中高纬大气ISO对夏季鄂海阻高形成和维持的调节作用
投稿时间:2019-10-01  修订日期:2019-12-11  点此下载全文
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杨双艳 南京信息工程大学 气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
李天明 南京信息工程大学 气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044
夏威夷大学马诺阿分校 大气科学学院 国际太平洋研究中心, 檀香山 夏威夷 96822 
timli@hawaii.edu 
基金项目:国家重点研发计划(2018YFC1505803);江苏省高校自然科学基金资助项目(18KJB170015);南京信息工程大学人才引进启动基金(2018R027)
中文摘要:运用1979-2015年的逐日NCEP-DOE再分析资料,探讨了夏季鄂霍次克海阻塞高压(简称"鄂海阻高")与中高纬大气季节内振荡(简称"ISO")之间的可能联系。研究发现,ISO扰动与夏季鄂海阻高在关键区(130°~160°E,60°~75°N)有最好的耦合关系,且关键区位势高度表现出显著的10~30 d的振荡周期。超前滞后合成分析表明,与鄂海阻高相联系的ISO扰动具有明显的向西传播的特征。波活动通量分析结果显示,波能量在中高纬140°W附近累积,因此西传的ISO扰动可能源自中高纬140°W附近。对位势倾向方程的诊断结果显示,动力作用对关键区位势高度的时间变化起主要作用。进一步运用尺度分析表明,在夏季鄂海阻高发生和维持的过程中,ISO经向风引导的平均涡度平流对位势高度的时间变化起主导作用。
中文关键词:鄂海阻高  中高纬季节内振荡  波活动通量  位势倾向诊断
 
The role of intraseasonal oscillation at mid-high latitudes in regulating the formation and maintenance of Okhotsk blocking in boreal summer
Abstract:In this study,by using daily data from the Department of Energy Reanalysis at the National Center for Environmental Prediction,dating from 1979 to 2015,we investigated the connection between Okhotsk blockings and mid-high latitude atmospheric intraseasonal oscillation(ISO) in the boreal winter.The results showed that the ISO perturbation over a key area of 60°-75°N,130°-160°E is the most greatly co-variated with Okhotsk blockings.The averaged geopotential height over this key area exhibits a statistically significant 10 to 30-day periodicity.By applying lead-lag composite analysis,it is revealed that the ISO perturbation associated with the Okhotsk blocking activity exhibits pronounced westward propagation.The perturbation initiates at about 140°W,triggered by intraseasonal wave energy accumulation.A geopotential tendency diagnosis reveals that the time change rate of the geopotential height over the key area is primarily attributed to the dynamic process.In addition,the results of a scale analysis show that the advection of mean vorticity by the ISO meridional flow plays a dominant role in the time change rate of the geopotential height during the occurrence and maintenance of the summertime Okhotsk blockings.
keywords:Okhotsk blocking  intraseasonal oscillation at mid-high latitude  wave activity flux  diagnosis of geopotential endency
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