Characteristics of Temperature and Density Structures in the Equatorial Thermosphere Simulated by a Whole Atmosphere GCM
Numerical simulations of the thermospheric temperature and mass density variations have been performed with a whole atmosphere general circulation model (GCM) which includes all the atmospheric regions: troposphere, stratosphere, mesosphere, and thermosphere. The GCM simulations represent hour-to-hour variations of the thermosphere due to effects from the lower atmosphere. The GCM also reproduces some characteristics of the thermospheric temperature and density structures: e.g., the midnight temperature maximum (MTM) and midnight density maximum (MDM) in the equatorial upper thermosphere. The MTMs and MDMs simulated here have the maximum amplitudes of 73 K and 19%, respectively, which are consistent with previous observations. The MTMs and MDMs simulated by the GCM also vary from hour to hour. The amplitude and location of the MTM depend on UT or longitude. In the dayside of the low-latitude region, the double-hump structure of the mass density is also seen in the GCM results. The lower atmospheric effects on the thermosphere would be important for generation of the mass density structure.
KeywordsGeneral Circulation Model General Circulation Model Simulation Atmosphere General Circulation Model Constant Pressure Surface Champ Observation
This work was supported in part by Grant-in-Aid for Scientific Research C (20540435) and Scientific Research on Innovative Areas (20200047), and the Global COE program “Global Education and Research Center for Earth and Planetary Dynamics” at Tohoku University by the Ministry of Education, Science, Sports and Culture, Japan. A part of this work was also supported by the joint research program of the Solar-Terrestrial Environment Laboratory, Nagoya University.
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