Thermospheric Circulation Using Mesoscale-Resolving Whole Atmosphere Model and Satellite Observations

剩余环流构成了确定观测到的地球中高层大气成分和温度的纬向和垂直分布的全球尺度基础。在著名的夏季到冬季的中间层和热层环流，观测到的示踪剂分布表明，在低层热层存在一个反向的剩余环流。然而，很少有工作已经做了彻底调查的动力学驱动的低热层冬夏环流。这项研究将利用一个中尺度分辨率的全大气模式对低热层环流进行全面研究。该研究旨在增加对高层大气中多尺度过程的理解，并改善模型中成分和等离子体密度的表示，其变革方面可能有助于我们对多步垂直耦合机制的理解。本项目将利用SIMA（System for Integrated Modeling of the Atmosphere）框架下的高分辨率WACCM-X（High-resWACCM-X）全球大气社区气候模式扩展（WACCM-X），捕捉从全球尺度到中尺度过程之间的多尺度相互作用。该项目有两个目标。第一个目标是研究驱动热层剩余环流的物理过程。模型分辨的波动量强迫，包括行星波，潮汐和重力波，是本次调查的主要重点。第二个目标是研究在地磁平静期环流如何影响热层成分结构。将进行力项分析，以检查的基本机制，负责驱动的季节性和纬度变化的O/N2的热层。利用中尺度解析全大气模型，可以详细研究多尺度物理过程和相互作用如何影响热层组成。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Residual circulation forms the global-scale basis for determining the observed meridional and vertical distribution of composition and temperature in the Earth’s middle and upper atmosphere. Among the well-known summer-to-winter mesospheric and thermospheric circulations, observed tracer distribution suggests the existence of a reversed residual circulation in the lower thermosphere. However, very little work has been done to thoroughly investigate the dynamics driving the lower-thermospheric winter-to-summer circulation. This research will conduct a comprehensive study of the lower-thermospheric circulation by utilizing a mesoscale-resolving whole atmosphere model. The research aims to increase understanding of multi-scale processes in the upper atmosphere and improve the representation of compositions and plasma density in models, with transformative aspects that could contribute to our understanding of multi-step vertical coupling mechanisms. A graduate student will participate and be supported by this project, and the work will be part of the doctoral thesis.This project will utilize the high-resolution Whole Atmosphere Community Climate Model eXtended (high-res WACCM-X) in System for Integrated Modeling of the Atmosphere (SIMA) framework, which can capture multi-scale interactions among processes from global scales to mesoscale. The project has two objectives. The first objective is to examine the physical processes driving the residual circulation in the thermosphere. Model-resolved wave momentum forcing, including planetary waves, tides, and gravity waves, is the primary focus of this investigation. The second objective is to investigate how the circulation affects the thermospheric compositional structure during geomagnetically quiet times. A force term analysis will be performed to examine the underlying mechanisms responsible for driving the seasonal and latitudinal variation of O/N2 in the thermosphere. Utilizing the meso-scale resolving whole atmosphere model enables a detailed examination of how multi-scale physical processes and interactions impact thermospheric compositions.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.