Collaborative Research: CEDAR--Assimilative Analysis of Low- and Mid-latitude Ionospheric Electrodynamics

地球赤道电离层的现象与诸如中性风和温度以及等离子体密度和离子/电子温度等基本参数的垂直剖面有关，是复杂的。这种复杂性的根本原因在于在地磁场影响下运行的热层风、电导率、电场和电流的相互耦合动力学。该区域还暴露在不断变化的地面天气和空间天气条件下，这些条件加在一起产生了很大的逐日变率。该项目的目标是开发一种专门针对低纬度电动力学问题的综合数据同化方法，从而缩小我们对纵向依赖的起源及其日常变化的理解差距。该项目将通过参与这种多方面的研究方法，拓宽德克萨斯大学达拉斯分校（UTD）的研究生和科罗拉多大学博尔德分校（CU-Boulder）的博士后研究员的教育和培训经验。这位UTD的研究生将花一个夏天的时间访问科罗拉多大学博尔德分校和NCAR，接受使用数值模拟和数据同化工具的培训。这项调查与现代社会对更强大、更可靠的通信、导航和定位系统的需求高度相关。本项目要解决的具体科学问题包括：1)对观测到的白天大尺度赤道现象的日变率及其纵向和季节依赖性的原因进行定量分析；(2)地磁场的几何形状和大小以及地球表面纵向不对称源产生的大气潮汐在多大程度上控制了这种纵向依赖性。

The phenomenology of the Earth's equatorial ionosphere with respect to vertical profiles of basic parameters such as the neutral wind and temperature as well as plasma density and ion/electron temperatures is complex. The root causes of the complexity lie in the mutually coupled dynamics of thermospheric winds, conductivity, electric fields and currents operating under the influence of the geomagnetic field. This region is also exposed to the continual varying conditions of both terrestrial weather and space weather, which taken together give rise to large day-to-day variability. The project's objective is to achieve the development of a comprehensive data assimilation approach tailored specifically to the problem of low-latitude electrodynamics that would close the gap in our understanding of the origins of longitudinal dependence and its day-to-day variability. The project would broaden the education and training experiences of a graduate student at University of Texas Dallas (UTD) and a postdoctoral researcher at University of Colorado Boulder (CU-Boulder) by their participation in this multi-faceted research approach. The UTD graduate student will spend a summer visiting CU-Boulder and NCAR for training in the use of numerical modeling and data assimilation tools. The investigation is highly relevant to the need of the modern society for more powerful and reliable communication, navigation and positioning systems. Specific science questions to be addressed in this project include 1) the quantitative breakdown of the causes of the observed day-to-day variability of daytime large scale equatorial phenomena along with its longitudinal and seasonal dependency; and 2) to what extent is the longitudinal dependence controlled by the geometry and magnitude of geomagnetic fields, and by the atmospheric tides originating from longitudinal asymmetric sources on the Earth's surface.