「福爾摩沙衛星三號」(FOMOSAT-3/COSMIC)於2006年4月成功發射升空，其利用無線電波掩星(Radio Occultation; RO)折射觀測原理，得到「偏折角」(bending angle)及「折射率」(refractivity)資料，進而推求得知大氣層溫度、氣壓、乃至水汽等垂直剖面。目前6顆低軌道(LEO)衛星每日產生近2000個分布全球的GPS RO掩星觀測。由於其近乎全球均勻分佈，大量涵蓋傳統觀測不易取得的海上區域資訊，而且垂直解析度很高(200 m ~ 1 km)，故能彌補傳統探空及一般衛星觀測之不足。「福衛三號」的科學目標之一，即希望GPS RO觀測資料能被大量應用在中央氣象局數值天氣模式作業，以期能有效提高模式之預報準確度。 國際間重要的數值預報作業中心均證實，GPS RO觀測資料透過數值資料同化過程，可以改善數值模式的溫度及高度場等大氣初始場結構，進而提高數值天氣預報的準確度。中央氣象局數值天氣預報系統也自2009年7月，正式將福衛3號衛星的觀測資料納入作業性的資料同化系統中運用。基於歐美國家對相關資料同化的技術仍持續不斷的改進與發展，我們希望藉由本計畫的推動，能與國內外數值資料同化領域的專家共同合作，參考國外的技術趨勢，進一步改善中央氣象局應用福衛3號掩星觀測資料之能力，並且探討RO資料在數值天氣預報的效益。 The FORMOSAT-3/COSMIC (FS3) satellites were successfully launched on April 2006. With the radio occultation (RO) technique, the FS3 satellites can provide the bending angle and refractivity data, which can be used to infer the temperature, pressure, and humidity profiles. Currently the FS3 satellites include 6 LEO satellites, which provide approximately 2000 GPS RO soundings per day globally. With the vertical resolution of 1 km or finer and the nearly homogeneous distribution around the globe, the GPS RO measurements are considered as a highly helpful dataset which will complement the existing data sources used by the numerical weather prediction (NWP) system of the Central Weather Bureau (CWB). Several major weather prediction centers (like the ECMWF in the Europe or the NCEP in the United States) demonstrate that the GPS RO observation can improve the temperature, pressure, and humidity fields, using the data assimilation technique, which can further improve the NWP accuracy. The CWB NWP system has officially included the GPS RO data from the FS3 satellites into daily operation since July 2009. Because the technology in the data assimilation community is in continuous advancement, we would like to cooperate with international outstanding experts through this research project. By following the development trends in major NWP centers in the United States or Europe, we hope improve the data assimilation capability and enhance the potential benefits of the GPS RO data for the NWP. 研究期間：10001 ~ 10012
