Recent geomagnetic storms observed by Macao Science Satellite-1

Geomagnetic storms are rapid disturbances of the Earth’s magnetosphere.They are related to many geophysical phenomena and have large influences on human activities.Observing and studying geomagnetic storms is thus of great significance to both scientific research and geomagnetic hazards prevention.The Macao Science Satellite-1(MSS-1)project includes two high-precision Chinese geomagnetic satellites successfully launched on May 21,2023.The main purpose of MSS-1 is to accurately measure the Earth’s magnetic field.Here,we analyze early MSS-1 geomagnetic field measurements and report observations of two recent geomagnetic storms that occurred on March 24,2024 and May 11,2024.We also calculate the related geoelectric fields as an initial step towards a quantitative assessment of geomagnetic hazards.

Global distributions of storm-time ionospheric currents as seen in geomagnetic field variations

To investigate temporal and spatial evolution of global geomagnetic field variations from high-latitude to the equator during geomagnetic storms, we analyzed ground geomagnetic field disturbances from high latitudes to the magnetic equator. The daytime ionospheric equivalent current during the storm main phase showed that twin-vortex ionospheric currents driven by the Region 1 field-aligned currents （R1 FACs） are intensified significantly and expand to the low-latitude region of-30~ magnetic latitude. Centers of the currents were located around 70~ and 65~ in the morning and afternoon, respectively. Corresponding to intensification of the R1 FACs, an enhancement of the eastward/westward equatorial electrojet occurred at the daytime/nighttime dip equator. This signature suggests that the enhanced convection electric field penetrates to both the daytime and nighttime equa- tor. During the recovery phase, the daytime equivalent current showed that two new pairs of twin vortices, which are different from two-cell ionospheric currents driven by the R1 FACs, appear in the polar cap and mid latitude. The former led to enhanced north- ward Bz （NBZ） FACs driven by lobe reconnection tailward of the cusps, owing to the northward interplanetary magnetic field （IMF）. The latter was generated by enhanced Region 2 field-aligned currents （R2 FACs）. Associated with these magnetic field variations in the mid-latitudes and polar cap, the equatorial magnetic field variation showed a strongly negative signature, produced by the westward equatorial electrojet current caused by the dusk-to-dawn electric field.

Day-to-Day Variability of H Component of Geomagnetic Field in Central African Sector Provided by Yaoundé-Cameroon Amber Station

The geomagnetic data obtained from Amber Network station in Cameroon have been used for this study. The variability of H component of geomagnetic field has been examined by using geomagnetic field data of X and Y components recorded at AMBER magnetometer station hosted by the Department of Physics of University of Yaoundé (3.87°N, 11.52°E). The day-to-day variability of the horizontal intensity of the geomagnetic field was examined and shows that the scattering of H component of magnetic field variation is more on disturbed than that on quiet condition. The signatures H of geomagnetic Sq and Sd variations in intensities in the geomagnetic element, has been studied. This study shows that the daytime variations in intensities of geomagnetic elements H, Sq(H) and Sd(H) respectively are generally greater than night-time ones. This paper interests answering the two questions: 1) how can geomagnetic variations be used to study the equatorial ionosphere electrodynamics and electrojet equatorial over Africa in general and Cameroon in particular? 2) How can geomagnetic variations be used to monitor and predict space weather events in Cameroon? This paper presents and interprets the results of H component of geomagnetic field variations during magnetic storms and on quiet days.

Relation between Solar Wind Parameter and Geomagnetic Storm Condition during Cycle-23

In the present paper dependence of geomagnetic activity on the solar-wind plasma and interplanetary magnetic field (IMF) parameters has been studied. We have taken interplanetary solar wind data at the instant of Dst minimum. Our study consists of 200 geomagnetic storms weighed by disturbance storm time (Dst) -50 nT, observed during solar cycle 23. The study suggests that the strength of the geomagnetic storm is strongly dependent on the total magnetic field Btotal. The correlation (-0.72) has been found reasonable. In perspective of previous studies, the strength of the geomagnetic storm is strongly dependent on the southward component (Bz) whereas in present study exposes that the correlation (0.22) is weak. This result indicates that solar wind southward magnetic field component Bz has significant growth particularly before the main phase of geomagnetic storm (not during the main phase). The present result implies that neither density nor temperature is significantly related to the variation of geomagnetic disturbance;rather the effects of the pressure and speed. However, a low plasma beta during highly geoeffective event seems to be an important criterion.

