廣布全球的測站以及良好的資料品質，使得全球定位系統(GPS)成為測量電離層全天電子含量的新寵，而低地球軌道衛星(LEO)如CHAMP，SAC-C，以及福爾摩沙衛星三號等以無線電掩星觀測提供水平方向射線，是為最新探測電子濃度鉛直分布之利器。本文模擬結合GPS及LEO觀測技術，並改良一般常用於電離層斷層掃描之MART演算法，建立二維及三維高解析度電離層暫態斷層掃描的新方法，以探察大範圍電離層結構變化。模擬結果顯示此一新方法能有效降低MART演算法對於初始猜值好壞之依賴，因此可在有限資訊之下得到更好的結果，而加入LEO水平方向射線或地面電離層探測儀之觀測確實有助於提升反演結果之正確性。

The global positioning system (GPS) has been employed to calculate the total electron content (TEC) with advantages of its worldwide coverage and high time resolution. Recent developments on low earth orbit (LEO) satellites with the radio occultation (RO) technology, such as CHAMP , SAC-C, or FORMOSAT-3 COSMIC, provide the horizontal (tangent ray) observations to derive the vertical profiles. In this study, the two observations are combined to reach a new approach, the Multiplicative Algebra Reconstruction Technique (MART) is modified to reconstruct and obtain a high spacial resolution three-dimensional ionospheric electron density structure. The simulations indicate that the new approach significantly reduces the dependence of MART on initial values and achieves better reconstructions. Results show that observations from LEO satellites and/or priori information from co-located ionosondes can greatly improve the performance of inversion distributions.

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