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arXiv 2402.03261astro-ph.SRastro-ph.IMphysics.space-ph
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磁暴主相扰动的特征与发展（Dst ≤ -50 nT）

Characteristics and development of the main phase disturbance in geomagnetic storms (Dst $\le$ -50 nT)

Osman M. Ahmed, Badruudin Zaheer Ahmad, Moncef Derouich

备注：
Accepted for publication in Advances in Space Research
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AI总结：

本研究分析1995-2022年三个太阳活动周的地磁暴，发现主相发展主要由行星际磁场南向分量驱动，Dst峰值滞后Bz 1-4小时，且Dst峰值与SSC振幅正相关、与SSC持续时间负相关，并提出了与地磁活动指数最佳相关的太阳风参数组合。

摘要：

我们展示了选自三个太阳活动周、时间跨度为1995年至2022年的地磁暴（GSs）。我们研究了扰动风暴时（Dst）振幅范围从Dst = -64 nT到Dst = -422 nT的暴主相的发展。为了确定主要影响地磁暴主相发展的太阳风（SW）参数，这些参数最能描述太阳风-磁层耦合，我们根据主相持续时间将所选地磁暴分为四组。分别对每组选定的地磁指数、太阳风等离子体和磁场参数及其导数进行了叠加历元分析。为此，地磁暴主相发展的动力学主要由行星际驱动磁场的南向分量（-Bz）引导。已确定Bz和Dst的峰值之间存在时间差异。因此，Dst相对于Bz延迟1-4小时，这对空间天气预测至关重要。Dst的峰值与风暴急始（SSC）的振幅有直接关系，与SSC的持续时间有反比关系。还获得了地磁暴期间三个指数（Dst、AE和ap）峰值之间的相互关系。发现Dst与ap的关系比与AE的关系更密切。为了确定与地磁活动指数最匹配的太阳风参数，我们使用了各个地磁指数峰值与太阳风等离子体和场参数及其导数之间的线性相关性。一个涉及速度和IMF（v$^{4/3}$Bz）的电场相关函数，当与粘性项（$ρ^{1/2}$）耦合时，与地磁暴强度（Dst$_{min}$或$Δ$Dst）以及暴期间（ap$_{max}$）和（AE$_{max}$）的幅度非常相关。然而，一个相关函数（v$^{4/3}$B$ρ^{1/2}$）在暴期间对AE$_{max}$峰值的表示略好。

英文摘要：

We present geomagnetic storms (GSs) selected from three solar cycles, spanning the years 1995 to 2022. We studied the development of the main phase of storms within disturbance storm time (Dst) amplitudes ranging from Dst =-64 nT to Dst=- 422 nT. In order to determine the solar wind (SW) parameters that mainly influence the main phase development of a GS, which can best describe the SW-magnetosphere coupling, we divided our selected GSs into four groups based on main phase duration. Superposed epoch analysis was performed on the selected geomagnetic indices, SW plasma and field parameters, and their derivatives separately for each group. To that end, the dynamics of GS main phase development is mainly guided by interplanetary driver magnetic field southward component, (-Bz). It has been determined that there is a temporal difference between the peak values of Bz and Dst. As a result, Dst is delayed from Bz by 1-4 hours, which is crucial for space weather forecasting. The peak of Dst has a direct relationship with the amplitude of storm sudden commencement (SSC) and an inverse relationship with the duration of SSC. The inter-relationship between the peaks of the three indices (Dst, AE, and ap) during GS, is also obtained. Dst is found to be more closely related to ap than AE. To determine the best fit SW parameter to the geomagnetic activity indices, we used a linear correlation between the peak values of individual geomagnetic indices and SW plasma and field parameters and their derivatives. An electric field related function involving speed and IMF (v$^{4/3}$Bz) when coupled with a viscous term ($ρ^{1/2}$) correlates very well with the intensity of the GS (Dst$ _{min} $ or $ Δ$Dst) and the magnitude of (ap$_{max}$) and (AE$_{max}$) during storms. However, a related function (v$^{4/3}$B$ρ^{1/2}$) represents slightly better the peak of AE$_{max}$ during the storms.

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