朱等(2007)已說明2003年7月3日夜間，在五分山氣象雷達觀測到的回波並不是真的天氣系統。同時，綜觀天氣分析也顯示在臺灣地區是屬於穩定的南氣環境而且沒有降水。本研究利用WRF數值模式重建個案當時之大氣環境且著重在導管的時間與空間演變。此外，藉由資料的後處理與視覺化繪圖技術，吾人可以清楚呈現大氣導管的位置。 WRF之數直模擬結果顯示(1)夜間來自西側且伴隨西南氣流的暖濕空氣與來自東側的南來氣流在雷達站附近聚集，導致低層垂直水氣梯度的增加。在此情形下，修正折射指數之垂直梯度增加而形成陷捕層。(2)少異常回波出現在五分山東南方時，21m高且強度3 M-unit的陷捕層正好位於雷達站所在之處。(3)當電達回波停留在五分山的西北方時，近海岸地區的空中導管高度化變介於230~623m之間、厚度變化為185~350m。強度則介於4.7~11.2M-unit之間。(4)由於雷達站東側水氣到達的時間較西側早，故雷達站東南方異常回波較早發生。(5)臺灣西側向北輸送的水氣平行於臺灣海峽，致使該異常回波可維持數小時之久。

Chu et al.(2007) have demonstrated that the echoes observed by weather radar at Wufensan are not the real weather system during the night on July 3rd, 2003. Meanwhile, the synoptic weather analysis also shows a stable environment around Taiwan area with no precipitation. In this study, the WRF (Weather Research and Forecasting) model is used to reproduce the atmospheric environment of that day and focus on the temporal and spatial evolution of ducted layer. Besides, with the assistance of post-processing and visualization techniques, one can clearly identify the location of the atmospheric ducts. The simulation results are shown below: (1) during the night, the warm and moist air associated with the southwesterly flow from the west and the southerly flow from the east are cumulated near Wufensan and increase the vertical moist gradient in the low layer. Under this situation, the vertical gradient of the modified refractivity index increase and the trapping layer occurs. (2) As the abnormal radar echo appeared to the southeast of Wufensan, there just exists a trapping layer with 21 m height and 3 M-unit intensity at the radar station. (3) During the radar echo stay still in the northwest of Wufensan, the height of the elevated ducts near coastal area changes between 230 and 623 m and the thickness varies from 185 to 350 m. Also, its modified refractivity index changes between 4.7~11.2 M-unit. (4) Since the arriving moist air from the east of Wufensan is earlier than that from the west, the abnormal echoes at the southeast of radar station occur first. (5) In the west of Taiwan, the water vapor transported northward is parallel to the Taiwan Strait and maintains the radar echo for several hours.