夏季(5-10月)南海准双周和20～60天振荡的年代际变化特征  

THE DECADAL VARIATION OF QUASI-BIWEEKLY AND 20～60-DAY INTRASEASONAL OSCILLATION IN SOUTH CHINA SEA IN SUMMER(MAY—OCTOBER)

作　　者：李春晖[1] 何超[1] 郑彬[1] 谷德军[1] 林爱兰[1] 

机构地区：[1]中国气象局广州热带海洋气象研究所/广东省区域数值天气预报重点实验室,广东广州510640

出　　处：《热带气象学报》2016年第5期577-587,共11页Journal of Tropical Meteorology

基　　金：973项目(2014CB953901);国家自然科学基金项目(41205069;41375095;41675096;41575043;41505067);广东省科技计划重点项目(2012A030200006);广东省气象局气象科技项目(2013B08)共同资助

摘　　要：通过周期和波谱分析，指出南海对流夏季（5—10月）具有显著的准双周振荡（10-20天，QBWO）和20～60天振荡（ISO）周期。在南北向传播上，南海对流QBWO和ISO均以波数为2的向北传播为主。在东西方向传播上，QBWO以波数为1的向西传播为主，而ISO则以波数为1的向西和向东传播为主。在大气环流发生突变的三个不同年代下（1958-1976年、1977-1993年和1994—2011年），QBWO强度、传播次数、频次和传播波谱能量均呈现逐渐增强的趋势。ISO强度的变化为正常略弱、较弱和较强，传播次数、频次和传播波谱能量则为较强、较弱和较强。导致这些变化的可能因子也有所不同，海气相互作用和水汽对流条件对QBWO的变化起了共同主导作用。对ISO而言，纬向风垂直切变影响更为重要。Using period and wave number-frequency analysis, the sub-seasonal variability of summer （May-- October） convection over the South China Sea exhibits two dominant timescales, one with a quasi-biweekly （QBWO） period （10 - 20 days ） and the other with an intraseasonal oscillation. The northward propagation spectrum is much stronger than the southward, meridional propagating QBWO and ISO with wave number 2. In the zonal propagation, for the QBWO mode, the westward propagation spectrum with wave number 1 is the strongest. But for the ISO, the spectrums of the westward propagation and eastward propagation with wave num- ber 1 are quite the same. During three different time of the atmospheric circulation of the decadal change, namely 1958--1976,1977--1993 and 1994--2011, the QBWO intensity, propagation numbers, frequency and spectrum energy tend to enhance gradually. Different from the QBWO mode, the intensity of ISO experiences periods of being normal and slightly weaker, weaker and stronger variation, while the propagation numbers, frequency and spectrum energy are the stronger, weaker and stronger. The factors that cause these changes are different. The air-sea interaction and the water vapor convection conditions played a leading role together in the change of QBWO. For the ISO mode, vertical zonal wind shear is more important.

关 键 词：南海 准双周 20~60天振荡 年代际 

分 类 号：P426.613[天文地球—大气科学及气象学]