利用福爾摩沙衛星三號(FORMOSAT-3/COSMIC)全球定位系統掩星觀測實驗(GPS Occultation eXperiment, GOX)用來觀測電離層電子濃度垂直分佈。本論文相互比較2007年磁赤道地區Jicamarca地面電離層探測儀和同地點福衛三號資料。首先，制定一套篩選流程挑選探測儀上空具有物理意義的福衛三號資料，例如:F2層層峰高度HmF2須在200公里高以上。分析比較此兩觀測資料的電離層HmF2和峰值濃度NmF2之日、季、年差異。獲知福衛三號大多低估兩參數，而兩者差異亦會受到背景電子濃度季節變化的影響。NmF2比較顯示福衛三號在白天可能受赤道電子濃度異常區（equatorial ionization anomaly）的影響而產生高估之現象，尤其於當地時間下午14:00LT前後時段至為明顯。 The FORMOSAT-3/COSMIC (F3/C) program applies the radio occultation technique to derive the electron density profiles, using the GPS occultation experiment (GOX) onboard the F3/C. In this study, we examine the ionospheric data concurrently observed by the F3/C and Digisonde Portable Sounder (DPS) at Jicamarca (12°S, 283°W, 1°N geomagnetic) in 2007. First, we use the criteria to choose the F3/C data that have the physics meanings (For example: the F3/C F2-peak height, HmF2, must be higher than 200KM). Then, we compare the F2-peak density (NmF2) and HmF2 of F3/C with those of Jicamarca DPS in different time periods. Results show that the F3/C generally underestimates the values of NmF2 and HmF2. The underestimates are mainly affected by the seasonal variation in the horizontal electron density. On the other hand, the F3/C overestimates the NmF2 in the afternoon period, especially at about 14:00LT. The greater electron density at the equatorial ionization anomaly accounts for the overestimate.
