2016東亞極端寒潮事件研究;A Study of the 2016 Extreme Cold Surge Event in East Asia

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題名:	2016東亞極端寒潮事件研究;A Study of the 2016 Extreme Cold Surge Event in East Asia
作者:	簡毓瑭;Chien, Yu-Tang
貢獻者:	大氣科學學系
關鍵詞:	東亞寒潮;極端事件;cold surge;extreme event
日期:	2017-07-24
上傳時間:	2017-10-27 12:26:15 (UTC+8)
出版者:	國立中央大學
摘要:	前人研究點出盤踞在東亞-西太平洋高層的反氣旋系統阻擋了高空南向的冷平流，冷空氣被限制在此高壓系統之下流動，形成東亞地區獨有的寒潮現象。寒潮為東亞季風區主要的天氣現象，然而2016一月發生極端寒潮事件使得東亞大幅降溫並在副熱帶地區發生固態降水，造成嚴重的經濟損失。此罕見現象一般被認為由負北極震盪影響，然而往年負北極震盪並無造成如此嚴重的寒害。因此引起了我們的好奇心，以此研究探討是否有其他因素導致此劇烈寒潮事件。　　透過分析各層流場和其氣候背景場，極端寒潮發生前在西伯利亞一帶和東南亞地區有明顯的反氣旋環流距平。從高層綜觀環境場分析，北太平洋反氣旋環流的西進阻擋原在大陸東岸的氣旋式環流向東移動，並間接造成西伯利亞上空的高壓脊不斷累積質量並發展為反氣旋環流。另外配合東南亞反氣旋環流距平，在1/23寒潮爆發前之較大的氣壓梯度力，提供了利於冷空氣快速南下的環境。一旦當中高緯度氣旋環流前的阻擋減弱消失後，後方西伯利亞冷空氣一次釋放，將東亞大氣急凍。　　由不同的分析方法切入皆能反應北太平洋反氣旋環流的影響：由阻塞指標及流函數渦流場垂直剖面顯示出此環流有向西演進的趨勢，並且凸顯出東亞高層的氣旋系統和西伯利亞高層反氣旋被阻擋的過程。此外，利用傅立葉分析保留大氣4-15個波的短波顯示極鋒短波列和西風帶短波列在22日寒潮發生前之空間分布上的相位一致，加深高層槽線，並有利於冷空氣南下，同時短波在北緯60度的時序圖也證明了反氣旋環流西進的特徵。　　斜溫圖和再分析資料則說明了寒潮發生前整層大氣水氣充足，經水氣傳輸分析發現印度半島高層加深的槽線使額外的水氣傳輸至華南一帶，而底層水氣受前寒潮高壓出海的尾流影響，將熱帶水氣傳送至台灣鄰近地區。;Previous studies demonstrate that the tropical anticyclone on the upper troposphere blocks the southward cold-air advection so that the cold air can only flow underneath this high system, in turn, this unique phenomenon named cold surges, naturally occurs over East Asia. During January 2016, an extreme cold surge event with a dramatic cooling in East Asia occurred and introduced a surprising solid-form precipitation around the subtropical areas and leading to serious economic losses. Following the synoptic development, a prominent anticyclonic anomaly over the Siberian region was observed prior to the extreme event. It turns out that there was a westward moving anticyclone over the western Pacific, which acts as a blocking agent to prevent the regular eastward migrating cyclones activity over North Asia resulting in the accumulation of air mass over Siberia that develop into a ridge. The daily vertical cross-section of the streamfunction clearly shows that the anticyclone over the western Pacific evolves with a westward movement and yet provide the blocking function toward the newly developing ridge over the west Siberia. Further analysis based upon the short wave regime (wave number 4-15), it appears that the polar short wave and westerly short wave coupled with each other when they merged over East Asia, the upper-level trough was deepened. On the other hand, the air columns over East Asia exhibit a sufficient water vapor content prior to the extreme event. The water vapor flux analysis also demonstrates how the additional water vapors were transported from the deepened trough over the Indian peninsula to that over East Asia.
顯示於類別:	[大氣物理研究所 ] 博碩士論文

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