TY - JOUR
T1 - Impact of gravity wave drag on the thermospheric circulation
T2 - Implementation of a nonlinear gravity wave parameterization in a whole-atmosphere model
AU - Miyoshi, Yasunobu
AU - Yiğit, Erdal
N1 - Funding Information:
Japan (grant no. 15H03733); the JSPS, Japan (grant no. 18H04447); and the National Science Foundation, USA (grant no. AGS 1452137).
Funding Information:
Acknowledgements. The GFD Dennou library was used to produce the figures. The numerical simulation was performed using the computer system at the Research Institute for Information Technology of Kyushu University and at the National Institute of Information and Communication Technology, Japan. Erdal Yig˘it was partially funded by the National Science Foundation (NSF) grant AGS 1452137.
Publisher Copyright:
© 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
PY - 2019/10/17
Y1 - 2019/10/17
N2 - To investigate the effects of the gravity wave (GW) drag on the general circulation in the thermosphere, a nonlinear GW parameterization that estimates the GW drag in the whole-atmosphere system is implemented in a whole-atmosphere general circulation model (GCM). Comparing the simulation results obtained with the whole-atmosphere scheme with the ones obtained with a conventional linear scheme, we study the GW effects on the thermospheric dynamics for solstice conditions. The GW drag significantly decelerates the mean zonal wind in the thermosphere. The GWs attenuate the migrating semidiurnal solar-tide (SW2) amplitude in the lower thermosphere and modify the latitudinal structure of the SW2 above a 150 km height. The SW2 simulated by the GCM based on the nonlinear whole-atmosphere scheme agrees well with the observed SW2. The GW drag in the lower thermosphere has zonal wavenumber 2 and semidiurnal variation, while the GW drag above a 150 km height is enhanced in high latitude. The GW drag in the thermosphere is a significant dynamical factor and plays an important role in the momentum budget of the thermosphere. Therefore, a GW parameterization accounting for thermospheric processes is essential for coarse-grid whole-atmosphere GCMs in order to more realistically simulate the atmosphere-ionosphere system.
AB - To investigate the effects of the gravity wave (GW) drag on the general circulation in the thermosphere, a nonlinear GW parameterization that estimates the GW drag in the whole-atmosphere system is implemented in a whole-atmosphere general circulation model (GCM). Comparing the simulation results obtained with the whole-atmosphere scheme with the ones obtained with a conventional linear scheme, we study the GW effects on the thermospheric dynamics for solstice conditions. The GW drag significantly decelerates the mean zonal wind in the thermosphere. The GWs attenuate the migrating semidiurnal solar-tide (SW2) amplitude in the lower thermosphere and modify the latitudinal structure of the SW2 above a 150 km height. The SW2 simulated by the GCM based on the nonlinear whole-atmosphere scheme agrees well with the observed SW2. The GW drag in the lower thermosphere has zonal wavenumber 2 and semidiurnal variation, while the GW drag above a 150 km height is enhanced in high latitude. The GW drag in the thermosphere is a significant dynamical factor and plays an important role in the momentum budget of the thermosphere. Therefore, a GW parameterization accounting for thermospheric processes is essential for coarse-grid whole-atmosphere GCMs in order to more realistically simulate the atmosphere-ionosphere system.
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U2 - 10.5194/angeo-37-955-2019
DO - 10.5194/angeo-37-955-2019
M3 - Article
AN - SCOPUS:85073679131
SN - 0992-7689
VL - 37
SP - 955
EP - 969
JO - Annales Geophysicae
JF - Annales Geophysicae
IS - 5
ER -