A Nonlinear Autoregressive Approach to Statistical Prediction of Disturbance Storm Time Geomagnetic Fluctuations Using Solar Data

A nonlinear autoregressive approach with exogenous input is used as a novel method for statistical forecasting of the disturbance storm time index, a measure of space weather related to the ring current which surrounds the Earth, and fluctuations in disturbance storm time field strength as a result of incoming solar particles. This ring current produces a magnetic field which opposes the planetary geomagnetic field. Given the occurrence of solar activity hours or days before subsequent geomagnetic fluctuations and the potential effects that geomagnetic storms have on terrestrial systems, it would be useful to be able to predict geophysical parameters in advance using both historical disturbance storm time indices and external input of solar winds and the interplanetary magnetic field. By assessing various statistical techniques it is determined that artificial neural networks may be ideal for the prediction of disturbance storm time index values which may in turn be used to forecast geomagnetic storms. Furthermore, it is found that a Bayesian regularization neural network algorithm may be the most accurate model compared to both other forms of artificial neural network used and the linear models employing regression analyses.

A Magnetic Disturbance Compensation Method Based on Magnetic Dipole Magnetic Field Distributing Theory

The interference of carrier magnetic field to geomagnetic field has been a difficult problem for a long time,which influences on the deviation of navigation compass and the error of geomagnetic measurement. To increase the geomagnetic measuring accuracy required for the geomagnetic matching localization,the strategy to eliminate the effect of connatural and induced magnetic fields of carrier on the geomagnetic measuring accuracy is investigated. The magnetic-dipole's magnetic field distributing theory is used to deduce the magnetic composition in the position of the sensor installed on the carrier. A geomagnetic measurement model is established by using the measuring data with the ideal sensor. Considering the magnetic disturbance of carrier and the error of sensor,a geomagnetic measuring compensation model is built. This model can be used to compensate the errors of carrier magnetic field and magnetic sensor in any case and its parameters have clear or specific physical meaning. The experimented results show that the model has higher geomagnetic measuring accuracy than that of others.

地磁感应电流多学科交叉研究进展

地磁感应电流(geomagnetically induced currents,GIC)是指地球变化磁场在地球表面导体中产生的感应电流,可对电网、油气管道、高铁等人造基础设施造成严重破坏,包括电力系统失效、通信干扰和电子设备损坏等,影响其稳定运行和功能。研究GIC的意义在于深入理解其产生机理及影响因素,为制定相应的预防和应对策略提供科学依据。论文在深入总结GIC研究进展的基础上,详细阐述了GIC的产生机理及影响因素,包括宇宙空间、地球环境和电力系统对GIC的影响;概述了GIC的研究现状,分别从空间物理、地球物理和电气工程领域对GIC进行了综合评述;进而详细介绍了GIC估算的步骤,包括地磁场数据与建模、地电场和导体中GIC的计算;并重点分析了不同地球物理参数对GIC估算结果的影响以及互相之间的差异;最后,对GIC研究面临的挑战、地球物理在相关问题解决中的潜在贡献以及研究未来进行展望。

结合构造应力场探究地磁转换函数异常

变化的磁场是联系区域应力场和孕震区地球物理环境信息的天然媒介,而地磁短周期转换函数可以反映地下电阻率等物理信息,本研究利用有界影响估计法计算喀什地磁台地磁短周期转换函数实部Ar绝对值,并使用南天山西段及西昆仑地区的震源机制解资料反演了研究区震源机制一致性参数,其时序变化代表研究区应力场的变化。结合研究区应力场变化尝试探究地磁转换函数实部Ar绝对值异常对构造应力作用的响应。结果显示,当应力作用增强后,地磁转换函数在时间上出现同步或滞后的异常变化,表明应力在不断积累增强后,地下介质电阻率发生变化,从而引起感应磁场变化,因此得出应力变化是造成局部磁异常变化的影响因素之一,验证了地震前感应磁效应现象。通过研究8次中强震前应力场与地磁场转换函数变化,发现在6次中强震前均出现震前异常变化,两者在震前的变化有较好的一致性。研究还发现喀什地磁台地磁转换函数不同周期的实部Ar绝对值对不同方位的地震响应不同,可能与震源区地下介质各向异性差异有关。

