2004/05冬季台灣寒潮之探討：阻塞高壓的影響

The Cases Study of the Cold Surge in Taiwan during 2004/05 Boreal Winter: The Influence of Atmospheric Blocking

洪志誠(Chi-Cherng Hong) ； 賈新興(Hsin-Hsing Chia)

《大氣科學》 35卷2期 (2007/06) Pp. 151-165

摘要

2004/05年冬季，北半球阻塞高壓出現頻繁，期間台灣共發生四次寒潮（氣候平均1~2 次）。本文以NCEP重分析日平均資料探討2004/05年冬季台灣四次寒潮與北半球阻塞高壓的關係。
研究發現，四次寒潮皆發生在阻塞持續或消散期間，寒潮爆發時東亞噴流增強，且沿著副熱帶噴流出現正壓波列。此波列在穿越東亞時振幅出現局部放大，伴隨之低層北風分量可以加速寒潮南移。阻塞高壓則透過以下過程影響寒潮：(1)加強西伯利亞冷高壓，(2)加強東亞噴流，透過正壓不穩定機制增加華南一帶的低層北風分量。

關鍵字

阻塞高壓 ； 寒潮 ； 東亞噴流 ； 波列

並列摘要

Cold surges of East Asia and the blockings over Eurasia were unusually active during winter 2004/05. The relationships between clod surges and boreal blockings were investigated by analyzing NCEP/NCAR reanalysis data in this study.
Our study showed all the cold surges were identified during the persisting or decaying stage of boreal blocking, when the Siberian surface high and East Asia Jet were detected with enhancement amplitude. It was noted that the cold surges were preceded by upstream upper-level wave trains, which the coupled lower-level northerly over South China to help the quick southward penetration of cold air mass. The diagnosis of kinetic energy conversion of perturbation revealed that the upper wave trains drew energy from time mean flow at the entrance of East Asia Jet. The blockings have an effect to enhance the East Asia Jet and thus amplify the lower-level northerly over South China. In addition, the upper ridge accompanied with the blocking may strength the Siberian surface high, which is correlated with the cold surges.

並列關鍵字

Cold surge ； Blocking ； East Asia Jet ； Wave trains