The paper investigates the strengthening of magnetospheric activity related to geosynchronous magnetopause crossings (GMCs). We make a list of GMC events using the empirical magnetopause model (Lin et al., 2010, https://doi.org/10.1029/2009ja014235) and hourly averaged OMNI data and find which solar wind and magnetospheric conditions accompany and follow the GMCs. The GMCs are mostly caused by the impact of interplanetary coronal mass ejections (ICMEs) and/or interplanetary shocks often with a strong increase in the density and a moderate increase in velocity. The average solar wind density during the first GMC hour is higher than 20 cm⁻³ in 70% cases, while the velocity is higher than 500 km/s in 56% cases. The hourly interplanetary magnetic field (IMF) B_Z is negative in 87% cases. The average over all events SMU (SML), Kp, and PC indices reach maxima (minima) in 1 h after the GMC beginning, while the delay of the minimum of the Dst index is usually 3–8 h. These average time delays do not depend on the strength of the storms and substorms. The SML (Dst) minimum is less than −500 nT (−30 nT) in the next 24 h in 95% (99%) cases, that is, the GMC events are mostly followed by magnetic storms and substorms. We compare solar wind and magnetospheric conditions for GMCs connected with ICMEs and stream interaction regions (SIRs). Our study confirms that the ICME-related events are characterized by stronger ring current and auroral activity than the SIR-related events. The difference might be explained by the different behavior of the solar wind velocity.

中文翻译：

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地球同步磁层顶穿越及其与磁暴和亚暴的关系

该论文研究了与地球同步磁层顶穿越 (GMC) 相关的磁层活动的增强。我们使用经验磁层顶模型（Lin 等人，2010，https://doi.org/10.1029/2009ja014235）和每小时平均的 OMNI 数据列出 GMC 事件，并找出哪些太阳风和磁层条件伴随并跟随 GMC . GMCs 主要是由行星际日冕物质抛射 (ICME) 和/或行星际冲击的影响引起的，通常密度急剧增加，速度适度增加。在第一个 GMC 小时内，平均太阳风密度在 70% 的情况下高于 20 cm ^-3，而在 56% 的情况下速度高于 500 km/s。每小时行星际磁场 (IMF) B _Z在 87% 的情况下为阴性。所有事件 SMU (SML)、Kp 和 PC 指数的平均值在 GMC 开始后 1 小时内达到最大值（最小值），而 Dst 指数最小值的延迟通常为 3-8 小时。这些平均时间延迟不取决于风暴和亚风暴的强度。在 95% (99%) 的情况下，在接下来的 24 小时内 SML (Dst) 最小值小于 -500 nT (-30 nT)，即 GMC 事件之后主要是磁暴和亚暴。我们比较了与 ICME 和流相互作用区 (SIR) 相关的 GMC 的太阳风和磁层条件。我们的研究证实，ICME 相关事件的特征是比 SIR 相关事件更强的环流和极光活动。这种差异可能是由太阳风速度的不同行为来解释的。