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的研究，其中等离子体密度、氧成分和中间层较低的热层温度是选定的关键参数。本次调查的目的是了解如何在9月春分期间观测到的电离层总电子含量（TEC）的短期变化可能被解释为低层和高层大气区域之间的波耦合的结果。这些TEC变化可以被描述为电离层天气，其发生是由大规模低层大气波与100至350公里之间区域的电离层等离子体的耦合所支持的几个耗散过程的结果。该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输的大尺度波在春分期间达到最大值。通常情况下，平流层的风会阻止这些波到达如此高的高度。然而，在九月的春分点，平流层风的方向会发生逆转，冬季为东，夏季为向西。春分时，平流层风较弱，大尺度波通过中层大气的传播成为可能。调查将比较模拟结果的氧成分，温度和等离子体密度在100至350公里的区域计算的9月春分研究卫星测量这些数量为同一时期。一名本科生将通过大气研究和科学（SOARS）计划的重大机会参与拟议的研究活动。SOARS学生的参与将有助于提高历史上代表性不足的群体在大气科学中的参与。这项研究将通过更好地了解电离层的短期、日常变化，进一步造福社会。由于电离层对通信和导航信号的影响，了解这种可变性至关重要。建模研究将使用新开发的、最先进的全大气数据同化模型（WACCMX）对等离子体密度进行数值模拟。 将数据同化纳入WACCMX将是第一个具有综合电离层和热层的全大气模型，包括数据同化能力，从而能够对特定事件期间的低层-高层大气耦合有新的认识。通过采用资料同化的全大气模式，数值模拟可以直接与观测进行比较。 这一能力将用于诊断导致观察到的变异性的机制。该提案各项目标的实现将导致对高层大气变化的全面了解，这种变化是利用9月春分点过渡作为从高层大气动态的总体范围中得出的代表性简化案例研究而发生的。 这种简化是由于平流层风在逆转期间很弱。因此，消除了详细了解平流层风的必要性，提高了评估和衡量模拟高层大气动态中其他物理过程的建模能力。

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.