印度洋—西太平洋对流涛动的季节内特征  

Intraseasonal Characteristics of the Indo–West Pacific Convection Oscillation

作　　者：张净雯[1,2,3] 李建平[1,4] 李艳杰[1] 

机构地区：[1]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,北京100029 [2]中国科学院大学,北京100049 [3]成都市气象局,成都610072 [4]北京师范大学全球变化与地球系统科学研究院,北京1000875

出　　处：《大气科学》2015年第2期221-234,共14页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金重点项目41030961;91437216;国家自然科学青年基金项目41205034

摘　　要：本文利用30~60天带通滤波资料,考察了不同季节印度洋—西太平洋区域对流活动季节内尺度变率的主要模态,发现在不同季节赤道东印度洋(5°S^10°N,70°E^100°E)和西北太平洋(5°N^20°N,110°E^160°E)对流活动均存在反相变化的关系,将之称为季节内尺度的印度洋—西太平洋对流涛动(Indo–West Pacific Convection Oscillation),简称IPCO。对IPCO两极子区域对流活动进行超前滞后相关分析,发现IPCO事件形成—发展—消亡的生命周期是由对流活动季节内振荡及其传播造成的。对流扰动首先在赤道中西印度洋形成,随后逐渐向东发展变强,在其继续变强的过程中将分两支传播:一支由赤道印度洋向北传播,至印度半岛南部后逐渐减弱消失;另一支沿赤道继续东传,在海洋大陆受到抑制,快速越过海洋大陆到达赤道西太平洋后又开始发展变强,随后北传至西北太平洋区域逐渐减弱,最终至我国长江流域中下游到日本区域消失。将这一过程划分为8个位相,详细分析了不同位相对应的环流场和降水场特征,最后给出了IPCO事件演化示意图。The principal modes of the intraseasonal variability over the Indo-West Pacific in different seasons are investigated using data filtered to retain the 30-60-tay signal. A season-independent out-of-phase oscillation of convection over the Indo-West Pacific is the most clearly defined feature, with dipole centers over the equatorial eastern Indian Ocean （EEIO） （5°S-10°N, 70°E-100°E） and western North Pacific （WNP） （5°N-20°N, 110°E-160°E） regions. This is referred to as the intraseasonal Indo-West Pacific Convection Oscillation, or IPCO. Lead-lag correlation analysis of the convective activity between EEIO and WNP shows that the life cycle （formation^levelopment-dissipation） of IPCO is driven by the behavior of the intraseasonal oscillation （ISO）. The low-frequency convection anomaly first appears over the equatorial westem central Indian Ocean. It intensifies and propagates eastward, splitting into two branches. One branch splits from the equatorial Indian Ocean northward to the south of the Indian Peninsula. The other splits eastward along the equator, which is suppressed over the maritime continent, re-amplified over the western Pacific, turns northward to the western North Pacific, and dissipates near the region lying between the middle and lower reaches of the Yangtze River and Japan. This process is divided into eight phases, and the circulation and precipitation characteristics of each phase are obtained; In conclusion, a schematic showing the IPCO event＇s life cycle is oresented.

关 键 词：30~60天振荡 低频对流 偶极型 传播 印度洋—西太平洋 

分 类 号：P427[天文地球—大气科学及气象学]