Gravity Wave Sources and Parameterization

Northwest Research Associates, Incorporated, Seattle WA

Investigators

Abstract

Gravity waves are important atmospheric phenomena that affect atmospheric circulation, and energy and momentum transfers. A three-year program of modeling, observational analysis, and parameterization development will be conducted, focusing on the local generation and global effects of gravity waves in the atmosphere. The goals of the project are to develop a detailed understanding of the processes causing wave generation, and to study the conditions that determine whether the waves propagate upward into the upper atmosphere or remain trapped in the low atmosphere. Trapped gravity waves can affect weather, while vertically propagating waves influence the general circulation and climate on the global scale via momentum transfer and forcing of the circulation. The project uses a set of modeling tools spanning a hierarchy of complexity and includes strict observational validation. Intellectual Merit. The project seeks a deeper understanding of the processes leading to gravity wave generation and the translation of this knowledge into more realistic and better constrained parameterizations for global models. Parameterization development means capturing fundamental physical dependences and identifying key tunable parameters that scale with nonlinear or other neglected effects. The research efforts include parameterization applications in a global model to study short-term climate change effects (such as the El Nino-Southern Oscillation) on gravity wave sources and their subsequent effects on atmospheric circulation. The fundamental understanding gained from this work on the processes of gravity wave generation can provide a basis for evaluating the treatment of these processes in future global models. Broader Impacts. This research will improve the treatment of gravity wave mean-flow forcing processes in global models used for climate prediction, ozone recovery assessments, and weather forecasting. Model improvements can have obvious impacts on human society and the environment in general. In the tropics, additional broader impacts of gravity waves are related to their effect on cirrus cloud occurrence frequencies and ice particle sizes. The process-level studies of gravity waves generated by convection will allow quantification of the roles of these waves in cirrus and upper atmospheric water vapor changes. The study of gravity waves in the vicinity of convection may also impact future work on local weather forecasts and turbulence associated with breaking waves that impacts aviation. This NSF-funded research also contributes to education and research training for a postdoctoral scientist and a number of graduate students.