CEDAR: Data-driven Modeling of the Global Equatorial Electrojet Variability

地球中低纬电离层存在着各种复杂的现象，这些现象是由于在地球磁场的影响下等离子体和中性物质的耦合动力学而产生的。此外，该区域还暴露在不断变化的地面和空间天气条件下，造成高度依赖于经度的相当大的逐日变化。该项目将使用一种全面的数据驱动的建模方法，以弥合我们在了解白天观测到的大规模低至中纬度电动力学现象的纵向和逐日变异性来源方面的差距，重点是赤道电喷流(EEJ)。该项目的结果可能有助于我们更好地描述近地空间环境中的等离子体结构，这是预测影响通信、导航和定位系统的等离子体不规则性和无线电波闪烁的关键。该项目将有助于扩大科罗拉多州立大学博尔德分校一名研究生和通过博尔德太阳能联盟REU方案招聘的三名本科生的教育和培训经验。数据驱动建模方法的开发将由四维集合变分公式指导，该公式是为NCAR热层电离层电动力学一般环流模型(TIEGCM)建立的变分方法和集合方法的混合。该方法利用了三维发电机模型的能力，它可以描述地面和低地球轨道(LEO)的磁扰动以及由风力发电机和高纬电离层对流电场驱动的三维电离层电流。具体的科学问题包括：·观测到的电磁场日变化的原因是什么？地磁场的几何形状和大小以及源自地球表面纵向不对称源的大气波在多大程度上控制着它的纵向相关性？·日变化与赤道等离子体漂移、赤道电离异常(EIA)以及赤道反电喷流(CEJ)和太阳静止电流(SQ)的变化有什么联系？将被同化的主要观测数据包括地面磁强计网络的磁场、Spot测量的LEO磁场以及从COSMIC-2和ICON飞行任务获得的电子密度和等离子体漂移测量结果。分析结果将与地面观测网络对等离子体漂移、等离子体密度和中性风的独立观测结果进行比较和验证，这些观测网络包括非相干和相干散射雷达、电离层探空仪、法布里-珀罗涉仪和全球导航卫星系统接收器以及ICON的中性风。该奖项反映了NSF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。

The Earth's low- and mid-latitude ionosphere hosts a variety of complex phenomena resulting from the coupled dynamics of plasma and neutral species under the influence of Earth’s magnetic field. This region is furthermore exposed to constantly varying conditions of both terrestrial and space weather, giving rise to considerable day-to-day variability that is highly dependent on longitudes. This project will use a comprehensive data-driven modeling approach to close the gap in our understanding of the origins of the observed longitudinal and day-to-day variability of daytime large-scale low- to mid-latitude electrodynamics phenomena with a focus on equatorial electrojet (EEJ). The outcome of this project will likely help us to better characterize the plasma structure in the near-Earth space environment, which is key to the forecasting of plasma irregularity and radio wave scintillation that affect communication, navigation, and positioning systems. The project will serve to broaden the education and training experiences of one graduate student at CU-Boulder and three undergraduate students recruited through the Boulder Solar Alliance REU program.The development of the data-driven modeling approach will be guided by a four-dimensional ensemble variational formulation, which is a hybrid of the variational and ensemble approach being built for the NCAR Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM). The approach takes advantage of the capabilities of the 3-D Electrodynamo model which can specify ground and low-Earth-orbit (LEO) magnetic perturbations and 3D ionospheric currents driven by wind dynamo and high-latitude ionospheric convection electric fields. Specific science questions addressed include: • What are the causes of the observed day-to-day variability of EEJ?; To what extent is its longitudinal dependence controlled by the geometry and magnitude of geomagnetic fields, and by the atmospheric waves originating from longitudinal asymmetric sources on the Earth's surface?• What is the connection of the EEJ day-to-day variability to the variability of equatorial plasma drifts, equatorial ionization anomaly (EIA), as well as equatorial counter electrojet (CEJ) and solar quiet (Sq) currents? The primary observational data that will be assimilated includes magnetic fields from a network of ground-based magnetometers, LEO magnetic fields measured by Swarm and electron density and plasma drift measurements obtained from COSMIC-2 and ICON missions. Analysis results will be compared and verified against independent observations of plasma drifts, plasma densities and neutral winds from ground-based observational networks, including incoherent and coherent scatter radars, ionosondes, Fabry-Perot interferometers, and Global Navigation Satellite System receivers as well as neutral winds from ICON.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.