Effects of small-scale gravity waves of lower atmospheric origin on the mean fields and the migrating diurnal tide in the middle atmosphere and thermosphere
Abstract
Gravity waves (GWs) of lower atmospheric origin influence the dynamical and thermal structure of the thermosphere even beyond the middle atmosphere. Using a general circulation model extending from the lower atmosphere to the upper thermosphere and incorporating the whole atmosphere spectral nonlinear gravity wave parameterization of Yiğit et al. (2008), GW propagation, dissipation, and the resulting effects on the mean fields and the diurnal migrating tide are investigated during equinox. GWs significantly change the mean circulation (by up to ±40 m/s) and cool the thermosphere (up to -90 K) above the turbopause (105 km). GWs impact the diurnal tide at almost all latitudes in the mesosphere and lower thermosphere and, primarily, at middle- and high-latitudes in the upper thermosphere, increasing/decreasing the tidal amplitude depending on the latitude in a qualitative agreement with previous observations. GW effects in the thermosphere should be accounted for in GCMs in order to better capture diurnal tidal features.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSA31C..08Y
- Keywords:
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- 3334 Middle atmosphere dynamics;
- ATMOSPHERIC PROCESSESDE: 3369 Thermospheric dynamics;
- ATMOSPHERIC PROCESSESDE: 3384 Acoustic-gravity waves;
- ATMOSPHERIC PROCESSESDE: 4490 Turbulence;
- NONLINEAR GEOPHYSICS