Presentation Information
[PEM10-11]Impact of the lower thermospheric winter-to-summer residual circulation on thermospheric composition★Invited Papers
*Liying Qian1, Jia Yue2,3 (1.University Corporation for Atmospheric Research, 2.Center for Atmospheric Science, Hampton University, 3.ESSIC, University of Maryland College Park)
Keywords:
Thermosphere Circulation,Thermosphere Composition,Ionosphere Winter Anomaly
Gravity wave forcing near the mesopause drives a summer-to-winter residual circulation in the mesosphere and a reversed, lower thermospheric winter-to-summer residual circulation. We conducted modeling studies to investigate how this lower thermospheric residual circulation impact thermospheric composition (O/N2). We found that the upwelling associated with the residual circulation significantly decreases O/N2 in winter and the downwelling in summer slightly increases O/N2. Consequently, the residual circulation reduces the summer-to-winter latitudinal gradient of O/N2, which causes the simulated latitudinal gradient of O/N2 to be more consistent with observations. The smaller summer-to-winter latitudinal gradient of O/N2 would decrease the ionosphere winter anomaly in model simulations, which would bring the simulated winter anomaly into better agreement with ionospheric observations. The lower thermospheric residual circulation may be a process that has been largely ignored but is very important to the summer-to-winter latitudinal gradients, as well as annual/semiannual variations in the thermosphere and ionosphere.