Statistical Comparison of Auroras in Northern and Southern Hemispheres

极光显示是太阳-地球连接的光学表现，研究极光可以了解这种连接及其耦合。由于地球物理学的限制（南半球约2/3的极光在海洋上方），缺乏关于南半球极光的信息。目前对极光的认识主要是基于对北方的观测。这妨碍了对磁层-电离层作为一个整体系统的充分理解。随着基于卫星的粒子和光学成像的出现以及在南极地区进行的更多观测，越来越多的证据表明，极光并不总是半球对称和/或共轭的，特别是在某些条件和某些类型的极光下。因此，从两个半球研究极光可以提供更多的关于极地风-磁层-电离层耦合的信息。这种方法是必不可少的，因为过去的研究要么依赖于来自单个半球的全球极光图像，要么依赖于来自两个半球的组合粒子数据。预期结果将通过约翰霍普金斯大学应用物理实验室极光粒子和图像小组的网站提供，该网站向空间物理学界提供各种极光数据和模型，包括OVATION Prime。此外，预期的结果可用于更新OVATION Prime极光模式。该计划的目标是研究南北大尺度极光强度的半球对称性和不对称性，以提高目前对太阳风-磁层-电离层耦合的认识。具体而言，以下问题将作为科学目标加以解决：（1）行星际磁场（IMF）和极光的南北不对称性之间是否存在关系？(2)南极极光对阳光的反应是否与北方极光相似？（3）地磁场与极光强度之间是否存在关系？该项目包括分析美国航天局的TIMED/GUVI从两个半球获得的远紫外极光图像。它将使用（1）大量（~6年的价值）FUV波段的近全球极光图像，具有前所未有的光谱和空间分辨率，不仅来自北方半球，而且来自鲜为人知的南半球，以及（2）对某些波长下的图像进行定量反演，可以揭示这些沉淀粒子的特征，如它们的能量和功率，大气层上层的存款。这种方法已经在最近的案例研究中进行了测试，涉及GUVI数据，并证明了这些反演的准确性和实用性。该奖项反映了NSF的法定使命，并被认为是值得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的支持。

Auroral displays are an optical manifestation of the Sun-Earth connection, and studying the aurora provides understanding of this connection and their coupling. Owing to geophysical constraints (~2/3 of aurora in the southern hemisphere are above the ocean), there is a lack of information on the southern hemisphere aurora. Current knowledge of the aurora is based primarily on observations made in the Northern Hemisphere. This has prevented full understanding of the magnetosphere-ionosphere as a whole system. With the advent of satellite-based particle and optical imaging and more observations made in the southern polar regions, there is mounting evidence suggesting that auroras are not always hemispherically symmetric and/or conjugate, especially under certain conditions and certain types of aurora. Therefore, studying the aurora from both hemispheres can provide much more information about the polar wind-magnetosphere-ionosphere coupling than any single hemisphere does. This type of approach is essential because past studies have either relied on global auroral images from a single hemisphere or on combined particle data from both hemispheres. The expected results will be made available through the JHU/APL (Johns Hopkins University Applied Physics Laboratory) Auroral Particles and Images Team web site, which serves up a variety of auroral data and models, including the OVATION Prime, to the space physics community. Furthermore, the expected result can be used to update the OVATION Prime auroral model.The goal of this proposal is to study hemispheric symmetries and asymmetries of the large-scale north and south auroral intensity to improve current knowledge of the solar wind-magnetosphere-ionosphere coupling. Specifically, the following questions are to be addressed as science objectives: (1) Are there relationships between the IMF (Interplanetary Magnetic Field) and the north-south asymmetry of the aurora? (2) Does the southern aurora respond to sunlight in a similar manner as the northern aurora does? and (3) Is there a relationship between the geomagnetic field and auroral intensity? This project consists of analyzing FUV (far-ultraviolet) auroral images acquired by NASA's TIMED/GUVI from both hemispheres. It will be carried out using (1) a large number (~6 years' worth) of near-global auroral images in the FUV band with unprecedented spectral and spatial resolution not only from the Northern Hemisphere but also from the lesser-known Southern Hemisphere and (2) the quantitative inversion of images made at certain wavelengths which can reveal characteristics of these precipitating particles such as their energy and the power they deposit in the upper atmosphere. This method has been tested in recent case studies involving GUVI data and have demonstrated the accuracy and utility of these inversions.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.