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Some wave characteristics of the middle atmosphere simulated in a general circulation model extending from the surface to 100 km
Author(s) -
Hunt B. G.
Publication year - 1984
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711046313
Subject(s) - barotropic fluid , baroclinity , gravity wave , thermosphere , wavenumber , internal wave , atmosphere (unit) , tropopause , amplitude , atmospheric sciences , dissipation , physics , geophysics , gravitational wave , atmospheric wave , instability , atmospheric circulation , climatology , geology , mechanics , meteorology , stratosphere , ionosphere , astrophysics , quantum mechanics , optics , thermodynamics
A zonal Fourier analysis has been made of selected meteorological fields produced in a general circulation model extending up to 100 km. The model was set up for non‐diurnal, fixed January conditions, included land‐sea contrast but omitted mountains. The results largely conform to the predictions of the Charney‐Drazin criterion, at least in that only low wavenumbers in the winter are able to penetrate to the lower thermosphere. Higher wavenumbers are rapidly attenuated above the tropopause, but, very interestingly, they are regenerated with increasing amplitudes from 50 to 100 km. The occurrence of such small‐scale features is consistent with deduced dissipation rates and aeronomical characteristics in the lower thermosphere. The energy source for these small waves appears to be partially attributable to barotropic energy transfer, responding to a wave spectrum excited by baroclinic instability and internal gravity waves. A further unquantifiable energy source is associated with upwards‐propagating gravity waves. The combination of baroclinic and inertial instabilities together with barotropic processes, upwards‐propagating planetary and gravity waves indicates the wealth of dynamical processes occurring in the middle atmosphere and reproduced in the model.