本文自1987年5∼6月「臺灣地區中尺度實驗」(Taiwan Area Mesoscale Experiment; TAMEX) 期間，選取弱綜觀強迫之環境下具有明顯海陸風局部環流之個案，利用地面氣象觀測與高空風觀測資料，以運動學法求取臺灣西南部四個小局部區域內各高度之散度與垂直速度，配合降水觀測以討論垂直速度的日夜變化與臺灣西南部地區海陸風環流之發展及其和對流降水的相關。結果顯示垂直運動有顯著的日夜變化，上升運動主要發生在白天，並於午後達到最大值；下降運動主要出現在深夜至清晨，但強度較上升運動為弱。在海風發展較早和較強的日子，較早出現較強的上升運動；而在陸風發展較晚和較弱的日子，則較晚出現較弱的下降運動。此段期間臺灣西南部降水量之日夜變化亦與垂直運動之日夜變化一致，西南部白天之降水量較夜間為多，且亦在午後達到最大，顯著的降水均發生在午後有地形坡度的內陸上升運動區內。比較臺灣西南部四個小局部區域內的垂直速度分佈，有地形坡度的內陸區域垂直速度隨時間變化較平地區域為大，此可能乃因山區受太陽輻射增溫和冷卻的效應比平地區域顯著，同時該區東高西低的地形，白天亦有助於上坡風的發展和海風深入內陸後的舉升，因此加強了局部輻合與上升運動。

　　　　　Characteristics of vertical motions over southwestern Taiwan in weakly synoptic forcing condition during May-June 1987 Taiwan Area Mesoscale Experiment (TAMEX) were studied using surface and upper-air observations. Vertical motion was computed over four local-scale areas using kinematic method. Under the weakly synoptic forcing days, the sea breeze typically prevailed in the daytime and land breeze occurred at night. Diurnal variation of the vertical velocity was mainly controlled by the land-sea breezes and the associated slope winds with upward motion occurring in the sea-breeze period and downward motion in the land-breeze period. Upward motion occurred in the daytime and reached a maximum in the afternoon. Downward motion occurred in the nighttime and was weaker than upward motion. Diurnal variation of rainfall was apparently modulated by these local circulations. Generally, rainfall maximum was observed during the period of the strongest upward motion. Upward motion due to sea breeze covergence and upslope wind provided an essential triggering for the initiation of afternoon convection.