TIMED/GUVI observed thermospheric column ∑O/N2 depletion in both hemispheres in March 2017.

The National Aeronautics and Space Administration Global-scale observations of the Limb and Disk (GOLD) mission observed a unique structure of thermospheric column density ratio of O to N2 (∑O/N2) during a geomagnetic storm on day of year (DOY) 130 (May 10) to DOY 132 in 2019.

We conduct observational and modeling studies of thermospheric composition responses to weak geomagnetic activity (non-geomagnetic storms). We found that the thermospheric O and N 2 column density ratio (∑O/N 2 ) in part of the Northern Hemisphere measured by