Why so many double and triple La Niña events emerged recently

 

Prof. Bin Wang

University of Hawaii, USA

 

邀请人/报告会主持人 ：吴国雄 院士

 

2023年8月17日（星期四）15:00

3号楼第三会议室 

 

报告摘要: 

Five out of six La Niña events have lasted two to three years since 1998. Over the past century ten multiyear La Niña (ML) events had an accelerated trend, with half occurring in the past 25 years. These ML events induce catastrophic floods over Australia, Indonesia, tropical South America, and southern Africa and droughts over the southern U. S., equatorial Africa, India, and southeast China. Why so many double and triple La Niña events emerged recently and whether they will become common remains unknown. We show that ML distinguishes from single-year La Niña by a prominent onset rate, which provides a precursor for predicting its accumulative intensity. The eight ML events after 1970 primarily follow either a super El Niño (SE) or a central Pacific El Niño (CPE), forming two types of ML: SE2ML and CPE2ML. The leading coupling process for ML’s onset and persistence is thermocline feedback in SE2ML and zonal advective and upwelling feedback in CPE2ML. We hypothesize that the historical increase of ML is rooted in the western Pacific (WP) warming. WP warming enhances zonal advective feedback, promoting more frequent SE and CPE events and increasing the odds for ML. It also strengthens thermocline feedback, accelerating CPE2ML’s onset, leading to a sizable heat discharge and a longer recovery. The results from the large-ensemble experiments of the CESM2 model principally support the observed ML-WP warming linkages. More extreme multiyear La Niña will exacerbate adverse socioeconomic impacts if the western Pacific continues to warm relative to the central Pacific. 

 

报告人简介:

王斌（Wang Bin）博士是美国夏威夷大学（University of Hawaii）大气科学系教授，国际太平洋研究中心(IPRC)季风研究首席科学家，美国气象学会会士(AMS Fellow)，美国地球物理学会会士(AGU Fellow)，曾于2015年获得美国气象学会最高的罗斯贝研究奖（Carl-Gustaf Rossby Research Medal）表彰他的 “creative insights leading to important advances in the understanding of tropical and monsoonal processes and their predictability”。王斌教授的研究领域为气候动力学、动力气象学、热带气象学、和地球物理流体力学。在季风气候、气候变化、热带季节内震荡、海气相互作用以及气候可预报性等方面发表了许多开创性成果。曾任夏威夷大学气象系主任、世界气候研究计划（WCRP）/气候变率与可预报性（CLIVAR）/亚澳季风研究委员会主席、亚太经合组织气候中心（APCC）科学顾问委员会主席、中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室（LASG）学术委员会海外主任 。