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Gravity waves in the thermosphere during a sudden stratospheric warming
Author(s) -
Yiğit Erdal,
Medvedev Alexander S.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053812
Subject(s) - thermosphere , atmospheric sciences , sudden stratospheric warming , atmosphere (unit) , stratosphere , gravity wave , environmental science , atmospheric tide , mesosphere , ionosphere , atmospheric circulation , climatology , physics , gravitational wave , polar vortex , geology , geophysics , meteorology , astrophysics
We examine for the first time the propagation of gravity waves (GWs) of lower atmospheric origin to the thermosphere above the turbopause during a sudden stratospheric warming (SSW). The study is performed with the Coupled Middle Atmosphere‐Thermosphere general circulation model and the implemented spectral GW parameterization of Yiğit et al. (2008). Simulations reveal a strong modulation by SSWs of GW activity, momentum deposition rates, and the circulation feedbacks at heights up to the upper thermosphere (∼270 km). Wave‐induced root mean square wind fluctuations increase by a factor of three during the warming above the turbopause. This occurs mainly due to a reduction of filtering eastward traveling harmonics by the weaker stratospheric jet. Compared to nominal conditions, these GW harmonics propagate to higher altitudes and have a larger impact on the mean flow in the thermosphere, when they are dissipated. The evolution of stratospheric and mesospheric winds during an SSW life‐cycle creates a robust and distinctive response in GW activity and mean fields in the thermosphere above the turbopause up to 300 km.