Comparison of geosynchronous energetic particle flux responses to solar wind dynamic pressure enhancements and substorms
Comparison of geosynchronous energetic particle flux responses to solar wind dynamic pressure enhancements and substorms
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DOI：
10.1029/2005ja011091
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发表时间：
2005-09
影响因子：
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通讯作者：
Dabin Lee;L. Lyons;G. Reeves
中科院分区：
文献类型：
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作者：
Dabin Lee;L. Lyons;G. Reeves
[1] 地球同步高能粒子通量用于研究太阳风动压 Pdyn 增强引起的粒子扰动与亚暴引起的粒子扰动之间的异同。扰动也可以根据国际货币基金组织的状况来区分。首先，对于不强向南的 IMF 条件（弱向南或向北的 IMF），我们发现 Pdyn 增强引起的磁层压缩通常会导致所有能量通道的粒子通量同时增加。这种增加是地球周围的全球性的，但通常首先发生在白天，然后在几分钟内传播到夜晚。我们还发现，磁层压缩有时会导致某些 MLT 处至少一个能量通道的通量减少或没有通量变化，我们将其归因于恒定绝热不变量下的径向轮廓的形状。然而，当 IMF 不强烈南移时，我们在 Pdyn 增强事件中没有发现类似亚暴注入的证据。在长时间强烈南向 IMF 后，由 IMF 变化引起的亚暴会导致对流电场减小，并且与 Pdyn 变化无关，产生的通量扰动与不太强南向 IMF 条件下的典型亚暴通量扰动非常相似。然而，在更宽的方位角区域发现了无色散注入前沿，有时质子会延伸到下午晚些时候。我们发现，在长期稳定、强烈南向 IMF 条件下，Pdyn 增强会导致双模态扰动。磁层压缩引起的扰动可以清楚地识别出来，并且主要在白天看到，而与当前楔形形成相关的亚暴注入则在夜间看到。在这两种物种中都可以看到日侧压缩效应，但在质子通量中比在电子通量中更容易识别。在这两个物种中也可以看到类似亚暴的注入特征，但通常在电子通量中更为明显。在这里研究的事件中，白天的压缩扰动先于夜间的亚暴风注入几分钟。
[1] Geosynchronous energetic particle fluxes are used to examine the differences and similarities between the particle disturbances due to an enhancement in solar wind dynamic pressure Pdyn and those caused by substorms. Disturbances are also distinguished by IMF conditions. First, for not strongly southward IMF conditions (weakly southward or northward IMF), we find that the magnetospheric compression by a Pdyn enhancement usually causes particle fluxes to increase simultaneously at all energy channels. The increase is global around the Earth, but it usually occurs first on the dayside and then propagates to the nightside within a few minutes. We also find that a magnetospheric compression sometimes leads to a flux decrease or no flux change for at least one energy channel at some MLTs, which we attribute to the shape of radial profiles at constant adiabatic invariants. However, we find no evidence for substorm-like injections in our Pdyn enhancement events when the IMF is not strongly southward. Following prolonged strongly southward IMF, substorms caused by IMF changes that lead to convection electric field reduction and are not associated with a Pdyn change generate flux disturbances that are quite similar to typical substorm flux disturbances for less strongly southward IMF conditions. However, the dispersionless injection front is found over a much wider azimuthal region, sometimes extending to the late afternoonside for protons. We find that under prolonged steady, strongly southward IMF conditions, a Pdyn enhancement leads to a two-mode type disturbance. The disturbance due to magnetospheric compression can be clearly identified and is seen primarily on the dayside, and a substorm-like injection associated with current wedge formation is seen on the nightside. The dayside compression effect is seen in both species, but is often more easily identified in the proton fluxes than in the electron fluxes. The substorm-like injection feature is also seen in both species but is usually more evident in the electron fluxes. In the events studied here, the dayside compression disturbance precedes the substorm-like injection on the nightside by a few minutes.