Swarm, FORMOSAT-7/COSMIC-2, and ICON ionospheric observations during the annular solar eclipse on 21 June 202

Abstract

On 21 June 2020, an annular solar eclipse pass over Africa, Europe, and Asia.  When the moon’s shadow sweeps, the solar radiation is blocked out and leads to weak photochemical effects and other variations on the ionosphere.  The ion/electron temperature, density, and the ion vertical drift velocity measured by multi-satellites have been estimated and analyzed.  EFI (Electric Field Instrument) onboard Swarm with a circular orbit of 88° inclination and 530 km altitude provides the data of electron temperature and density.  IVM (ion velocity meter) onboard FORMOSAT-7/COSMIC-2 (F7/C2) with a circular orbit of 24° inclination and 550 km altitude supplies information on the ion temperature, density, and ion vertical drift velocity.  IVM onboard Ionospheric Connection Explorer (ICON) with a circular orbit of 27° inclination and 579 km altitude offers the same parameters as F7/C2.  On the event day, a total of 9 paths of those satellites passed through the greatest eclipse path, 6 from F7/C2, 2 from ICON, and 1 from Swarm.  Referencing one-month data of each satellite path, both ion and electron temperature decrease about 500K after the maximum contact.  Three of the four solar eclipse signatures in the ion density are observed, including pre-ascensions, major depressions, and sunset ascensions.  Moreover, the ion drift velocity tends to be downward around the maximum contact.  Detailed results will be presented and discussed.