【作者】 常蕊； 张庆云； 李荣凤；

【Author】 Rui Chang1,2,Qing-yun Zhang1 and Rong-feng Li1 1.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing,100029,China 2.Public weather service center of China Meteorological Administration,Beijing 100081,China

【机构】 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； 中国气象局公共气象服务中心；

【摘要】 根据1958-2001年SODA海洋同化资料和NCAR/NCEP再分析资料,利用等密度面P-矢量计算法,作者分析探讨了北太平洋副热带西部模态水(简称STMW)季节演变和年际变化与前期东亚-北太平洋中高纬大气环流异常的关系。分析指出:(1)STMW的体积具有显著的季节变化特征:春季体积最大、强度最强,夏秋逐渐减弱,冬季体积最小、强度最弱。研究进一步指出,STMW体积的季节变化与西北太平洋中纬地区的海表风应力及净热通量的季节演变过程紧密联系在一起,它在一定程度上反映了西北太平洋中纬度大气环流季节性演变的特征。(2)年际尺度上,夏季STMW指数具有显著的3年左右的振荡周期,其年际变化不仅与海洋自身动力过程有关,还与前冬亚-太中高纬大气环流异常引起STMW形成区风应力动力混合及海表净热通量等因子异常有关:冬季东亚季风环流偏强(弱),STMW形成区洋面风应力的动力混合作用及海表热力蒸发加强(减弱),使得海洋对流混合加强(减弱),进而加强(抑制)了混合均匀的低位涡水体进入温跃层,随着季节演变,造成夏季STMW强度加强(减弱)。夏季STMW强弱年际变化是前期亚-太中高纬大气-海洋相互作用过程的综合反映,前冬东亚环流强弱变化与夏季STMW强度变化的联系可能是通过东亚环流的强弱变化影响STMW形成区的动力混合及海表热通量过程实现。更多还原

【Abstract】 Based on the SODA₁.4.2 and NCAR/NCEP monthly reanalysis data from 1958 to 2001,the new understanding of the relationship between the seasonal-annual variations of the Northwestern Subtropical Mode Water（STMW） and the mid-high latitude atmospheric circulation over East Asia-Pacific is studied using the P-vector method.It is showed that:（1） The STMW is of significant seasonal variation:its volume increases in spring,then gradually weaken in summer and autumn,and eventually shrank to the smallest in winter.It is also investigated that the significant seasonal variation of STMW is closely linked to the seasonal evolution of sea surface wind stress and net heat flux over the Northwestern Pacific,leading to a perfect reflection of the seasonal evolution of mid-high latitude atmospheric circulation anomalies over East Asia to some extent.（2） Meanwhile,on the inter-annual timescale,the 3-year-period is one of the most significant oscillation cycles of the summer STMW index.Besides the ocean dynamic process,the annual variation of STMW is also controlled by the wind stress curl and net heat flux anomalies,which is relevant to the abnormal configuration of the mid-high latitude atmospheric circulation anomalies over East Asia during the precious winter.When the previous winter monsoon is strong（weak） over East Asia,the wind stress entrainment and sea surface net flux over the formation area of STMW are enhanced（reduced）,leading to the strong（weak） oceanic mixing process.Eventually,more（less） water mass with low potential vorticity come into the thermo-cline area through subduction,causing the strong（weak） summer STMW event as time goes.Therefore,the intensity of summer STMW reflects the integrated features of mid-high latitude atmospheric and oceanic circulation over the East Asia-Pacific during the previous winter,which maybe can impose an effect on the East Asia climate anomaly.更多还原