地电暴与磁暴的对比研究

为了加深地电暴与磁暴的认知,需要全面加强地电暴与磁暴之间的对比分析。通过针对地电暴与磁暴开展识别分析与统计,并全面加强地磁场与地电场数据的相关性分析,通过对相同地区不同台站的相关记录进行对比,可以在一定程度上了解地电暴与磁暴之间的差异性。结果表明,即便台站地磁场在同一磁暴中出现的变幅基本相同,但是地电场对应的测项其最大变幅则存在相对较大差异性。这说明地电暴与磁暴有着对应关系,磁暴中的地磁场水平分量将会出现明显变化,正是因为地电暴、磁暴两者之间具有强对应关系,所以要通过地电暴与磁暴的对比进行研究,可以进一步加深对于地电暴与磁暴的认知。

Tilt of the ring current during the main phases of intense geomagnetic storms

Based on the data from the SuperMAG collaboration in 2000–2014, the magnetic latitude(MLAT) location of the ring current(RC) denoted by the MLAT of the maximum horizontal magnetic disturbance during the main phase of 67 intense geomagnetic storms(Dst ≤-100 nT) are derived. The results show that the maximum horizontal magnetic disturbance does not always occur in the magnetic equator, indicating that the RC might be tilted in the latitudinal direction during these storms. Specifically, the tilt of the RC near the day-night line is affected by the direction of solar wind. When the solar wind flows southward against the magnetic equatorial plane, the RC is more likely to show a dayside-lifted tilt. When the solar wind flows northward, the pattern is opposite. Tilts of the RC near the dawn-dusk line are also found in most of these storms. The location of the RC is mainly lifted in the dusk side and declined in the dawn side for positive IMF BY, while the tilt is reversed for negative IMF BY. A possible interpretation might be the IMF BY-related twisting of the geomagnetic field. Besides, the monthly averaged MLAT of the fitted RC also varies with seasons. It is shifted to the southern hemisphere in the northern summer and to the northern hemisphere in the northern winter, which might indicate that the RC is not centered on a single plane. Such a seasonal variation might be related to the angle between the solar wind and the magnetic equatorial plane.

An analysis of interplanetary sources of geomagnetic storm during November 7-8, 1998

We analyzed the properties of the solar wind appeared during November 7–8, 1998. Results show that the spaceship ACE spotted a shock (hereinafter referred to as the first shock) at 07:33 UT, November 7. The sheath appeared from the first shock to 22:00 UT November 7. A magnetic cloud-like (MCL) was observed during the period from 22:00 UT November 7 to 11:50 UT, November 8. Another shock was observed at 04:19 UT, November 8 (the second shock). It is apparent that the second shock has entered the rear part of the MCL (MCL_2), though the former part of the MCL (MCL_1) was not affected by the second shock. The main phase of the geomagnetic storm is split into three steps for the convenience of SYM-H index analysis. Step 1 covers the period from the sudden storm commence (SSC) at 08:15 UT, November 7 to the moment of 22:44 UT, November 7. Step 2 starts from 22:44 UT, November 7 and ends at 04:51 UT, November 8. The last step runs from 04:51 UT, November 8 to 06:21 UT, November 8. Step 2 has played a key role in the main development phase of the geomagnetic storm. Analysis of the solar wind properties associated with the main phase shows that the three steps in the main phase have sheath, MCL_1, and MCL_2 as their respective interplanetary source. Specifically, the sheath is covered by the solar wind data from 07:33 UT to 22:00 UT, November 7, MCL1 by the solar wind data from 22:00 UT, November 7 to 04:19 UT November 8, and MCL_2 by the solar wind data from 04:19 UT to 05:57 UT, November 8. MCL_1 had a strong and long lasting so UTh directed magnetic field, allowing it to play a key role in the development of the main phase. MCL_2 made a much smaller contribution to the main development phase, compared with MCL_1.

