福爾摩沙三號衛星（FORMOSAT-3/COSMIC，F3/C）酬載的小型電離層光度計（Tiny Ionosphere Photometer，TIP）和美國TIMED（Thermosphere Ionosphere Mesosphere Energy and Dynamics）人造衛星酬載的全球紫外光照相儀（Global Ultraviolet Imager，GUVI）記錄全球夜間1356埃大氣暉光強度。此外F3/C另一酬載的全球定位系統掩星實驗（GPS Occultation Experiment，GOX）每天記錄約2,500筆涵蓋全球的積分電子濃度（integrated electron content，IEC）和最大層峰電子濃度（NmF2），而全球電離層圖（global ionospheric map，GIM）則每兩小時例行公佈電離層全電子含量（total electron content，TEC）。 分析比對TIP與GUVI 1356埃大氣暉光以及GIM TEC、GOX IEC與GOX NmF2同時觀測資料，並結合IRI-01與MSISE-00電離層模擬結果，可獲得適用於不同地方時間、季節和太陽活動變化的轉換因子（conversion factor），藉此同化電離層中大氣暉光和電子濃度。此一同化可用來發展一套全星載斷層掃描技術，以強化電離層斷層掃瞄地區。 此外大氣暉光觀測可用於研究夜間電離層赤道異常（equatorial ionization anomaly）結構、電漿洞（plasma cave）、大氣潮汐現象（non-migrating tide）、電漿匱乏灣（plasma depletion bay）以及威爾德海異常現象（Weddell Sea anomaly）等電離層大規模電子濃度結構與變化。論文結果顯示結合1356埃大氣暉光和電子濃度觀測是為研究夜間電離層大型結構與變化之利器，而同化資料則為未來全星載斷層掃描提供了一道新的曙光。 The tiny ionosphere photometer (TIP) of FORMOSAT3/COSMIC (F3/C) and the Global Ultraviolet Imager (GUVI) of Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) are employed to measure the nighttime OI 1356Å airglow emissions. On the other hand, the GPS occultation experiment (GOX) onboard F3/C daily derive 2,500 vertical profiles of the ionospheric electron density, while the Global Ionospheric Maps (GIM) routinely publishes the total electron content (TEC) from a GPS satellite to a ground-based receiver. A conversion factor for various local times, seasons and solar activities is obtained by cross comparing between observations of TIP/GUVI 1356Å airglow emissions, GIM TEC, GOX IEC (integrated electron content), GOX NmF2 (F2-peak electron density) and simulations of IRI-01 and MSISE-00 models. Based on the conversion factor, the assimilation between the ionospheric 1356Å airglow emission and electron density can be carried out for the development of a new space-based tomography. Meanwhile, the airglow emissions and electron density are utilized to monitor large scale structures and variations of the equatorial ionization anomaly, plasma cave, non-migrating tide, plasma depletion bay and Weddell Sea anomaly, and to understand the associated physical mechanisms. Results demonstrate that the combination observations of the OI 1356Å airglow emission and vertical electron density profiles provide a powerful tool to probe the large scale structures of the nighttime ionosphere, while the data assimilation sheds some lights on developing a TIP-GOX space-based tomography.
