地球赤道上空的平流層中，緯向風場大約每兩年會規律性的發生東風和西風交互變換的現象，此即為大氣的「準雙年震盪」（Quasi-biennial oscillation，QBO）。自1953年開始觀測以來到2015年初，準雙年震盪都非常規續的持續發生。但在2015年末至2016年初的交界季節，原本應該向下移動的西風帶突然反轉向上移動，和有規律而來的東風相遇。這種異常現象持續了近半年，直到2016年7月才恢復為以往正常的東西風交替形態。對於異常QBO的研究自2016年底開始成為極重要的研究課題。學者們認爲來自中緯度的行星尺度西向羅士比波與強烈聖嬰現象是造成異常QBO的可能原因。截至目前（2017年底）為止，幾乎所有的研究皆着重在異常QBO的成因，以及如何修正預報模式。主要的研究對象都放在西向羅士比波身上，對於另一個主導並提供能量產生QBO現象的赤道大氣克耳文波（Kelvin wave），尚未有人加以討論。本計畫將利用衛星及大氣模式的資料，研究克耳文波在此異常時期之傳播特性以及在異常東西風交替時能量供輸方面的細節。除此之外，本計畫亦將探討能傳播至電離層的超快速克耳文波在此QBO異常時期之傳播特性以及是否對電離層造成額外的擾動。 ;The Quasi-Biennial Oscillation is a regular variation of the zonal winds that blow high at the stratosphere above the equator. Strong eastward and westward winds in the region completely change direction alternatively. The full cycle takes roughly 28 months, making it the most regular slow variation in the atmosphere from 1953 when QBO has been constantly documented. Unexpectedly, the evolution of the QBO during the Northern hemisphere winter of 2015-2016 shows different features. A band of easterly winds began to form above the westerlies, as expected, at the end of 2015, but it was cut off by a new band of westerly winds that appeared below it, keeping the QBO from completing a normal cycle. Propagation of planetary scale Rossby waves from the NH mid-latitudes into the tropical region and the strong 2015-2016 ENSO effects may be the clues to the causes of this QBO anomaly. In this research, we are going to study the propagation characteristics of the atmospheric Kelvin wave during this QBO anomaly since the QBO is forced by the interaction of Kelvin waves and mixed Rossby-gravity waves with the zonal mean flow. Moreover, propagation features of the ultra-fast Kelvin wave that travels to Ionosphere will also be investigated to examine with more ionospheric disturbances.
