摘要
基于海洋与大气再分析数据,对1950—2010年间的El Ni?o事件进行了分类与合成分析;对比分析了两类El Ni?o事件的发展过程。结果发现,两类El Ni?o事件暖信号的发展经历了不同的过程:中部型El Ni?o暖信号的起源主要受到北太平洋低层大气环流的影响,而东部型El Ni?o暖信号来源于热带太平洋海洋温跃层。在中部型El Ni?o前期冬、春季,北太平洋涛动型大气环流使副热带北太平洋信风减弱,SST增暖。在"风-蒸发-SST"机制的作用下,SST正异常传播到热带太平洋中部,热带太平洋中西部产生西风异常,大气对流发展,热带太平洋东部受东风异常的控制。当中部型El Ni?o发展成熟时,大气对流中心与海温异常中心位于热带太平洋中部;在东部型El Ni?o前期冬、春季,西北副热带太平洋的西风异常使热带太平洋产生暖开尔文波,并向东传播到热带太平洋东部,使其表层海温增暖。在Bjerkness正反馈机制的作用下,表层暖信号发展并向西传播。东部型El Ni?o发展成熟时,大气对流中心与海温异常中心位于热带太平洋东部。
This study used reanalysis dataset to classify El Ni5o events during 1950--2010 and eomposited two types of E1 Nino to study the difference in mechanism of them. It is found that the warm signal of cen- tral Pacific E1 Nino originates form interaction between north Pacific lower atmosphere general circulation and SST, while the warm signal of eastern Pacific E1 Nino originates form tropical Pacific thermocline. During spring of the central Pacific E1 Nino year, the North Pacific Oscillation is active, which relaxing the trade wind, generating positive SST in the subtropical north Pacific. The positive SST anomaly spread to the central tropical Pacific at the mechanism of "wind-Evaporation-SST", and forces westerly wind anoma- ly along the Central and Western Tropical Pacific, Eastern Pacific is control by eastern wind anomaly, which contributes to the occurrence of Central Pacific E1 Nino. The Eastern Pacific E1 Nino is transformed form central Pacific La Nina-like SST mode. Westerly wind anomaly controls the West Tropical Pacific before the emergence of SST anomaly, which warms thermocline. The warming signal in the thermocline propagates to Eastern Tropical Pacific, warming the upper Ocean. SST anomaly in Eastern Tropical Pacif- ic is enhanced and spreads westward at the mechanism of ocean-atmosphere interaction, contributing to the occurrence of Eastern Pacific EI Nino.
出处
《中国海洋大学学报(自然科学版)》
CAS
CSCD
北大核心
2017年第9期11-20,共10页
Periodical of Ocean University of China
基金
国家自然科学基金项目(41276002
41130859)
国家重大研究计划发展项目(2012CB955603
2013CB956201)
国家自然科学基金-山东海洋科学研究中心联合基金项目(U1406401)资助~~