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| 題 名 | 臺灣東方近海北上颱風之合成分析與研究=A Composite and Modeling Study of the Northward Typhoons along the Coast of East Taiwan |
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| 作 者 | 林郁偉; 蕭玲鳳; 劉廣英; | 書刊名 | 華岡理科學報 |
| 卷 期 | 16 1999.05[民88.05] |
| 頁 次 | 頁29-40 |
| 分類號 | 328.55 |
| 關鍵詞 | 颱風; 副熱帶高壓; 中緯度槽線; 西藏高壓; Typhoon; Subtropical high; Tibetan high; |
| 語 文 | 中文(Chinese) |
| 中文摘要 | 本文使用國科會副熱帶資料庫中1979至1993共十五年的EC再分析資料,在臺灣百年來颱風(王等,1998)第六大類路徑,即經過臺灣東方近海北上颱風(61-64與65-69小類)中,中心在121°E到125°E,與>125°E到129°E間的,選了二十一個個案,分成東(>125°E以東)、西(125°E以西)兩類來作合成分析。分析項目包括:(1)500 hpa重力位高度場的單層合成,(2)下(850和700 hpa)、上(300和200 hpa)兩層的合成,(3)850到300 hpa之合成,以及(4)相對應之流線合成分析。 結果發現,此類颱風於移動至轉向點時,下對流層副熱帶高壓必定會東退,且隨著颱風的北上出現該副高南落的特徵。30°N以後如繼續北上則視副高中心與中緯度槽線前最大正濄度平流區與強度而定。如對照61-64與65-69兩類路徑則125°E以東合成分析此現象比較明顯。其次,由上下兩層合成圖對比可見,在此類颱風北上時,副熱帶高壓與西藏高壓呈現出上下分離的狀況。亦即「阻擋」在上對流層颱風中北方的高壓脊,實際是地面增溫所形成之西藏高壓,與副高在垂直方面並不直接銜接。此類颱風的運動路徑在長江口以南期間是由其東方的太平洋高壓脊所主導,至於後續是否向北走,則視上述高壓中心與北方西風主槽的位置與強度而定。利用η模式所得之數值模擬結果大致與分析者相同。 |
| 英文摘要 | The study is based on two data sets. First is a fifteen-year (1979-1993) reanalysis data of ECMWF which is processed by the NSC subtropical data bank. Second is the 100-year typhoon atlas of Central Weather Bureau. Twenty-one cases are selected for composite analysis form the atlas for then the centers locate in the range of 121°E and 129°E. And, depends on their influence on Taiwan, they are divided into two groups, i.e. East and West to 125°E. The composition includes (1) 500hpa, (2)lower troposphere (850 and 700hpa) and upper troposphere (300 and 200hpa), (3)850 to 300hpa geopotential height, and (4)the related streamline. The results show that subtropical high has to retreat eastward in the lower troposphere when this kind of typhoons to turn to the north. Furthermore, subtropical high will down to south when typhoon moves northward. But, further northward depends on the position of the subtropical high and maximum area of positive vorticity advection in front of the mid-latitude trough. The feature is more significant for the east group by the composite analysis. The composite figures on lower and upper troposphere are compared and show that when the typhoon moves northward the subtropical high and Tibetan high will separate, i.e., the Tibetan high and subtropical high are not connected in the vertical component. The typhoon track is mainly controlled by the Pacific high ridge during its track down south of the Yangtze estuary. Then, then continuation of northward track depends on Pacific high and the position and intensity of the trough in the westerly. The results have bben tested by 8-layer in vertical and 75 km horizontal resolution η-model through a case study. And, as show in the text, the simulation gives very good support to our composite analysis. |
本系統中英文摘要資訊取自各篇刊載內容。