气候变化领域集成服务门户(CCPortal): Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption

CCPortal

DOI	10.5194/acp-21-9839-2021
	Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption
	Kang M.-J.; Chun H.-Y.
发表日期	2021
ISSN	1680-7316
起始页码	9839
结束页码	9857
卷号	21 期号:12
英文摘要	In January 2020, unexpected easterly winds developed in the downward-propagating westerly quasi-biennial oscillation (QBO) phase. This event corresponds to the second QBO disruption in history, and it occurred 4 years after the first disruption of 2015/16. According to several previous studies, strong midlatitude Rossby waves propagating from the Southern Hemisphere (SH) during the SH winter likely initiated the disruption; nevertheless, the wave forcing that finally led to the disruption has not been investigated. In this study, we examine the role of equatorial waves and small-scale convective gravity waves (CGWs) in the 2019/20 QBO disruption using Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) global reanalysis data. In June-September 2019, unusually strong Rossby wave forcing originating from the SH decelerated the westerly QBO at 0-5g N at g1/450hPa. In October-November 2019, vertically (horizontally) propagating Rossby waves and mixed Rossby-gravity (MRG) waves began to increase (decrease). From December 2019, the contribution of the MRG wave forcing to the zonal wind deceleration was the largest, followed by the Rossby wave forcing originating from the Northern Hemisphere and the equatorial troposphere. In January 2020, CGWs provided 11% of the total negative wave forcing at g1/443hPa. Inertia-gravity (IG) waves exhibited a moderate contribution to the negative forcing throughout. Although the zonal mean precipitation was not significantly larger than the climatology, convectively coupled equatorial wave activities were increased during the 2019/20 disruption. As in the 2015/16 QBO disruption, the increased barotropic instability at the QBO edges generated more MRG waves at 70-90hPa, and westerly anomalies in the upper troposphere allowed more westward IG waves and CGWs to propagate to the stratosphere. Combining the 2015/16 and 2019/20 disruption cases, Rossby waves and MRG waves can be considered the key factors inducing QBO disruption. © 2021 Min-Jee Kang.
语种	英语
scopus关键词	climatology; equatorial wave; gravity wave; quasi-biennial oscillation; Rossby wave; Southern Hemisphere; stratosphere; wave force; wave propagation
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/246767
作者单位	Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
推荐引用方式 GB/T 7714	Kang M.-J.,Chun H.-Y.. Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption[J],2021,21(12).
APA	Kang M.-J.,&Chun H.-Y..(2021).Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(12).
MLA	Kang M.-J.,et al."Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.12(2021).