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Numerical Simulations of High‐Frequency Gravity Wave Propagation Through Fine Structures in the Mesosphere
Author(s) -
Mixa Tyler,
Fritts David,
Lund Thomas,
Laughman Brian,
Wang Ling,
Kantha Lakshmi
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd029746
Subject(s) - physics , thermosphere , amplitude , gravity wave , mesosphere , atmosphere (unit) , dissipation , instability , momentum (technical analysis) , atmospheric sciences , gravitational wave , computational physics , mechanics , geophysics , meteorology , ionosphere , stratosphere , astrophysics , optics , finance , economics , thermodynamics
An anelastic numerical model is used to study the influences of fine structure (FS) in the wind and stability profiles on gravity wave (GW) propagation in the Mesosphere and Lower Thermosphere (MLT). Large amplitude GWs interacting with FS, that is, thin regions of enhanced wind and stability, evolve very differently depending on the precise vorticity source and sink terms for small‐scale motions induced by the FS gradients. The resulting small‐scale dynamics are deterministic, promoting local instabilities, dissipation, and momentum deposition at locations and orientations determined by the initial FS. The resulting momentum depositions yield significant changes to the background wind structure, having scales and amplitudes comparable to the effects of large‐scale features in the ambient atmosphere. The deterministic nature of the large‐scale impacts further suggests that they can be estimated without fully resolving the underlying instability dynamics. Given the significant amplitudes and ubiquitous occurrence of FS throughout the atmosphere, the influences of these important and diverse flow evolutions merit inclusion in broader modeling efforts.