RUI: Gravity Wave Effects in the Mesosphere/Lower Thermosphere (MLT) Region with a 2-D, Nonlinear, Multiple-Airglow Chemistry-Dynamics Model

The project will develop a 2-D time-dependent nonlinear chemistry-dynamics model of the mesosphere/lower thermosphere region to simulate the response of two airglow emissions to atmospheric gravity waves. Gravity waves are important because they transport energy and momentum from the lower atmosphere to the upper atmosphere, where they can deposit their energy and momentum through wave-mean flow interactions. These interactions can result in perturbations to the distributions of atmospheric species by the combined effects of chemical perturbations and vertical transport; exothermic heating variations may also be induced. In addition to gravity waves, airglow in the mesosphere/lower thermosphere region constitutes another important research topic in the atmospheric science community: variations in airglow intensity can oftentimes be used to deduce characteristics of gravity waves or other types of waves that cause the variations. The project includes both elements, gravity waves and airglow emissions, by constructing a model that includes a monochromatic gravity wave dynamics code and a chemistry code that simulates two airglow emissions: OH and the O2 atmospheric (0,1) band. The model will be used to study the following topics: 1) gravity wave effects on the OH and O2(b1) airglow emission layers in a windless atmosphere and for a constant background wind condition; 2) the airglow response to a variety of different gravity wave characteristics; 3) wave-induced secular variations of the airglow intensities and the intensity-weighted temperatures of the two airglow layers; 4) the amplitude growth factor associated with the various simulations of the airglow layers; 5) wave-induced secular variations of gas species concentrations; and 6) wave-induced exothermic heating associated with the passage of different gravity waves. Comparisons with observations will be made to test and validate the model. Undergraduate students will participate in the project by analyzing the simulated airglow emissions to determine the effects of gravity waves, co-authoring the papers describing the work, and presenting some of the results at professional meetings such as the annual CEDAR meeting. The model resulting from this research will provide a unique tool to the community.