CEDAR: Impacts of Lower Atmosphere Forcing on the Mesosphere-lower Thermosphere and Ionosphere During September Equinox Transition

该奖项支持基于对卫星数据的分析进行的调查，所选择的关键参数是等离子体密度、氧成分和中间层较低的热层温度。这项调查的目的是了解如何解释9月春分期间电离层总电子含量(TEC)中观察到的短期变化是由于低层大气区域和高层大气区域之间的波耦合造成的。这些TEC变化可以被描述为电离层天气，它是由100至350公里区域的大尺度低层大气波与电离层等离子体耦合所支持的几个耗散过程的结果。这一奖项将研究的关键思想是基于这样一个事实，即从低层大气区域向上传播的大尺度波在平分期达到最大。通常情况下，平流层的风会阻止这些波达到如此高的高度。然而，9月的春分是指平流层风的方向发生逆转，冬季向东，夏季向西。在春分期间，这些平流层风很弱，因此大尺度波通过中层大气区成为可能。这项调查将把9月份赤道研究计算的100至350公里区域的氧成分、温度和等离子体密度的模拟结果与卫星在同一时期对这些量的测量结果进行比较。一名本科生将通过大气研究和科学的重大机会(SOARS)计划参与拟议的研究活动。高考学生的参与将有助于加强历史上代表性不足的群体对大气科学的参与。这项研究将通过更好地了解电离层中的短期、日常变化，从而进一步造福社会。由于电离层对通信和导航信号的影响，了解这种变化至关重要。模式研究将使用最新开发的最先进的全大气数据同化模式(WACCMX)对等离子体密度进行数值模拟。将数据同化纳入WACCMX将代表第一个包含数据同化能力的全面电离层和热层的全大气模式，使人们能够对特定事件期间的上下大气耦合有新的见解。通过使用数据同化全大气模式，数值模拟可以直接与观测值进行比较。这一能力将被用来诊断导致观察到的变异性的机制。提案目标的实现将有助于全面提高对高层大气变异性的了解，利用9月春分转换作为一个典型的简化案例研究，从高层大气动力学的总体范围得出结论。这种简化是由于反转期间平流层风减弱的结果。不再需要详细了解平流层风，从而增强了评估和测量模拟高层大气动力学中正在进行的其他物理过程的模拟能力的能力。

This award supports the investigation based upon the analysis of satellite data with plasma density, oxygen composition, and mesosphere lower thermosphere temperatures being the key parameters selected. The goal of this investigation is to understand how the short-term variability that is observed in the ionosphere total electron content (TEC) during the September equinox may be explained as a result of the wave coupling between the lower and upper atmosphere regions. These TEC variations can be characterized as ionospheric weather that occur as a result of several dissipative processes that are supported by the coupling of large scale lower atmosphere waves to the ionospheric plasma of the region between 100 to 350 km. The key idea that would be studied in this award is based upon the fact that the transmission of large scale waves upward from the lower atmosphere region maximizes during the equinoctial period. Normally, the stratospheric winds would block these waves from reaching such high heights. However, the September equinox is when the direction of stratospheric winds reverses direction being eastward during winter and westward during the summer. During the equinox, these stratospheric winds are weak and then transmission of the large scale waves through the middle atmosphere region becomes possible. The investigation will compare modeled results for the oxygen composition, temperature, and plasma densities in the region of 100 to 350 km computed for the September equinoctial study to the satellite measurements of these quantities for this same period. An undergraduate student will be involved in the proposed research activities through the Significant Opportunities in Atmospheric Research and Science (SOARS) program. The involvement of a SOARS student will serve to enhance participation of historically under-represented groups in the atmospheric sciences. The research will further benefit society through an improved understanding of short-term, day-to-day, variability in the ionosphere. Understanding this variability is critical due to the impact of the ionosphere on communication and navigation signals. The modeling research would use numerical simulations of the plasma densities using a newly-developed, state-of-the-art whole atmosphere data assimilation model (WACCMX). Incorporation of data assimilation in WACCMX will represent the first whole atmosphere model with a comprehensive ionosphere and thermosphere to include the data assimilation capability, enabling new insights into lower-upper atmosphere coupling during specific events. By employing a data assimilation whole atmosphere model, the numerical simulations can be directly compared with the observations. This capability will be used to diagnose the mechanisms responsible for the observed variability. The realization of the proposal objectives will result in an overall improved understanding of the upper atmosphere variability that occurs using the September equinox transition as a representative simplified case study drawn from the overall range of upper atmosphere dynamics. This simplification is a result of the weakness of stratospheric winds during the reversal period. The elimination of the need to know in detail the stratospheric winds thus enhances the ability to assess and measure the modeling capability to simulate the other physical processes ongoing in upper atmosphere dynamics.