Postdoctoral Fellowship: OPP-PRF: Investigating Polar Geomagnetic Signatures Associated with Substorm Onset to Address Data Gaps in Southern Hemisphere Space Weather Research

太空通常被认为是真空，但它是各种电磁场和被称为等离子体的带电粒子的家园。这些领域和等离子体的变化可以被称为“空间天气”，这些空间天气事件可能会在几个方面严重影响人类部署的各种技术网络，包括干扰GPS技术和造成大范围电力停电。极地地区的地磁亚暴是每日的空间天气事件，通常使用极光电喷流指数进行识别和研究，而极光电喷流指数是利用地面地磁场变化测量编制的。然而，虽然北半球有声发射指数，但没有为南半球制定这样的指数。根本没有足够的土地来放置适当的地磁仪器。然而，这一点很重要，因为南北两极地区之间存在半球间的不对称。换句话说，这两个半球并不完全相同，因此不能假设从北极地区观测到的亚风暴与在南极地区所做的研究是一致的。由于亚暴研究中的半球间不对称性也不能经常被评估，该奖项将通过调查识别南极亚暴的潜在替代方法来解决南极区的数据差距。Pi1B波是一种以Pi1范围(1-40秒周期)的宽带爆发为特征的自然超低频(ULF)波。亚暴开始与晚间到午夜后的Pi1B波有很好的相关性，地球空间文献中建议可以用Pi1B波来监测极地亚暴的发展。该奖项将使用现有的、可公开获得的地面磁力仪数据和现场卫星测量数据来识别和比较亚暴初始波和Pi1B波。这项研究将解决以下悬而未决的科学问题：(1)Pi1B波是与亚暴爆发;相关的极光电喷流强化的替代指标吗？(2)如果是，Pi1B替代指标与基于声发射和其他地磁指数;的现有替代指标相比如何；以及(3)可以解释Pi1B波和亚暴爆发之间联系的物理机制是什么。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Space is often considered a vacuum, but it is home of various electromagnetic fields and charged particles called plasma. Variations in these fields and plasma can be called “space weather”, and these space weather events may severely impact various human-deployed technological networks in several ways, including interfering with GPS technologies and causing vast electric power blackouts. Geomagnetic substorms in polar regions are daily space weather events and these are typically identified and studied using Auroral Electrojet (AE) indices, which are compiled using ground-based geomagnetic field variation measurements. However, while AE indices exist in the Northern Hemisphere, there are no such indices developed for the Southern Hemisphere. There simply is not enough land to have appropriately placed and spaced geomagnetic instruments. However, this is important because there are interhemispheric asymmetries between the northern and southern polar regions. In other words, the two hemispheres are not identical, so it cannot be assumed that substorm observations from the northern auroral zone are compatible with research done in the southern polar areas. As the interhemispheric asymmetries in substorm research are also not often able to be evaluated, this award will be addressing the southern polar regions’ data gap by investigating potential alternate methods to identify southern polar substorms. The Pi1B waves are a type of natural Ultra Low Frequency (ULF) waves characterized by broadband bursts in the Pi1 range (1 – 40 second periods). Substorm onsets are well correlated with Pi1B waves in the evening to post-midnight sectors, and it was suggested in the geospace literature that Pi1B waves could be used to monitor polar substorms development. This award will use a mix of existing, publicly available ground-based magnetometer data and in-situ satellite measurements to identify and compare both the substorm onsets and Pi1B waves. This research will address the following outstanding science questions: (1) Are Pi1B waves a proxy for Auroral Electrojet intensification associated with substorm onset; (2) If so, how does the Pi1B proxy compare with existing proxies based on the AE and other geomagnetic indices; and (3) What are physical mechanisms that can explain connections between the Pi1B waves and substorm onsets.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.