中国广东电网的几次强磁暴影响事件

2001年以来,随着我国阳-淮系统等多条500 kV长距离线路的相继建成投运,江苏上河、广东岭澳等地变压器多次发现不明原因的强烈振动和噪声增大事件.本文通过对2004年11月以来、十几次磁暴地磁数据与变压器中性点实测电流数据的比较,证明了干扰事件是磁暴在电网产生的地磁感应电流(GIC)所为;其中,2004年11月7日和10日磁暴在岭澳核电站引发的GIC最大值为47A和55.8A,大于直流输电单极运行时变压器中性点的直流电流水平,因此磁暴对岭澳核电站的瞬时影响比直流输电的影响大;监测数据表明广东电网的GIC水平高于阳淮输电系统的水平.初步分析认为与电网结构和海岸效应等因素有关.目前,举世瞩目的1000 kV特高压工程已开工建设,特高压线路的单位电阻最多是500 kV的二分之一,并且线路更长、规划规模大、且变压器采用单相变压器组结构,磁暴影响问题迫切需要研究.

磁暴对我国特高压电网的影响研究

随着我国长距离输电的发展,江苏、广东等地曾多次发现磁暴在电网中产生了较大幅度的地磁感应电流(geomagnetically induced current,GIC),有可能对电网造成危害。文章通过对电网GIC监测数据和地磁数据进行分析,指出除磁暴强度外,大地电性结构、电网结构与参数也是影响GIC水平的重要因素;借助磁暴产生GIC的物理模型并根据特高压电网线路电阻小、输电距离长、采用单相变压器等特点预测未来特高压系统中的GIC干扰问题将更加严重;根据2010年我国特高压规划建立了电网的等效模型,利用典型磁暴感应出地面电场的数值初步估算了各变电站的GIC水平;最后对目前研究中有待解决的关键问题进行了总结,并结合我国国情提出了解决方案。

考虑海岸效应影响的电网地磁感应电流的计算方法

与北欧、北美国家相比,我国大陆的磁纬低,同次地磁暴的地磁扰动(geomagnetic disturbance,GMD)相对较弱,对计算中低纬GMD地电场和电网GIC提出了更高的要求。为研究海岸效应对中低纬GMD地电场和电网地磁感应电流(geomagnetically induced current,GIC)的影响,以2004年11月9日地磁暴广东肇庆地磁台的GMD秒钟数据和广东沿海地区的大地构造资料为基础,建立了岭澳核电站沿海局部地区的一维和三维大地电导率模型,计算了GMD的地电场和岭澳核电站变压器中性点的GIC。结果表明,海岸效应对电网GIC的影响很大,在评估中低纬沿海电力系统的GIC灾害风险时,应充分考虑海岸效应的作用,以及使用地磁暴的秒钟GMD数据,能够获得更准确的计算结果。

一种基于磁偶极子磁场分布理论的磁场干扰补偿方法

载体磁场对地磁场的干扰,一直是影响导航罗差、地磁测量的技术难题。为了提高适于地磁匹配定位需要的地磁测量精度,对如何消除载体固有磁场和感应磁场对地磁测量精度的影响进行了研究。应用磁偶极子磁场分布理论,推导了安装在载体上传感器所在位置的磁场组成,建立了利用理想传感器测量值计算地磁场的地磁测量模型;在分析磁场传感器测量误差的基础上,建立了综合考虑载体磁场干扰和传感器误差影响的地磁测量模型。该模型所含参数物理意义明确,可在任意姿态下实现对载体磁场和磁传感器误差进行综合补偿。实验证明,所建立的地磁测量模型具有较高的测量精度。

太阳风暴对四川500kV电网影响的评估

太阳活动引起的地磁场剧烈变化称为磁暴。近年来随着中国西电东送长距离输电的发展,江苏、广东等地发现磁暴在电网中产生了较大幅度的地磁感应电流(GIC),有可能对电网的安全运行造成一系列的危害。中国幅员广阔,地理跨越高、中纬度区域,电网规模越来越大,电网结构与运行方式也日益呈现多样化,高压、大电网的安全与稳定问题日益突出。因此,有必要对磁暴对我国电网产生的影响进行研究。结合四川电网部分超高压电网结构,建立了电网等效模型,选取典型磁暴感应出的地面电场数值,利用MATlAB仿真软件估算了四川电网中部分500 kV变电站的GIC水平。计算结果表明,在电网的终点和拐角处容易诱发较大的GIC,其数值可达数十A。因此在强磁暴发生时,四川超高压电网的GIC水平较高,可能影响电网的安全稳定运行,须引起足够的重视。

