This research explores the fundamental dynamics of gravity waves and their interaction with moist convection and baroclinic waves. It will characterize the source, dynamics and impacts of the mesoscale gravity waves generated in the moist baroclinic jet-front systems through utilizing high-resolution simulations of idealized moist baroclinic waves along with analyzing real-case modeling and aircraft observations during past field campaigns. The major objectives of the research are following. (1) Investigate the characteristics, source, propagation and dynamics of gravity waves simulated in high-resolution simulations of idealized moist baroclinic waves, examine the similarities and differences of wave initiation and propagation between simulations with varying intensity of moist convection, understand the coupling and interactions of gravity waves with small-scale moist convection and large-scale background baroclinic waves, and assess the momentum/energy fluxes from these gravity waves and their impacts on the large-scale circulation. (2) Explore the role of gravity waves and balance adjustment in the upscale error energy transfer from small-scale convection to largescale baroclinic waves and the impacts on mesoscale predictability of moist baroclinic jet-front systems under both idealized experiments and real-data events. (3) Characterize the source, propagation, dynamics and impacts of mesoscale gravity waves in the extratropical uppertropospheric lower-stratospheric region through analyzing high-resolution aircraft measurements and numerical simulations during the 2008 Stratosphere-Troposphere Analyses of Regional Transport Experiment (START08), and quantitatively compare the momentum and energy fluxes estimated from aircraft and satellite observations with those calculated from model simulations.

Intellectual Merit: Gravity waves are ubiquitous in the atmosphere and play a fundamental role in a wide variety of atmospheric processes that have important implications for tropospheric weather, stratospheric dynamics, ozone chemistry and the general circulation. They can transfer significant amounts of energy and momentum, initiate and organize convection, and produce atmospheric turbulence. The momentum transport and deposition by gravity waves have significant impacts on the general circulation of the atmosphere. A better knowledge of these processes demands a complete understanding of the mechanisms by which the gravity waves are generated, together with their characteristics, distribution and variability. Building on the progress and success on dry dynamics of gravity waves achieved under previous NSF supports, the ultimate goal of this project is to understand the dynamics and impacts of the mesoscale gravity waves generated by the tropospheric baroclinic jet-front systems and their interactions with moist convection.

Broader Impacts: Better understanding of mesoscale gravity waves and their interaction with moist processes may lead to better understanding of the dynamics and improved forecasts of convective triggers and modulation as well as the associated severe weather. Better understanding of flow imbalance and mesoscale gravity waves may provide guidance on mesoscale data assimilation and mesoscale predictability. Better understanding of gravity wave processes may also lead to better parameterization of the energy and momentum transport between the troposphere and stratosphere by non-topographic and non-convective mesoscale gravity waves. This project will fund and train two graduate students. It will also foster research collaborations between the university and several leading research institutions.

National Science Foundation (NSF)
Division of Atmospheric and Geospace Sciences (AGS)
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A. Gannet Hallar
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Pennsylvania State University
University Park
United States
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