Nighttime Exospheric Temperature Maximum During Quiet Time of Solar Minimum Period Based on Swarm Satellites

The nighttime exospheric temperature maximum is an important part of the characteristics of upper atmospheric temperature variations, which contributes to the understanding of atmospheric temperature and the improvement of the neutral atmosphere model. Previously, due to the scarcity of upper thermosphere temperature observations, studies of the nighttime exospheric temperature maximum were mainly based on single-site and joint observation of ground-based FPI stations as well as simulation studies of the phenomena and mechanisms of various neutral atmosphere models and ionospheric models. The work in this paper carries out the statistics of global and seasonal variations of the nighttime exospheric temperature maximum during solar minimum period by deriving the exospheric temperature obtained from the neutral density of the Swarm satellite accelerometer. The results show that the stronger the solar activity is, the higher the probability and intensity of the occurrence of the nighttime exospheric temperature maximum, and the higher the probability of multiple maximum peaks. When F10.7 is between 80 and 100, the temperature enhancement occurs in all four seasons and in different longitude sectors, but with differences in morphology and intensity. For F10.7 less than 80, the temperature enhancement is stronger and longer in spring and fall, and weaker in summer and winter. In addition, the presence or absence of nocturnal enhancement varies from sector to sector.