台灣地區閃電與降雨的分類及其氣候特徵

譚振威(Chan-Vai Tam)

指導教授 ： 王國英

國立中央大學/地球科學學院/大氣物理研究所/碩士(2006年)

摘要

本研究分析及探討台灣地區1989-2005年間，三種不同天氣系統的閃電和降雨氣候特徵。三種天氣系統分別為颱風型天氣對流系統、局部地區熱力產生近似滯留的深對流型天氣系統（局部熱對流型天氣系統）和其他對流型天氣系統。接著利用個案分析來探討在三種不同的天氣型態之下，閃電跟地面降雨在時間和空間上的相關性。
結果顯示台灣地區閃電發生最密集的區域是在中央山脈西側，發生比較頻繁的月份為5月至9 月。在局部熱對流型天氣系統期間發生的閃電是三種天氣系統之中最多的，並且集中在西部南北向輸電線路的兩側，其-CG跟+CG發生次數的比值（-CG閃電數除以+CG閃電數）約為19，也是最大的。2003-2005年IC跟CG的比例約為20。
在降雨特徵方面，颱風型降雨量佔年總降雨量的比例在1989-2005年間呈現上升的趨勢，從~20%上升至~40%。6月至8月期間在西南部的降雨佔平均年雨量的30%。這三個月的降雨主要是由颱風和局部熱對流型系統產生的。颱風型降雨的時序跟總降雨時序的相關係數為0.79；局部熱對流型系統的是0.13；其他對流型的則是0.72。
個案分析顯示，在局部熱對流型天氣系統個案中，IC閃電與對流型降雨發生的地點與範圍十分一致，CG則是發生在雨量極大值附近。在其他對流型天氣系統的個案中，IC閃電十分稀少，CG只會在局部性強降雨的地方發生。

關鍵字

雲對地閃電 ； 雲內/雲間閃電 ； 閃電氣候特徵 ； 降雨氣候特徵

並列摘要

This study discusses the climatological characteristics of lightning and surface rainfall in Taiwan under three different types of weather systems between year 1989-2005. The three different types are typhoon, local thermal convective system and other convective systems. In order to discuss the temporal and spatial correlation between lightning and surface rainfall, three cases from each type of weather system were analyzed.
Lightnings mainly occur at the west part of Taiwan, on the west side of the Central Mountain Range. Lightning occurances are more often during May to September. The greatest part of lightnings happen during the local thermal convective systems and mainly gather up around the north-south oriented power transmission line at the west part of Taiwan. The ratio between –CG and +CG (the number of -CG divided by the number of +CG) during local thermal convective system is about 19, which is the largest among the three types of weather systems. The ratio between IC and total CG during year 2003-2005 is about 20.
The percentage of typhoon rainfall within annual total rainfall exhibits a rising trend between year 1989-2005, from ~20% to ~40%. During June to August, each month contributes about 30% of the annual total rainfall at the south-west part of Taiwan. The rainfall occur during these three months are mainly caused by typhoon and local thermal convective system. The correlation coefficient of typhoon rainfall and annual total rainfall is 0.79, while that of local thermal convective rainfall and other convective rainfall is 0.13 and 0.72 respectively.
In the local thermal convection system case, the area of the occurance of IC lightnings and rainfall are in good agreement, while CG lightnings happen around the maximum of the surface rainfall. In the other convective case, IC lightnings are very rare, and CG lightnings only happen in the area where local heavy rainfall occurs.

並列關鍵字

none

參考文獻

Tapia, A., J. A. Smith, and M. Dixon, 1998：Estimation of convective

謝信良、簡國基與王時鼎，2003：潭美颱風高雄豪雨事件之天氣分析。大氣科學，

洪景山，2002：雲對地閃電和雷達回波參數之相關：個案研究。大氣科學，30，

林熹閔，1999：雲對地閃電與降水關係之研究。大氣科學，27，1，75-98。

林熹閔與郭鴻基, 1996: 1994年南台灣夏季午後對流之研究。大氣科學，24，4，