本研究採用一新發展的方法，嘗試解決一個自1987年即存在於熱動力反演演算法中的問題，也就是用都卜勒雷達合成風場所反演出來的熱動力場(即: 溫度及氣壓的擾動場)，在垂直結構上的不確定性。這個不確定性來自於傳統方法上的限制: 也就是反演的熱動力場在每個水平面上與真實值都相差一個未知常數，這個未知常數以擾動場的水平平均的形式存在。本研究所用的新方法，其優勢在於首創藉由結合狀態方程和垂直方向動量方程式，可由一個單點的地面站觀測開始垂直積分，獲得該未知常數的垂直分布，而非如前人研究所採用的，必須仰賴時間解析度極低的探空氣球資料。 本研究使用Observing System Simulation Experiment(OSSE)的架構，測試此方法的可行性，並進一步應用於2008年西南氣流實驗#IOP 8的真實個案。首先使用都卜勒雷達觀測的徑向風進行風場合成，並利用此三維風場資訊反演熱動力場，再使用新方法校正熱動力場垂直結構。結果顯示，以新方法得之水平平均相似於探空觀測得之，並且成功校正其垂直結構，證實了此方法在分析劇烈天氣的情形下有一定的可信度。 ;This study adopts a newly developed method in solving the vertical structure uncertainty of retrieved thermodynamic fields (e.g., pressure and temperature perturbations) from multiple-Doppler radars synthesized winds, which hadn’t been solved yet since 1987. This uncertainty comes from the limitation of the traditional method: an unknown constant exists at each layer. This unknown constant exists with a form of horizontal average. The advantages of this new method is that the vertical uncertainty can be solved by a single in-situ observation only by combining the Equation of State and vertical integration instead of relying a sounding observation with much lower temporal resolution.
We conduct OSSE framework at first and the data collected during SoWMEX (Southwestern Monsoon Experiment) IOP #8 , which is a heavy rainfall event occurred on June 14 2008, are further investigated the performance of the new scheme. In this study, using the data from Doppler radar, WISSDOM(WInd Synthesis System using DOppler radar Measurements) helps to provide the wind information and a thermodynamic retrieval is conducted by TPTRS(Terrain Permitting Thermodynamic Retrieval Scheme). The horizontal average of each layer can be obtained either by the sounding or the station. The results show that the horizontal averages of thermodynamic fields obtained from the stations are quite similar to which obtained from the soundings. The vertical structure has been correctly solved. Overall, it demonstrates a high reliability using the new scheme.
