CEDAR Postdoc: Numerical Modeling of Mesospheric Bores, Nonlinear Ducted Waves, and Interpretation of Observations in the Middle Atmosphere

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)This project focuses on modeling studies of mesospheric bores. These wave features occur in the upper mesosphere and lower thermosphere and are identified as a sharp wave front with a large horizontal extent (on the order of 500 km) followed by a train of wave crests. Mesospheric bores were first observed in 1993. Since then, there have been many additional observations but limited detailed understanding. This project will quantitatively assess the dynamics and characteristics of mesospheric bores, including the environments that support them, the forcings that give rise to them, and their impacts on the atmosphere. The effort has two main components: (1) extend a current numerical model already developed to encompass more complicated forcings and environments typical of the mesosphere and lower thermosphere; (2) model observed airglow data for which concurrent lidar and radar measurements describe the thermal and wind environments. For task 1, the proposed model extensions will simulate more realistic background conditions for the bores along with the responses of various types of bore structures to these conditions. The second task will use airglow, radar, and lidar observations to provide information on the background thermal structure of the atmosphere and on how bores propagate through it. The numerical studies will improve quantitative understanding of bore dynamics and determine how the existing theories might be expanded or amended to apply in realistic environments. Applications to observations will also define how observations can best quantify the bore dynamics as well as related ducting phenomena. The broader impacts of the project concern the implications for better understanding and quantification of energy and momentum transport and deposition in the mesosphere and lower thermosphere, which impacts the mean flow and global circulation models. An improved understanding of the nonlinear dynamics of mesospheric bores is also relevant to other dynamically similar phenomena, both in the lower atmosphere and in various engineering applications. The project will support a new researcher in his first research effort after completion of the Ph.D.