An observing system simulation experiment for FORMOSAT-5/AIP detecting seismo-ionospheric precursors

  • Author(s): Jann-Yenq Liu and Chi-Kuang Chao
  • DOI:


  • Keywords: Earthquake, Seismo-ionospheric precursor, ROCSAT-1/IEPI, FORMOSAT-5/AIP, Ion density, Ion velocity, TEC
  • Spatial analyses are essential to confirm the seismo-ionospheric precursors being observed
  • Seismo-ionospheric precursors of the ion velocity are for the first time found
  • The seismo-generated electric fields are for the first time estimated

AIP (advanced ionospheric probe) on board FORMOSAT-5 is a next version and advanced generation science payload of IPEI (ionospheric Plasma and Electrodynamics Instrument) on board ROCSAT-1 (i.e. FORMOSAT-1).  To see whether FORMOSAT-5/AIP can be used to detect seismo-ionospheric precursors (SIPs) or not, we examine the ion density, ion temperature, and the ion velocity probed by ROCSAT-1/IPEI, as well as the global ionospheric map (GIM) of the total electron content (TEC) derived by ground-based GPS receivers during the 31 March 2002 M6.8 Earthquake in Taiwan.  It is found around the epicenter area 1-5 days before the earthquake that the GIM TEC significantly decreases, while the ROCSAT-1/IPEI ion density significantly decreases and ion velocity in the downward direction anomalously increases.  The anomalous decreases in the ROCSAT/IEPI ion density and the GIM TEC concurrently appear around the epicenter area 1-5 days before the earthquake, which suggests that FORMOSAT-5/AIP can be employed to detect SIPs.  Moreover, the increase in the downward velocity implies that a westward electric field generated during the earthquake period being essential.

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