Long-term variations in the neutral gas composition of the thermosphere over Norilsk (2003–2013)

Abstract

Seasonal variations in relative values of the main gas components of the thermosphere [O]/[N2] and [O2]/[O] were obtained at the station Norilsk during the period 2003–2013. Estimates were made using a technique we developed and data from the Norilsk digisonde (69° N, 88° E) for heights below the ionospheric F1-layer peak height under quiet and disturbed geomagnetic conditions in different seasons. We established that the [O2]/[O] ratio under quiet and disturbed geomagnetic conditions in all seasons by the end of 2013 decreased from 10 to 20 % relative to the values of 2003. The [O]/[N2] ratio for the same conditions increased to 17 %.

Keywords

• thermospheric gas components
• geomagnetic disturbances
• seasonal variations