本論文分析1996太陽黑子極小年中壢中央大學校園內（24.91°N, 121.24°E geographic）數位電離層探測儀（Digisonde Portable Sounder； 簡稱DPS）所觀測記錄三萬多張之電離圖以研究位於台灣地區赤道異常區之上空電離層中之散塊E層（Sporadic E layer, Es層）變化，除電腦自動判圖外，並輔以人工判圖以增加資料之可信度。統計最大反射頻率foEs，反射虛高h’Es以及Es層出現機率之整年變化情形。結果顯示台灣地區foEs以3~4MHz為主，而於夏季有明顯較高的趨勢。h’Es主要分布在100至105km之間，冬季h’Es之變化幅度較夏季為明顯。一天24小時Es層出現機率與h’Es於不同的月份而有單峰及雙峰的現象。Es層變化與太陽的活動性並無明顯相關，但於強烈的磁擾動時其出現機率有減少之趨勢。仿照異調散射雷達ISR電子密度隨高度及時間變化圖之表現方式處理DPS 之觀測資料以探討Es層變化與中界層現象之相關性。 The sporadic E (Es) layer is an irregular layer occurred in the ionosphere. Unlike the normal E layer critical frequency (foE), the foEs and h’Es are highly variable in time and space. To understand the occurrences of the Es layer in the equatorial anomaly region, more than 30,000 ionograms recorded by a digisonde portable sounder, DPS, at National Central University, NCU, (24.91∘N, 121.24∘E) during 1996 (solar minimum) have been examined. The intermediate and descending layers in the valley between E and F regions can also be observed by NCU DPS. In this study, variations of the Es layer at various local times, seasons, solar radiations, geomagnetic conditions and the observation of intermediate and descending layers are presented and discussed.
