利用由全球電離層圖 (Global Ionosphere Map, GIM) 全電子含量 (total electron content, TEC) 和國際參考電離層 (International Reference Ionosphere, IRI) 研究1999至2019年 (含第23至24個太陽週期) 期間之電離層半球不對稱現象，其中令10.7 cm太陽輻射通量 (F10.7) 為太陽活動指標。研究結果顯示GIM TEC不對稱現象具有明顯之地方時間、季節、太陽活動、地磁緯度、地理緯度效應。夜間電離層半球不對稱較白天的明顯；冬夏至之電離層半球不對稱較春秋分的顯著；低太陽活動之半球不對稱較高太陽活動為明顯；地磁緯度27.5°及72.5°附近之電離層半球不對稱則至為顯著。整體而言，電離層半球不對稱與F10.7呈負相關，而半球不對稱的擾動卻與F10.7的呈正相關。進一步，利用IRI之TEC、電離層F2層峰電子濃度NmF2、層峰高度hmF2來驗證電離層半球不對稱現象，比對其與GIM TEC半球不對稱之差異。研究結果呈現GIM TEC之電離層半球不對稱效應與IRI的十分吻合。

The ionospheric hemisphere asymmetry phenomenon has been studied by using the Global Ionosphere Maps (GIM) Total Electron Content (TEC) and the International Reference Ionosphere (IRI) model during the period from 1999 to 2019 (including solar cycles 23 to 24). The 10.7 cm solar radio flux (F10.7) is used to denote the solar activity. Results display that the GIM TEC hemisphere asymmetry yields significant local time, seasonal, solar activity, geomagnetic latitude, and geographic longitude effects. The asymmetry is more pronounced in nighttime than daytime, and more remarkable during the winter/summer solstices than the spring/autumn equinoxes. The hemisphere asymmetry is inversely proportional to F10.7 prominent, and however, fluctuations of the hemisphere asymmetry yield a positive correlation with F10.7. The hemisphere asymmetry becomes very prominent at 30° and 75°, geomagnetic latitudes. Moreover, TEC, F2-peak electron density of NmF2, and F2-peak height of hmF2 derived from IRI are also used to examine the hemisphere asymmetry. In general, the hemisphere asymmetry of the GIM TEC well agrees with that of IRI.

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