結合GPS掩星與低軌道繞極衛星之異質平台觀測於大氣溫溼度反演

全球定位系統GPS之掩星觀測與低軌道地球繞極衛星之輻射強度觀測，兩者均可用來反演三維大氣之溫度與溼度分佈，近年來更嘗試將此兩者之異質平台觀測合併使用，其反演成效不僅優於各單一系統之反演結果，更可以降低反演大氣垂直溫溼度時之不確定性。但目前合併使用時，除了是採取統計回歸反演法之外，二種觀測之配對（co-location），亦直接採取投影至地表之經緯度之垂直配對方式。本研究提出一嶄新的空間幾何配對方式，係考慮掩星觀測於大氣層中，會隨高度而改變的正切點位置，同時低軌道衛星之觀測，對於某一掃瞄角（scan angle）於不同高度之地面投影點及非柱狀之視場空間涵蓋範圍，予以斜向配對，更嘗試以物理反演演算法，將二者資料融合對大氣垂直溫溼度反演。實驗結果顯示，二者融合後的演算法除了仍保有優於單一反演系統之成效外，證實了高品質掩星觀測可以協助降低經輻射強度觀測而反演的產品誤差，新開發的配對方式，更能提高反演準確度，提高反演產品於後續應用時的可使用度。

關鍵字

福衛三號；掩星觀測；高光譜紅外線垂直探測儀AIRS ；三維大氣溫溼度反演

並列摘要

Observations from different platforms may be used together to retrieve atmospheric temperature and moisture vertical soundings, which may provide better accuracy profiles than either system alone from past studies. However, those combined retrieval algorithm followed a vertical-based co-location and statistical procedure, which lacks accurate 3D observational geometry and physical radiative transfer model iterations. In this study, we propose a co-location method that searches for radio occultation (RO) refractivity whose tangent points fall within the field-of-view of the radiances observation, and suggest this method improves the retrieval accuracy over co-location without considering observation geometry, in term of co-location using only observation latitude and longitude. The preliminary results confirm the importance of the newly developed slant path co-location technique. The experiments also yield that the synergistic use of both RO and direct radiances observations has the better retrieval performance than either observation individually through a physical based retrieval algorithm.

並列關鍵字

FORMOSAT-3/COSMIC ； radio occultation ； AIRS ； atmospheric sounding retrieval

國際替代計量

結合GPS掩星與低軌道繞極衛星之異質平台觀測於大氣溫溼度反演

全文下載

主題瀏覽