台灣北部地區局部環流之研究

Northern Taiwan Local Circulation Study

蔡清彥(Ching-Yen Tsay)

《大氣科學》 15卷2期 (1987/10) Pp. 179-198

摘要

臺灣北部地區因受地理環境影響，兼受海陸風和山谷風所左右。經分析風場實測質料，發現夏季日間之氣旋式輻合氣流場，相當顯著，其滙聚中心，位置雖非固定，但約略均居於大屯山與七星山附近。夏季夜間局部環流型式，與日間相反，屬反氣旋輻散場，其中心亦大致在大屯山及七星山附近。冬季同地區受東北季風影響，未有顯著之氣旋式輻合場，或反氣旋式輻散場，僅因地形阻擋，令吹入之季風分為三支，分別沿基隆河及淡水河谷進入台北盆地，滙合後經鶯歌附近流出。梅雨期在日間大範圍不論盛行風風向如何，大屯山區均可能產生輻合場。夜間則當大範圍風力較弱時，大屯山區方有可能形成輻散場。至於秋季，則在日間大範圍盛行之風，其風力較弱峙，則在大屯山區可形成輻合場。秋季夜間，亦唯風力較弱時，大屯山區可產生輻散場。但當夜間盛行東南風或西南風，台北盆地亦可能誘發輻合場。分析臺灣北部地區夏冬兩季，各等高面之氣流場發現，在夏季低層環流兼受海陸風系統及大範圍繞山（陽明山區）氣流的影響。在冬季，陽明山區兩側低層環流則主要受大範圍繞山氣流所控制。本文亦從事臺灣北部地區局部環流簡易數值模式之建立工作。考慮三種陸地加熟的情形，來模擬地形導引，海陸風及山谷風三種作用。

關鍵字

局部環流 ； 季節變化 ； 地形導引 ； 海陸風 ； 山谷風 ； 數值模擬

並列摘要

The local circulations in northern Taiwan are studied by using the surface wind and PIBAL observations. In summer, Local circulations are cont rolled by land-sea breeze, mountain-valley winds and the channeling effect. In the daytime, there is a strong cyclonic and convergent flow pattern with its circulation center over Tatunshan and Chihsingshan mountain area. On the contrary, a weak anticyclonic and divergent flow pattern is found over the same area in the night time. On the other hand, the local circulations in winter are mainly controlled by the northeast monsoon and the channeling effect. The northeast monsoon flows into Taipei Basin through Keelung and Tanshui Valleys. The confluence of these flows is located near Yinko. In the daytime of Mei-Yu period, there is a cyclonic and convergent flow pattern with its circulation center located over the area of Tatunshan. On the contrary an anticyclonic and divergent flow pattern is found in night-time over the same area. In autumn, a cyclonic and convergent flow pattern in the daytime and an anticyclonic and divergent flow pattern in the night time is found only when the prevailing wind is weak. When southeast or southwest wind prevails in the night-time, a cyclonic and convergent flow pattern with its circulation center in Taipei Basin is also found.A simple numerical model is also established in this paper. It is able to simulate channeling effect, land-sea breeze and mountain-valley winds.

並列關鍵字

local circulation ； seasonal variation ； channel effect ； land-sea breeze ； mountain-valley wind ； numericalsimulation