Ionospheric disturbance dynamo is one of the main processes that causes perturbations in the upper atmosphere during a magnetic storm. We present a new method, based on the least square fitting, for estimation of the magnetic signatures associated with ionospheric disturbance currents. Using a wavelet semblance analysis, the durations of disturbance dynamo electric fields have been investigated at three longitudinal sectors. For that we have analyzed the disturbance dynamo (D_dyn) for 19 magnetic storms. It has been found that during CME generated storms magnetic signature of D_dyn may be observed—depending on strength of the storm as well as on the duration of interplanetary magnetic field (IMF) Bz southward—in one, two or all three longitudes. The Oscillatory behavior of IMF Bz during the high-speed solar wind streams (HSSWs) generates D_dyn globally and the corresponding effects are observed at all low latitude magnetic observatories. In this regard, the Joule heating estimation shows that CME and HSSWs generated storms have very different patterns. The D_dyn duration is found to be maximum for the storms occurring during equinox season. Moreover, the HSSWs events are more likely to cause—because of the oscillatory IMF Bz—long lasting D_dyn as compared to CME generated counterpart. This study presents a detailed analysis of disturbance dynamo as affected by longitudinal and seasonal variations. In this regard the difference in magnetic signatures, of CME and HSSWs originated storms, have been highlighted.

中文翻译：

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CME 和 HSSW 产生的风暴的电离层扰动发电机的磁特征

电离层扰动发电机是磁暴期间引起高层大气扰动的主要过程之一。我们提出了一种基于最小二乘拟合的新方法，用于估计与电离层干扰电流相关的磁特征。使用小波外观分析，已经在三个纵向扇区研究了扰动发电机电场的持续时间。为此，我们分析了19 次磁暴的扰动发电机 ( D _dyn )。已经发现，在 CME 产生的风暴磁特征中，D _dyn根据风暴的强度以及行星际磁场 (IMF) Bz 向南的持续时间，可能会在一个、两个或所有三个经度上观察到。IMF Bz 在高速太阳风流 (HSSW) 期间的振荡行为在全球范围内产生D _dyn，并且在所有低纬度磁观测站都观察到了相应的影响。在这方面，焦耳加热估计表明 CME 和 HSSW 产生的风暴具有非常不同的模式。发现在春分季节发生的风暴的D _dyn持续时间最大。此外，由于 IMF Bz 的振荡，HSSW 事件更有可能导致持久的D _dyn与 CME 生成的对应物相比。本研究详细分析了受纵向和季节性变化影响的扰动发电机。在这方面，CME 和 HSSW 起源的风暴的磁特征差异已得到强调。