Impact of the lower thermospheric winter-to-summer residual circulation on thermospheric composition
Abstract |
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 impacts 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. |
Year of Publication |
2017
|
Journal |
Geophysical Research Letters
|
Volume |
44
|
Number of Pages |
3971-3979
|
Date Published |
05/2017
|
URL |
http://doi.wiley.com/10.1002/2017GL073361
|
DOI |
10.1002/2017GL073361
|
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