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Seasonal Variation of Thermospheric Composition Observed by NASA GOLD
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  • Liying Qian,
  • Quan Gan,
  • Wenbin Wang,
  • Xuguang Cai,
  • Richard W Eastes,
  • Jia Yue
Liying Qian
National Center for Atmospheric Research (UCAR)

Corresponding Author:[email protected]

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Quan Gan
Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder
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Wenbin Wang
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Xuguang Cai
U of colorado, Boulder
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Richard W Eastes
Laboratory for Atmospheric and Space Physics
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Jia Yue
Goddard Space Flight Center
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We examine characteristics of the seasonal variation of thermospheric composition using column number density ratio ∑O/N2 observed by the NASA Global Observations of Limb and Disk (GOLD) mission from low-mid to mid-high latitudes. We found that the ∑O/N2 seasonal variation is hemispherically asymmetric: in the southern hemisphere, it exhibits the well-known annual and seminal pattern, with highs near the equinoxes, and primary and secondary lows near the solstices. In the northern hemisphere, it is dominated by an annual variation, with a minor semiannual component with the highs shifting towards the wintertime. We also found that the durations of the December and June solstice seasons in terms of ∑O/N2 are highly variable with longitude. Our hypothesis is that ion-neutral collisional heating in the equatorial ionization anomaly region, ion drag, and auroral Joule heating play substantial roles in this longitudinal dependency. Finally, the rate of change in ∑O/N2 from one solstice season to the other is dependent on latitude, with more dramatic changes at higher latitudes.