CEDAR: Neutral wind drivers of variability in the prereversal enhancement

地球电离层是地球附近的空间区域（距离地表约90-1000公里），其中存在大量的等离子体（离子和电子）。能够预测这一空间区域的变化是很重要的，因为它影响到无线电传播、全球定位系统、超视距雷达、卫星通信和轨道重返。地球电离层的一个壮观的特征是所谓的“反转前增强”（PRE），它发生在日落时分，导致整个电离层向上移动高达100公里。在这个项目中，来自美国宇航局电离层连接探测器（ICON）航天器的新数据将用于了解哪些机制导致PRE从一天到下一天以及从一个经度到下一个经度发生变化。不同的机制以前已经在理论上预测过，但它们从未经过数据测试。本研究的结果有助于更好地预测赤道扩展F，这对通信和导航系统有不利影响。 除了科学影响外，该项目还将通过对本科生的指导，使教育和STEM劳动力培训受益。该项目包括对ICON和Jicamarca射电天文台（JRO）数据的分析。科学问题是：什么机制控制PRE的纵向和日常变化？科学的目标是确定中性风观测的特征，这些特征与PRE在不同地区和每天的强度变化相关。首先，将进行确认研究，以确保ICON等离子体漂移和PRE估计值与JRO测量值一致。接下来，PRE强度和中性风的纵向模式将被确定和比较，有和没有一个独立的电动发电机解算器的帮助。将通过比较PRE从一天到下一天的变化与风的变化来研究逐日变化。这项工作将阐明导致PRE的机制，因此将有利于未来的工作，旨在预测和模拟PRE的变化和赤道扩展F的variability.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The Earth's ionosphere is the region of space near Earth (~90-1000 km above the surface) where a significant population of plasma (ions and electrons) exists. It is important to be able to predict changes in this region of space because it affects radio propagation, GPS, over-the-horizon radar, satellite communication, and orbital re-entry. One spectacular feature of Earth's ionosphere is the so-called "pre-reversal enhancement" (PRE), which occurs at sunset and causes the entire ionosphere to move upward by up to 100 km. In this project, new data from NASA's Ionospheric Connection Explorer (ICON) spacecraft will be used to understand which mechanisms cause the PRE to change from one day to the next and from one longitude to the next. Different mechanisms have been previously predicted theoretically, but they have never before been tested with data. The results of this research could facilitate better predictions of equatorial spread F, which has deleterious effects on communication and navigation systems. In addition to the scientific impact, this project will benefit education and STEM workforce training via mentoring of undergraduate students.This project comprises an analysis of data from ICON and the Jicamarca Radio Observatory (JRO). The science question is: What mechanisms control the longitudinal and day-to-day variability of the PRE? The science objective is to determine the features of neutral wind observations that are correlated with changes in the strength of the PRE across longitudes and from day to day. First, a validation study will be performed to ensure that ICON plasma drifts and PRE estimates are consistent with JRO measurements. Next, longitudinal patterns of PRE strength and neutral winds will be determined and compared, with and without the aid of a standalone electrodynamo solver. Day-to-day variability will be studied by comparing changes in the PRE from one day to the next with changes in the wind. This work will elucidate mechanisms that cause the PRE and will therefore benefit future work that is aimed at predicting and modeling PRE variability and equatorial spread F variability.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.