Observations of Gravity Wave Package Dissipation during its Upward Propagation in the Mesopause region.

Abstract:

Gravity waves have been known to deposit energy and momentum through dissipation during their upward propagation, which changes the dynamic flow and thermal structure in the lower thermosphere. For an upward propagating gravity wave packet with rich spectrum, various theoretical works and model simulations have indicated that the wave components with high frequency and larger vertical wavelength experience dissipation at higher altitude and dominate earlier stage, while the low frequency components, with short vertical wavelength, dominate during the latter part of the propagation. However, the evidences of such critical dissipation mechanism in the gravity wave packet propagation process have yet been comprehensively studied and discussed in the experimental observations. In this paper, utilizing the observations from the Na lidar, the Meteor Wind Radar (MWR) and the Advanced Mesospheric Temperature Mapper (AMTM) at Utah State University, we investigate several cases of this dynamic scenario over Logan, Utah (41.7°N, 111.8°W), to study the waves’ evolution as they are propagating upward.