Effect of the westward-propagating zonal wind anomaly on the initial development of quasi-biweekly oscillation over the South China Sea during early summer  

作　　者：CHEN Guang-Hua WANG Xu CHEN Guang-Hua WANG Xu(Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China)

机构地区：Center for Monsoon System Research,Institute of Atmospheric Physics,Chinese Academy of Science

出　　处：《Atmospheric and Oceanic Science Letters》2017年第1期89-95,共7页大气和海洋科学快报（英文版）

基　　金：supported financially by the National Basic Research Program of China[grant number 2014CB953902];the National Natural Science Foundation of China[grant numbers 41275001 and 41475074]

摘　　要：The characteristics of quasi-biweekly oscillation（QBWO） over the South China Sea during early summer are investigated.Composite results demonstrate that QBWO convection and the meridional wind anomaly exhibit local variation,while the zonal wind anomaly displays zonal propagation.Besides,emergence of the zonal wind anomaly precedes the enhancement of QBWO convection,suggesting the zonally propagating zonal wind anomaly may play a key role in initiating the development of QBWO convection.Diagnostics of the convergence of moisture flux and divergence tendency indicate that QBWO convection is primarily modulated by eddy divergence.Among the contributing factors in the divergence tendency,the β effect associated with the zonally-propagating zonal wind anomaly makes an appropriate phase difference with the eddy divergence,which can contribute to the convergence tendency in the initial stage of QBWO.As a result,QBWO convection and the meridional wind anomaly are enhanced,thus facilitating the initial development of QBWO convection over the SCS during early summer.以往许多研究揭示了夏季西太平洋及其南海地区准双周振荡纬向西传的传播特征。然而,本研究通过对南海初夏(5-6月)准双周振荡典型事件的合成分析发现,南海初夏准双周对流和经向风异常表现为局地变化的特征,而纬向风异常却表现为纬向西传特征。通过对准双周散度异常倾向的诊断分析,表明与纬向风异常相关的效应异常项领先于准双周散度异常,可以加强准双周对流及经向风异常的强度,从而促进南海夏初准双周振荡的初始发展。

关 键 词：Westward-propagating zonal wind quasi-biweekly oscillation South China Sea early summer 

分 类 号：P732[天文地球—海洋科学]