南海大气季节内振荡特征及其与ENSO循环的关系
投稿时间:2012-05-02  修订日期:2013-09-06  点此下载全文
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祝丽娟 卫星海洋环境动力学国家重点实验室/国家海洋局 第二海洋研究所, 浙江 杭州 310012  
王亚非 中国气象科学研究院 灾害天气国家重点实验室, 北京 100081 yfwang@cams.cma.gov.cn 
高桥正明 东京大学 气候系统研究中心, 日本 东京 T153  
基金项目:国家海洋局青年海洋科学基金(2013256);国家自然科学基金资助项目(41375091);国家重点基础研究发展计划(973计划)项目(2012CB417202);灾害天气国家重点实验室基本科研业务费
中文摘要:采用1979—2009年NCEP/NCAR再分析资料、NOAA向外长波辐射(outgoing long-wave radiation,简称OLR)及扩展重建海表面温度资料,对南海大气季节内振荡(Intra-seasonal Oscillation,简称ISO)特征及其与ENSO循环的关系进行了诊断分析。结果表明:1)南海大气ISO的30~60 d周期在5—10月均显著。一般年南海大气ISO的对流传播在纬向上存在东传和西传,在经向上具有南北半球季节性摆动的特征。以低频动能表征的南海大气ISO强度年代际变化特征明显,近31 a来趋势增强,年变化呈单峰结构,峰值在7—8月。2)南海大气ISO的对流与ENSO循环显著相关,其强度在El Ni?o(La Ni?a)年减弱(增强)。与一般年对比,南海大气ISO对流在El Ni?o和La Ni?a年均表现为西传减弱、北传显著。北传特征表现为强对流活跃带于春季(4—5月)北跳至北半球(在La Ni?a年最北可至35°N),但在北半球的传播方向与一般年相比存在显著差异。3)南海大气ISO强度与ENSO循环关系密切,在El Ni?o(La Ni?a)年减弱(增强),两者表现为约半年(6~8个月)的滞后相关。Ni?o3区海表面温度异常序列与南海大气ISO强度的相关在中西太平洋地区和El Ni?o成熟前的春、秋季最显著,同时相关中心伴随低频动能高值区东移。
中文关键词:气候学  南海  30~60d季节内振荡  ENSO循环  低频动能
 
Characteristics of ISO over the South China Sea and its relationship with ENSO cycle
Abstract:The characteristics of the 30—60 d intra-seasonal oscillation(ISO) over the South China Sea(SCS) and its relationship with ENSO cycle are diagnosed by using the NCEP/NCAR reanalysis data,NOAA outgoing long wave radiation(OLR) data and extended reconstructed sea surface temperature from 1979 to 2009.The results are as follows:(1)The 30—60 d period of the ISO over the SCS is significant from May to October.The ISO over the SCS during normal years,which is represented by the convection in company with the ISO,presents eastward and westward longitudinal propagation and seasonal latitudinal sway between the two hemispheres.The ISO intensity over the SCS represented by the low frequency kinetic energy(KE) shows interdecadal variation with an increasing trend during the past 31 years as well as monthly change with a peak from July to August.(2)The ENSO cycle has a significant influence on the ISO convection over the SCS,and the convection intensity tends to be suppressed(intensified) during El Ni?o(La Ni?a) years.In contrast with normal years,the westward propagation of the ISO convection over the SCS weakens while the northward spread is notable during both El Ni?o and La Ni?a years.The northward spread is characterized by the northward leap of active convection band from the Southern Hemisphere to the Northern Hemisphere in the spring(from April to May),and the band can reach 35°N during La Ni?a years.However,the spread direction in the Northern Hemisphere is distinctly different from that in the normal years around September.(3)The ISO intensity over the SCS has a close relationship with ENSO cycle.The ISO intensity would weaken(strengthen) during El Ni?o(La Ni?a) years and has about half a year(6—8 months) lag correlation with the occurrence of mature El Ni?o(La Ni?a) event.The correlation between ISO intensity and the sea surface temperature anomaly over the Ni?o3 region is the most striking over the western and central Pacific in the spring and autumn before the mature El Ni?o occurs.The correlation centers also spread eastward accompany with the high value centers of low frequency KE.
keywords:climatology  South China Sea  30—60 day intra-seasonal oscillation  ENSO cycle  low frequency kinetic energy
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