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

高层大气与热层重力波过程中相互扩散效应的研究

• 批准号: 0639293
• 负责人: Michael Hickey
• 金额: $ 25.81万
• 依托单位: Embry-Riddle Aeronautical University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0639293&HistoricalAwards=false
• 关键词: Study; Mutual; Diffusion; Effects; Upper

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.

这项研究是一项为期三年的工作，旨在发展一个独特的二元气体全波模型，该模型将模拟多组分气体，并包括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、热和动量的扩散以及反射。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，其中单个物种处于静态平衡状态，并根据其各自的尺度高度分层。该模型将是对其中一些过程的第一个现实的理论处理，并将被应用于各种科学课题，如热层中声波重力波的耗散，以及这种波耗散对平均状态的后续影响。将计算感热、动量和质量的波通量，以及在非等温大气中的波反射，并将使用等效重力波方法产生潮汐模拟。将开发一个超过两个物种总和的辅助模式，并用于评估全波模式中的多物种效应。考虑到不止一个物种的存在是必要的，因为物种之间的碰撞引起的波耗散是热层的一个重要热源。通过热层传播的重力波使气体脱离静态平衡，导致单个气体以不同的幅度和相位振荡，而相互扩散试图缓解这些差异并恢复扩散平衡。热层中的单个气体可能会发生波动，各个气体相对于彼此的波动的幅度和相位提供了一个重要的波动周期的标志，而在大气的这一区域，人们对此知之甚少。波的效应是组成、波周期和波长的复杂函数，以及动量和热碰撞耦合、涡流和分子粘性的波耗散、热传导和反射。一个同时包含所有这些过程的模式是加深我们对重力波在热层中的传播、耗散和波特征的理解，以及量化与低层大气源有关的热层波强迫的基本要求。发布的卫星观测将使用详细的模型进行分析，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区域的变化和相互之间的耦合。它还讨论了波特性中的基本扩散过程。这项研究将对目前尚未包括在全球大气环流模式中的波动过程作出重大贡献，从而影响高层大气科学领域。它计划向社会提供新的模式，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。