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带电粒子的家园，称为等离子体。这些场和等离子体的变化可被称为“空间天气”，这些空间天气事件可能以多种方式严重影响人类部署的各种技术网络，包括干扰GPS技术和造成大规模停电。极地地区的地磁亚暴是日常空间天气事件，通常使用极光电射流指数进行识别和研究，这些指数是使用地面地磁场变化测量编制的。然而，虽然AE指数存在于北方半球，但没有为南半球开发这样的指数。根本没有足够的土地来放置和间隔适当的地磁仪器。然而，这是重要的，因为在北方和南方极地区域之间存在半球间不对称。换句话说，两个半球并不完全相同，因此不能假定在北方极光带进行的亚暴观测与在南极地区进行的研究是一致的。由于亚暴研究中的半球间不对称性也往往无法得到评估，该奖项将通过调查潜在的替代方法来确定南极亚暴，从而解决南极地区的数据差距。Pi 1B波是一种自然的超低频（ULF）波，其特征在于Pi 1范围内的宽带突发（1 - 40秒周期）。亚暴的发生与晚上到午夜后的Pi 1B波有很好的相关性，在地球空间文献中建议Pi 1B波可以用来监测极地亚暴的发展。该奖项将使用现有的，公开的地面磁力计数据和现场卫星测量的组合来识别和比较亚暴爆发和Pi 1B波。这项研究将解决以下突出的科学问题：（1）Pi 1B波是否是与亚暴爆发相关的极光电急流增强的代理？（2）如果是，与现有的基于AE和其他地磁指数的替代指标相比，Pi 1B替代指标如何？什么是物理机制，可以解释之间的联系Pi 1B波和亚暴爆发。这个奖项反映了NSF的法定使命，并已通过使用基金会的知识价值和更广泛的影响审查标准进行评估，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.