本文利用1997~2006年5~6月（梅雨季）氣候資料，進行臺灣東部地區降雨與局部環流之研究。首先由北而南選取三個中尺度分析區，探討其合成風場、氣流線、溫度場及降雨量，發現臺灣東部地區的降雨與局部環流密切關連。宜蘭區在海風增強並與谷風結合時產生中尺度渦旋，此渦旋為激發午後對流與產生顯著降雨之重要機制。花蓮區西北隅高山區，環境西南氣流可結合谷風發展形成短波槽，此短波槽為調控該區降雨中心降雨強度之重要機制。此外，該區海風在增強後跨越海岸山脈入侵縱谷區，因受地形導引轉向南侵，在轉向處的迎風坡亦可形成較顯著降雨中心。上述該兩處降雨中心強度變化，均反映海風與谷風強度變化之影響。花東縱谷區南段降雨強度分布顯示由沿海向內陸遞增的規律型態，海風發展後在縱谷西側山坡迎風面則出現較大降雨中心。依地理位置與地形選取四道剖面分析結果顯示，宜蘭縣內剖面A（自沿海向內陸，沿著平地河谷區）之顯著對流降水皆受強盛的海風激發，剖面B（自沿海向內陸，位於剖面A南側的山區）的太平山站因山谷風微弱，需有大氣不穩度與水氣含量的條件配合才能產生顯著對流。花蓮縣內剖面C（自沿海向內陸沿河谷區）天祥以東顯著對流發展與否，除海風環流影響外，需有其他大氣條件配合，以西則是由較強的谷風激發。沿花東縱谷南段所選取的剖面D（自北而南），海風在傍晚時可沿縱谷南侵至鹿野，激發各處顯著對流發展。

The observational data of eastern Taiwan in May-June (i.e. Mei-Yu season) 1997-2006 provided by the Central Weather Bureau were used to study the relationship between the precipitation and the local circulations. Three mesoscale-analysis regions were selected to investigate the characteristics of the winds, streamlines, temperatures, and precipitations, and it is found that the precipitation and the local circulations were closely related. In Yi-lan region, a mesoscale vortex, which was the key mechanism for activating afternoon convection and significant precipitation, was generated when the sea breeze intensified and interacted with the valley breeze. In Hua-lien region, the environmental southwestern airflow over the high mountain area might interact with the valley breeze to form a short-wave trough, which was an important mechanism for regulating the rainfall intensity of the precipitation center in this region. Besides, after the sea breeze intensified, it could cross over the coastal mountain chain to invade the Hua-dong Valley, turning to the south due to the topographical effect, and form a significant precipitation center on the windward mountainside at the turning point. The changes in the intensity of the aforementioned precipitation centers both reflected the influence of the changes in the intensity of both the sea breeze and the valley breeze. In the southern part of the Hua-dong Valley, the distribution of the intensity of the precipitation showed a regular increasing pattern from along the coast to the inner land. The centers of larger precipitation appeared on the windward mountainside to the west of the Hua-dong Valley after the developing of the sea breeze. Furthermore, four cross sections were selected according to the geographical/topographical similarity. Temperature, intensity of precipitation, and wind field were composed by rainy days and by non-rainy days, respectively, in May-June, to investigate the climatological characteristics. The results showed that the significant convective precipitation was stimulated by the stronger sea breeze than that of non-rainy days in cross section A (from along the coast to the inner land along the river valley in the plain) in Yi-lan County. At Tai-ping-shan station in cross section B (from along the coast to the inner land in the mountainous region to the south of cross section A), the mountain breeze and valley breeze were weak, so it is obvious that though the valley breeze could stimulate the development of convection, the conditions of atmospheric instability and the amount of the moisture were still needed to bring the significant convection about. To stimulate the significant convection in cross section C (from along the coast to the inner land along the river valley) in Hua-lien County, other atmospheric conditions as well as the sea breeze circulation were needed to the east of Tian-hsiang; while to the west of Tian-hsiang, only the stronger valley breeze was needed. In cross section D (from the north to the south), which is located in the southern part of the Hua-dong Valley, stronger sea breeze could reach as far as Lu-yie along the Hua-dong Valley in the evening to give rise to the significant convection in many places on the way.