福爾摩沙衛星五號（福衛五號，FORMOSAT-5）於台灣時間2017 年8 月25 日發射，運行於高度約720 公里與軌道傾角98.28 度的太陽同步軌道（繞極軌道）上，經過赤道的當地時間約為10:30 與22:30，以每兩日的飛行週期便可涵蓋全球。福衛五號搭載的科學酬載為先進電離層探測儀（Advanced Ionospheric Probe, AIP），其由中央大學研發團隊設計開發完成，以量測電離層的電漿特性。AIP 自2017/11 以來於夜側對電離層進行實地量測，其所觀測到的離子密度可建構電離層的全球離子密度分布。歷經兩年半（2017/11～2020/4）的全球離子密度分布顯示，可明確地看到赤道地區電漿密度結構（Four-peak or Three-peak Plasma Density Structure）與中緯度電漿密度帶（Mid-latitude Plasma Density Band or Enhancement）隨經度與季節而變化，佐證AIP 可準確地長期探測電離層並提供良好品質的離子密度資料。;A FORMOSAT-5 satellite has been launched on 25 August 2017 CST into a 98.28° inclination sun-synchronous orbit at 720 km altitude along the 10:30/22:30 local time sectors. The orbital coverage provides a great opportunity to survey terrestrial ionosphere from equatorial to polar region every two days. Advanced Ionospheric Probe (AIP) is a piggyback science payload developed by National Central University for the FORMOSAT-5 satellite to in-situ measure ionospheric plasma characteristics. The global ion density distributions observed by FORMOSAT-5/AIP in the pre-midnight sector are available since November 2017. Through the seasonal global ion density distributions from November 2017 to April 2020, longitudinal and seasonal variations of four-peak (or three-peak) plasma density structure near equator and mid-latitude plasma density bands (or enhancements) are clearly observed. It is indicated that FORMOSAT-5/AIP can provide high quality data to identify long-term ionospheric ion density variations
