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

剩余环流是确定观测到的地球中高层大气成分和温度的经向和垂直分布的全球尺度基础。在众所周知的夏季到冬季的中间层和热层环流中，观测到的示踪剂分布表明在低层热层存在反向残余环流。然而，对驱动低层热层冬-夏环流的动力学进行深入研究的工作很少。本研究将利用中尺度解析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多尺度过程的理解，并改进模型中成分和等离子体密度的表示，从而有助于我们对多步骤垂直耦合机制的理解。一名研究生将参与并支持该项目，该工作将成为博士论文的一部分。该项目将利用大气综合模拟系统（SIMA）框架中的高分辨率全大气群落气候模式扩展（高分辨率WACCM-X），它可以捕获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。模式分辨波动量强迫，包括行星波、潮汐和重力波，是本研究的主要焦点。第二个目标是研究在地磁平静时期环流如何影响热层成分结构。将进行力项分析，以检验驱动热层中O/N2季节和纬度变化的潜在机制。利用中尺度解析全大气模式可以详细检查多尺度物理过程和相互作用如何影响热层成分。该奖项反映了美国国家科学基金会的法定使命，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.