Global Occurrence Rates of Ionospheric Plasma Density Irregularities Observed by Advanced Ionospheric Probe Onboard FORMOSAT-5 Satellite During Solar Minimum

　　A remote sensing satellite, FORMOSAT-5, developed by National Space Organization (NSPO) carried a piggyback science payload, Advanced Ionospheric Payload (AIP), for space weather and seismo-ionospheric precursor study.  To meet the science requirements, AIP could be operated in different measurement modes to obtain various plasma parameters.  The first AIP measurement was performed on 7 September 2017 to obtain the first-orbit data and started routine operation in November the same year.  Global ion density and ion velocity/temperature distributions were available every two days and four days, respectively.  AIP was regularly operated in a sampling rate 1,024 Hz to maximize useful science data.  In this poster, global occurrence rates of pre-midnight low-latitude ionospheric plasma density irregularities will be shown from AIP science data collected since winter 2017.  The results indicate that seasonal variations of the occurrence rates during the solar minimum (2017/11-2019/12) are distributed very similar to but have lower magnitudes than those observations by ROCSAT-1/Ionospheric Plasma and Electrodynamics Instrument dataset (1999-2004) during solar maximum.