{"title":"Extreme Responses of the Ionospheric Radial Currents to the Main Phase of the Super Geomagnetic Storm on 10 May 2024","authors":"Hao Xia, Hui Wang, Kedeng Zhang","doi":"10.1029/2024JA033126","DOIUrl":null,"url":null,"abstract":"<p>On 10 May 2024, a super geomagnetic storm occurred with a minimum Dst index of −412 nT. This study investigates the behavior of the ionospheric radial current (IRC) during the main phase of this storm using data from Swarm A and simulations from the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM). At dawn, the IRC exhibits distinct temporal variations: a strong outward flow of 14 nA/m<sup>2</sup> between 18:00 and 20:00 UT and an inward flow of −15 nA/m<sup>2</sup> by 24:00 UT. At dusk, the IRC starts with an inward value of −6 nA/m<sup>2</sup> and rapidly reverses to an outward flow peaking at 15 nA/m<sup>2</sup> between 22:00 and 24:00 UT. The dawn-dusk asymmetry of the IRC is primarily influenced by the merging electric field (<i>E</i><sub><i>m</i></sub>). Increasing <i>E</i><sub><i>m</i></sub> penetrates to low latitudes, establishing an eastward (dusk) or westward (dawn) electric field and enhancing the outward (dusk) or inward (dawn) IRC through meridional Hall currents. Model results indicate that the strong polarity changes in dawn IRC are linked to local disturbed zonal winds (<span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>u</mi>\n </mrow>\n <mi>y</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }u}_{y}$</annotation>\n </semantics></math>). Which are eastward at dawn and westward at other magnetic local times (MLT). The eastward/westward <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>u</mi>\n </mrow>\n <mi>y</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }u}_{y}$</annotation>\n </semantics></math> generate outward/inward F-layer dynamo currents, driving the disturbed vertical electric field (<span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>E</mi>\n </mrow>\n <mi>z</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }E}_{z}$</annotation>\n </semantics></math>) in opposite direction. The significant outward reversal of dusk ∆IRC could be attribute to the rapid enhancement of disturbed Pedersen conductivity (<span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>σ</mi>\n </mrow>\n <mi>p</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }\\sigma }_{p}$</annotation>\n </semantics></math>). Due to nonzero geomagnetic declination, eastward/westward <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>u</mi>\n </mrow>\n <mi>y</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }u}_{y}$</annotation>\n </semantics></math> corresponds to an increase/decrease in <span></span><math>\n <semantics>\n <mrow>\n <msub>\n <mrow>\n <mi>Δ</mi>\n <mi>σ</mi>\n </mrow>\n <mi>p</mi>\n </msub>\n </mrow>\n <annotation> ${{\\Delta }\\sigma }_{p}$</annotation>\n </semantics></math>.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 12","pages":""},"PeriodicalIF":2.6000,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Space Physics","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2024JA033126","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
On 10 May 2024, a super geomagnetic storm occurred with a minimum Dst index of −412 nT. This study investigates the behavior of the ionospheric radial current (IRC) during the main phase of this storm using data from Swarm A and simulations from the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM). At dawn, the IRC exhibits distinct temporal variations: a strong outward flow of 14 nA/m2 between 18:00 and 20:00 UT and an inward flow of −15 nA/m2 by 24:00 UT. At dusk, the IRC starts with an inward value of −6 nA/m2 and rapidly reverses to an outward flow peaking at 15 nA/m2 between 22:00 and 24:00 UT. The dawn-dusk asymmetry of the IRC is primarily influenced by the merging electric field (Em). Increasing Em penetrates to low latitudes, establishing an eastward (dusk) or westward (dawn) electric field and enhancing the outward (dusk) or inward (dawn) IRC through meridional Hall currents. Model results indicate that the strong polarity changes in dawn IRC are linked to local disturbed zonal winds (). Which are eastward at dawn and westward at other magnetic local times (MLT). The eastward/westward generate outward/inward F-layer dynamo currents, driving the disturbed vertical electric field () in opposite direction. The significant outward reversal of dusk ∆IRC could be attribute to the rapid enhancement of disturbed Pedersen conductivity (). Due to nonzero geomagnetic declination, eastward/westward corresponds to an increase/decrease in .
在2024年5月10日,发生了一次Dst指数最小值为- 412 nT的超级地磁风暴。本文利用Swarm a的数据和热层-电离层电动力学环流模型(TIEGCM)的模拟,研究了风暴主阶段电离层径向电流(IRC)的行为。黎明时分,IRC表现出明显的时间变化:在18:00至20:00 UT之间,向外流为14 nA/m2,在24:00 UT之前,向内流为- 15 nA/m2。黄昏时,IRC开始向内的值为- 6 nA/m2,并在22:00至24:00之间迅速逆转为向外的流量,峰值为15 nA/m2。IRC的黎明-黄昏不对称性主要受合并电场(Em)的影响。增加的电磁穿透到低纬度地区,建立向东(黄昏)或向西(黎明)的电场,并通过经向霍尔电流增强向外(黄昏)或向内(黎明)的IRC。模式结果表明,黎明IRC强烈的极性变化与局地扰动纬向风有关(Δ u y ${{\Delta }u}_{y}$)。它们在黎明时向东,在其他地磁地方时(MLT)向西。东/西Δ y ${{\Delta }u}_{y}$产生向外/向内的f层发电机电流,驱动扰动垂直电场(Δ E z ${{\Delta }E}_{z}$)向相反方向运动。黄昏∆IRC的显著向外反转可归因于扰动Pedersen电导率的快速增强(Δ σ p ${{\Delta }\sigma }_{p}$)。由于非零地磁偏角,东/西Δ y ${{\Delta }u}_{y}$对应于Δ σ p的增加/减少${{\Delta }\sigma }_{p}$。