臺灣北部與鄰近地區春夏中尺度線狀對流系統特徵與環境條件之相關分析

Correlation Analysis for the Environmental Conditions and Characteristics of Mesoscale Line-Type Convective Systems in Spring and Summer Over Northern Taiwan and Its Vicinities

陳泰然(George Tai-Jen Chen) ； 王尹懋(Mark Ying-Mao Wang)

《大氣科學》 26卷2期 (1998/06) Pp. 149-156

摘要

本文選取1988~1993年2~7月間發生於台灣北部與鄰近地區的50個線狀對流系統，分析雷達回波顯示之系統特徵與環境條件參數間以及系統特徵參數間之相關性，並探討具有顯著水準相關性之物理意義與詮釋。研究結果顯示，線狀對流系統之移速主要由垂直於線狀對流主軸的中高對流層平均氣流之平流過程主宰。這些系統在海上時，雷達回波長度愈長者其生命期愈長且移速愈慢；但登陸後，此種相關性已不復存在。此種相關性在後造型與不同生命階段之線狀對流亦極顯著。研究結果亦顯示，鋒面位置在決定線狀對流系統特徵占有重要角色。此外，研究發現潛在不穩度與對流可用位能不僅為鋒前型與破線型線狀對流發展之必要條件，且其大小亦決定它們生命期之長短。

關鍵字

線狀對流 ； 環境條件 ； 生命階段

並列摘要

Fifty cases of line-type convective systems over northern Taiwan and its vicinities in spring and summer of 1988∼1993 were selected in this study. Correlations between the characteristics of line convection as revealed by radar echoes and the environmental conditions were analyzed. Physical interpretatioin and explanation were given for those correlations with statistical significance.Results showed that the movement of line convection was mainly controlled by the advection process of mean flow normal to the major convective line in the mid-and upper-troposphere. When the line-type convective system was over the ocean, the life time was longer and the movement was slower for the system with a longer length scale. When the system moved over land, this relationship no longer existed. This relationship was also clearly shown for the back-building type and at the different evolution stages of line-type convection. Results also showed that the frontal position played a crucial role in determining the characteristics of the line-type convection. Additionally, it was found that the potential instability and CAPE not only were the necessary conditions for the development of line convection, but also were positively correlated to the duration of line-type convection.

並列關鍵字

Line-type convection ； Environmental condition ； Life stage