form of a warped sheet located between the magnetic and centrifugal equators, and of two mirror symmetrical petals in the vicinity of the polar cusps. The hydrodynamic stability of the dense plasma sheet, formed under the action of the centrifugal force, is studied. The steady state radial plasma distribution at the threshold of the instability with respect to the small-scale MHD perturbations is determined. The finite conductivity of the Jovian ionosphere is taken into account. The influences of the longitudinal inhomogeneity of the perturbations, the finite ion Larmor radius, and the curvature of the magnetic field lines on the threshold of the instability are estimated. Some aspects of the formation of the energetic particle distribution in the middle Jovian magnetosphere are considered. The suggested model shows reliable agreement with the known experimental data and is also useful in describing the background plasma distribution in the magnetospheres of Neptune and Uranus.Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Traslated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 5, pp. 580–595, May, 1994.     

Model of geomagnetic field variations at the period range from 4 days until 3 years

Summary The field of the ring current in the magnetosphere is approximated by the spherical harmonicP ₁ ⁰ on the Earth’s surface. The authors analyse the choice of the coordinate system, where the spherical harmonicP ₁ ⁰ is determined, and test the technique of determining the pole position of the system by rotating the original axes in a set of observatories. The pole position was determined from the daily mean values (1969–1971 years) and the monthly mean values (1957–1978 years). The model ofP ₁ ⁰ source in this system was verified by the horizontal magnetic field variations in time range from 4 days to 3 years. The results allow us to use the model ofP ₁ ⁰ source for deep magnetovariation sounding in a coordinate system, which is close to the geomagnetic system at least for the analysed time intervals. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Memorandum on non-curl-free geomagnetic field

Summary In 1939 Schmidt denied the presence of nonpotential geomagnetic field observed on the Earth’s surface, after stating that the nonvanishment of curl _z B must be merely a consequence of remaining errors in geomagnetic observations. His paper was so influential that the discussion on nonpotential magnetic field disappeared ever since. The apparent nonvanishment of curl _z B (calculated from the differences of observed magnetic-field values at neighbouring meshpoint stations) would be, however, more reasonably attributable to a possible small-scale inhomogeneity in underground magnetic susceptibility or/and electric conductivity, whose spatial wavelength is shorter than the distance between observation meshpoints. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Variations in the Geomagnetic Cutoff Rigidity during the Magnetic Storm in March 2015

Variations in the planetary system of the geomagnetic cutoff rigidity during the moderate geomagnetic storm in March 2015 are calculated on the basis of data from cosmic-ray measurements at the world network of stations. The distance to the subsolar point and the radius of the ring current are calculated on the basis of the axisymmetric restricted Earth’smagnetosphere model that takes into account currents at the magnetopause and the ring current. The contribution of the ring current to variations in the geomagnetic cutoff rigidity and to the disturbance storm time (Dst) index is also determined within this model.     

埋地油气管道地磁感应电流(GIC)的混沌特性研究

空间天气影响下的钢制油气管道会产生地磁感应电流,地磁感应电流能够加速管道腐蚀,干扰管道监测装置,危及人身安全.为了研究管道地磁感应电流的非线性动力学特性,首先基于线传输理论,建立了管道地磁感应电流模型,并应用Melnikov方法对模型进行分析,揭示了地磁场与管道系统相互作用而产生混沌的机理,指出管道地磁感应电流具有出现混沌的可能性.其次,以中国西气东输一线管道中卫处6次磁暴事件数据为例,依据功率谱分析法、主分量法、关联维数法、Lyapunov指数法等多种混沌判别方法,对计算得到的地磁感应电流时间序列作了定量和定性的分析,进一步验证理论分析的结果.数学模型和实际数据两方面都表明:在空间天气影响下,埋地钢制管道系统内的地磁感应电流具有混沌特性,为空间天气影响下的钢制油气管道保护提供了理论依据.