地磁暴干扰轨道电路工作的仿真计算研究

在世界范围内曾多次发生过强磁暴导致铁路轨道电路失灵的事件,而磁暴影响轨道电路工作的机理缺乏系统性的研究。根据铁路系统接地线结构,分析地磁暴侵害轨道电路的物理过程和流过接收端扼流变压器的不平衡地磁感应电流;以2004年11月9日兰州地磁台监测数据和大地电导率数据为基础,运用平面波理论,计算兰州某两个牵引变电所之间铁路的感应地电场;根据铁路信号系统的接地情况和电气结构,估算轨道电路中的GIC水平;利用Matlab/Simulink软件对97型25Hz相敏轨道电路中信号继电器的轨道线圈侧电压进行计算仿真,研究轨道电路误动的可能性。结果表明:磁暴发生时信号继电器的二元二位继电器轨道线圈电压降低、电流相位偏离理想工作值,严重时可能导致继电器误动,造成铁路信号灯闪红,解释了高纬度国家磁暴导致的轨道信号灯闪红现象。

特大地磁暴的一种行星际源:多重磁云

20 0 1年 3月 31日观测到的大的多重磁云 (Multi MC)事件造成了第 2 3周太阳峰年 (2 0 0 0～ 2 0 0 1 )最大的地磁暴 (Dst=- 387nT) .通过分析ACE飞船的观测数据 ,描述了这个多重磁云在 1AU处的磁场和等离子体特征 .并且根据SOHO和GOES卫星的观测资料 ,认证了它的太阳源 .在这次事件中 ,由于多重磁云内部异常增强的南向磁场 ,使之地磁效应变得更强 ,它大大的延长了地磁暴的持续时间 .观测结果与理论分析表明 ,多重磁云中子磁云的相互挤压使磁云内的磁场强度及其南向分量增强数倍 ,从而加强了地磁效应 .因此 ,研究认为多重磁云中子磁云之间的相互压缩是造成特大地磁暴的一种机制 .此外 ,研究发现形成多重磁云的日冕物质抛射 (CMEs)

地磁暴感应地电场的大地电性结构建模方法

探明磁暴期间地面感应电场的分布情形是正确计算地磁感应电流(GIC)和预测磁暴次生灾害影响的前提。根据电磁场唯一性定理,从求解磁暴感应地电场的角度出发,提出了一种复杂大地电导率结构的建模方法;该方法的特点是只建大地导体区模型,通过模型的边界条件反映地磁场的变化情况及感应地电流在地下的流通情形。采用有限元法求解了典型地电结构下的磁暴感应地电场,通过对比数值方法和解析方法求得的地面电场结果,验证了建模方法的可靠性。进一步采用该方法研究了无法解析求解的复杂地电结构的磁暴感应地电场问题,建模思路和方法为评估磁暴和GIC的管网效应提供了分析工具。

新疆2020年规划电网地磁感应电流的分布规律及敏感性分析

地磁扰动会在高压电网中诱发地磁感应电流(geomagnetically induced currents,GIC)。在相同感应地电场的作用下,高电压等级输电线路的GIC较大,准确计算超高压电网的GIC具有重要意义。以我国新疆2020年规划电网为例,只考虑750k V电压等级,建立了电网的GIC计算模型,分析了均匀地电场作用下规划电网中GIC的分布规律和方向敏感性,计算并分析了电网电阻参数对GIC的影响。利用2004年11月7日至8日的磁暴监测数据,评估了强磁暴作用下电网的GIC水平。计算结果表明,电网拓扑结构、感应地电场方向及电网参数对线路及变电站GIC影响较大,在1V/km的均匀场作用下,且末、布尔津等变电站会出现超过200A的GIC,个别线路GIC超过300A。输电线路电阻变化对GIC影响程度远大于变压器绕组电阻和接地电阻的影响程度。GIC与磁暴期间磁场变化率具有时间一致性,与所选事件强度相当的磁暴作用下,变电站和线路GIC最高可达96A和184A。