Localized dynamic pressure pulses in the magnetosheath, or jets, have been a popular topic for discussion in recent decades. Studies show that they can propagate through the magnetosheath and impact the magnetopause, possibly showing up as geoeffective elements at ground level. However, questions still remain on how geoeffective they can be. Previous studies have been limited to case studies during few days and with only a handful of events. In this study we have found 65 cases of impacting jets using observations from the Multiscale Magnetospheric mission during 2015–2017. We examine their geoeffectiveness using ground-based magnetometers (GMAGs). From our statistics we find that GMAGs observe responses as fluctuations in the geomagnetic field with amplitudes of 34 nT, frequencies of 1.9 mHz, and damping times of 370 s. Further, the parallel length and the maximum dynamic pressure of the jet dictate the amplitude of the observed GMAG response. Longer and higher pressure jets inducing larger amplitude responses in GMAG horizontal components. The median time required for the signal to be detected by GMAGs is 190 s. We also examine if jets can be harmful for human infrastructure and cannot exclude that such events could exist.

中文翻译：

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地基磁力计对撞击磁鞘射流的响应

近几十年来，磁鞘或射流中的局部动态压力脉冲一直是讨论的热门话题。研究表明，它们可以通过磁鞘传播并影响磁层顶，可能在地面上表现为地质效应元素。然而，关于它们的地理效益如何仍然存在问题。以前的研究仅限于几天内的案例研究，并且只有少数事件。在这项研究中，我们使用 2015-2017 年多尺度磁层任务的观测发现了 65 起撞击喷流的案例。我们使用地基磁力计 (GMAG) 检查它们的地球有效性。从我们的统计数据中，我们发现 GMAG 观察到地磁场波动的响应，幅度为 34 nT，频率为 1.9 mHz，阻尼时间为 370 s。更远，射流的平行长度和最大动态压力决定了观察到的 GMAG 响应的幅度。更长和更高的压力射流在 GMAG 水平分量中引起更大的振幅响应。GMAG 检测到信号所需的中位时间为 190 秒。我们还研究了喷气式飞机是否会对人类基础设施有害，并且不能排除此类事件可能存在。