Study of Mutual Diffusion Effects in the Upper Atmosphere and Thermospheric Gravity Wave Processes

这项研究是一个为期三年的努力，以开发一个独特的二元气体全波模型，将模拟多组分气体，并纳入所有相关的物理过程，如科里奥利力，平均风，涡流和分子扩散的热量和动量，反射。 这种详细的处理是必要的，因为热层是一种扩散分离的多组分气体，其中各个物种处于静态平衡，并根据其各自的尺度高度分层。该模型将是第一个现实的理论治疗这些过程中的一些，并将被应用到各种科学课题，如热层中的声重力波的耗散和随后的影响，这种波耗散的平均状态。 将计算感热、动量和质量的波通量以及非等温大气中的波反射，并将使用等效重力波方法进行潮汐模拟。 将开发一个对两个物种求和的辅助模型，用于评估全波模型中的多物种效应。 考虑到一个以上的物种的存在是必要的，因为波耗散由于物种之间的碰撞是一个重要的热源的热层。 通过热层传播的重力波使气体脱离静态平衡，并使单个气体以不同的振幅和相位振荡，而相互扩散试图减轻这些差异并恢复扩散平衡。 热大气层中的单个气体可能经历波动，并且单个气体相对于彼此所表现出的波的振幅和相位提供了波周期的重要特征，在大气的该区域中对此知之甚少。 波效应是成分、波周期和波长、以及动量和热碰撞耦合、由涡流和分子粘性和热传导引起的波耗散以及反射的复杂函数。 一个模型，包括所有这些过程同时是一个基本的要求，以进一步了解重力波的传播，耗散，和波的热层特性，并量化知之甚少的热层与低层大气源的波强迫。 将使用详细模型分析已发表的卫星观测结果，以测试模型并推断波浪周期。 该项目的目标是量化高层大气各区域的变化和耦合。 它还解决了波的性质的基本扩散过程。 这项研究将对高层大气科学领域产生重大影响，对目前未列入全球大气环流模型的波过程作出重大贡献。 计划向社区提供新模型，以帮助促进发现和理解。 一名全日制研究生和一名半日制本科生将参与这项研究。

This investigation is a three year effort to develop a unique binary gas full-wave model that will simulate a multi-constituent gas and incorporate all relevant physical processes such as the Coriolis force, mean winds, eddy and molecular diffusion of heat and momentum, and reflection. This detailed treatment is necessary since the thermosphere is a diffusively separated multi-constituent gas in which individual species are in static equilibrium and are stratified according to their individual scale heights. The model will be the first realistic theoretical treatment of some of these processes and will be applied to various science topics such as the dissipation of acoustic gravity waves in the thermosphere and the subsequent effects of this wave dissipation on the mean state. Wave fluxes of sensible heat, momentum, and mass, and wave reflection in a non-isothermal atmosphere will be calculated, and tidal simulations will be produced using the equivalent gravity wave approach. An auxiliary model that sums over two species will be developed and used to assess multi-species effects in the full-wave model. Accounting for the presence of more than one species is necessary since wave dissipation due to collisions between species is an important heat source for the thermosphere. Gravity waves that propagate through the thermosphere drive the gases out of static equilibrium and cause individual gases to oscillate with different amplitudes and phases while mutual diffusion attempts to mitigate these differences and restore diffusive equilibrium. The individual gases in the thermosphere may undergo wave motion and the amplitudes and phases of the waves exhibited by the individual gases relative to each other provide an important signature of wave periods, about which little is known in this region of the atmosphere. Wave effects are a complex function of composition, wave period and wavelength, as well as momentum and thermal collisional coupling, wave dissipation by eddy and molecular viscosity and thermal conduction, and reflection. A model that includes all these processes simultaneously is a fundamental requirement to furthering our understanding of gravity wave propagation, dissipation, and the wave characteristics in the thermosphere and to quantify poorly understood wave forcing of the thermosphere associated with lower atmospheric sources. Published satellite observations will be analyzed using the detailed model to test the model and to infer wave periods. The project addresses the goal of quantifying variations in and coupling between regions of the upper atmosphere. It also addresses fundamental diffusion processes in wave properties. The research will impact the field of upper atmospheric science by contributing substantially to wave processes currently not included in global general circulation models. It is planned to provide the new model to the community to help promote discovery and understanding. A full time graduate student will be involved in the research as well as a half-time undergraduate student.