FORMOSAT-7/COSMIC-2 Observations of Ionospheric Disturbances before the 14 November 2019 M7.1 Indonesia Earthquake

FORMOSAT-7/COSMIC-2 (F7/C2), with the mission orbit of 550 km altitude, 24-deg inclination, and a period of 97 minutes, has been observing the ionosphere since June of 2019. Tri-GNSS Radio occultation System (TGRS), Ion Velocity Meter (IVM), and RF beacon onboard six small satellites of F7/C2 are employed to observe the plasma structure and dynamics in the equatorial/low-latitude ionosphere. F7/C2 TGRS sounds ionospheric RO (radio occultation) electron density profiles, while F7/C2 IVM probes the ion density, ion temperature, and ion velocity at the satellite altitude. The F7/C2 electron density profiles, ion density, ion temperature, and ion velocity, as well as the global ionospheric map (GIM) of the total electron content (TEC) derived from global ground-based GPS receivers are used to detect seismo-ionospheric precursors (SIPs) of the 14 November 2019 M7.1 Indonesia Earthquake. The GIM TEC and F7/C2 NmF2 (the F2-peak electron density) significantly increase specifically over the epicenter on 25-26 October, which indicates SIPs of the 14 November 2019 M7.1 Indonesia Earthquake being detected. Upward motions of the F7/C2 RO electron density profiles suggest that the eastward electric fields have been enhanced during the SIP days of the 2019 M7.1 Indonesia earthquake. The F7/C2 IVM ion velocities show that the seismo-generated electric fields associated with the SIPs of the 2019 M7.1 Indonesia earthquake are 0.34-0.64 mV/m in the eastward direction. The results demonstrate that F7/C2 can be employed to detect SIPs in the ionospheric plasma, which might shed some light on earthquake prediction or forecast.