Collaborative Research: CEDAR--Quantifying Ion Drifts in the Mid-latitude Ionosphere and Their Coupling to the Neutral Atmosphere

大气区域耦合、能量学和动力学（CEDAR）项目是一个基础广泛、社区指导的高层大气研究项目。它旨在了解大气区域在区域和全球尺度上的耦合、能量学、化学和动力学方面的行为，从大气中层向上通过电离的上层大气进入外层空间。中纬度电离层是两极和赤道活跃电离层之间的中介层，但对它的研究还不是很彻底。这项由德克萨斯大学达拉斯分校、弗吉尼亚理工大学和科罗拉多大学参与的合作雪松奖旨在开发第一个电离层电场分布的安静时间经验模型，以填补必要的基础真相，从而产生对电离层全球动态的真正理解。这项研究工作将利用15年来空军国防气象空间等离子体（DMSP）对中纬度电离层离子纬向流动速度的测量来构建中纬度电离层静时电场的经验模型。该数据集将由中纬度superdam站点获得的离子漂移数据补充。这个数据库将提供给外部用户，因此将成为电离层社区的宝贵资源。在完成平静时间模型的开发之后，将把风暴时间的观测结果与基于应用新平静时间模型的预测结果进行比较。确定的差异将在CTIP（耦合热层电离层等离子体层）-RCM模式运行的指导和背景下进行分析，以了解导致观测到的变化相对于所建立的基线模式的潜在物理机制，量化风暴时间干扰的大小和程度，最后，量化中纬度离子漂移到中性大气的耦合以及极地和赤道地区之间的能量转移。最后，利用近二十年的DMSP数据来理解和开发经验模型，这是CEDAR航空计划的一个基本挑战，即量化中纬度电场的基线模型。因此，作为太阳相位、地磁活动以及与低层大气和磁层区域的动力耦合的函数的变率问题可以得到更仔细的评估。所取得的结果将对电离层和热层建模界产生极大的兴趣和用途，也与“了解空间-大气相互作用区域（SAIR）的基本特性；确定确定SAIR的全球行为、演变和对日地系统影响的相互关联的过程”。该项目的主要目标是量化电离层相对于TIMED和SDO航天器对太阳极紫外线（EUV）辐射的直接光谱分离测量的响应。这种方法是对以前基于代理的研究的巨大改进。C/NOFS和DMSP航天器将在一定高度提供相应的电离层参数测量。该数据集跨越超过一个太阳周期，允许使用先进的统计分析技术，并将与SAMI-2模型一起使用，以解决与理解电离层对太阳EUV变率的响应相关的突出科学问题。有待研究的有趣问题包括高层大气中中性组分和电离组分响应的相对重要性和相互作用。

The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program is a broad-based, community-guided, upper atmospheric research program. It is aimed at understanding the behavior of atmospheric regions from the middle atmosphere upward through the ionized upper layers of the atmosphere and into outer space in terms of coupling, energetics, chemistry, and dynamics on regional and global scales. The mid-latitude ionosphere serves as the intermediary between the active ionospheres of the polar and equatorial regions, but it has not been studied very thoroughly. This Collaborative CEDAR award involving University of Texas at Dallas, Virginia Tech University, and the University of Colorado is aimed at developing the first quiet-time empirical model of the ionosphere electric field distribution to fill in the necessary ground truth needed to produce a true understanding of the global dynamics of the ionosphere. The research effort would use 15 years of Air Force Defense Meteorological Space Plasma (DMSP) measurements of ion zonal flow speeds in the mid-latitude ionosphere to construct an empirical model of mid-latitude ionospheric quiet-time electric fields. This data set would be supplemented by ion drift data obtained from the mid-latitude SuperDARN sites. This database would be made available to outside users, and thus, would be a valuable ionospheric community resource. Following the completion of the development of the quiet time model, observations from storm times will be compared to predictions based upon application of the new quiet time model. The determined differences would be analyzed within the guidance and context of the CTIP (Coupled thermosphere ionosphere plasmasphere)-RCM model runs to understand the underlying physical mechanisms causing the observed variability relative to the baseline model established, to quantify the magnitude and extent of storm-time disturbances, and finally, to quantify the coupling of the mid-latitude ion drifts to the neutral atmosphere and the transfer of energy between the polar and equatorial regions. Finally, making use of nearly two decades of DMSP data to understand and develop empirical models goes to the heart of one of the fundamental challenges of the CEDAR Aeronomy program, which is to quantify a baseline model of mid-latitude electric fields. Consequently, the question of variability as a function of solar phase, geomagnetic activity, and dynamical coupling to the lower atmosphere and to the magnetosphere regions can be more carefully assessed. The results achieved would be of great interest and use to the ionosphere and thermospheric modeling community and also relevant to the CEDAR mission of "understanding the fundamental properties of the space-atmosphere interaction region (SAIR); identify the interconnected processes that define the SAIR's global behavior, evolution, and influence on the Sun-Earth system". The main goal of this project is to quantify the response of the ionosphere relative to direct, spectrally separated measurements of solar extreme ultraviolet (EUV) radiation from the TIMED and SDO spacecraft. This approach constitutes an immense improvement over previous studies based on proxies. The C/NOFS and DMSP spacecraft at a range of altitudes will provide corresponding measurements of ionospheric parameters. This dataset, spanning more than a solar cycle, allows for the use of advanced statistical analysis techniques and will be used together with the SAMI-2 model to address outstanding science questions related to understanding the ionospheric response to solar EUV variability. Interesting questions to be investigated include the relative importance of and interaction between the responses in the neutral and ionized components of the upper atmosphere.