| MJO与北半球高纬地区冬季地表气温异常的联系 |
| |
| 引用本文： | 崔静,杨双艳,LI Tim.MJO与北半球高纬地区冬季地表气温异常的联系[J].气象,2021(1):49-59. |
| |
| 作者姓名： | 崔静 杨双艳 LI Tim |
| |
| 作者单位： | 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;夏威夷大学国际太平洋研究中心 |
| |
| 基金项目： | 国家重点研发计划(2018YFC1505803、2018YFC1505602);江苏省高校自然科学基金项目(18KJB170015);国家自然科学基金项目(41975048);南京信息工程大学人才引进启动基金(2018R027)共同资助。 |
| |
| 摘 要： | 基于1979—2016年NCEP-NCAR逐日再分析资料研究了热带季节内振荡(MJO)和北半球冬季高纬地区地表气温(SAT)之间的联系。利用实时多变量MJO(RMM)指数,将MJO分为8个位相,其中位相2(位相6)对应于位于印度洋地区的正(负)对流。不同MJO位相下的SAT合成结果显示MJO第二位相后的5~15 d,北半球高纬地区(60°~90°N、180°~60°W)有明显的负SAT异常;由于热带异常加热信号的改变,在MJO第六位相后的5~15 d该地区则对应于显著的正SAT异常。该地区温度的垂直结构在各个位相下也表现出类似的分布特征。合成的500 hPa位势高度异常场显示,在温度负(正)异常的位相对应有明显的位势高度负(正)异常,这种环流异常主要是由与热带对流异常相联系的向东北方向传播的罗斯贝波列所引起的。通过对波活动通量的计算,推断该东北方向传播的罗斯贝波列很可能是罗斯贝波能量频散的结果。合成的700 hPa比湿异常场和SAT之间在存在着较好的对应关系,考虑到对流层中层的比湿与向下长波辐射之间存在着正相关关系,说明该温度异常也可能与辐射过程相关。上述分析表明与MJO对流相关的大尺度环流异常对高纬地区季节内SAT变率有重要影响,该异常SAT信号可能来自平流输送和辐射过程等。准确把握MJO位相与SAT异常信号的联系也可以为北半球高纬地区SAT的延伸期预报提供一些可靠线索。
|
| 关 键 词： | MJO 地表气温 罗斯贝波列 波活动通量 |
Relationship Between the Madden-Julian Oscillation and High-Latitude Surface Air Temperature During Boreal Winter |
| |
| Institution: | (Key Laboratory of Meteorological Disaster,Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disaster,Nanjing University of Information Science and Technology,Nanjing 210044;International Pacific Research Center and Department of Atmospheric Sciences,University of Hawaii at Manoa,Honolulu,Hawaii USA) |
| |
| Abstract: | The relationship between the Madden-Julian oscillation(MJO)and the high-latitude wintertime surface air temperature(SAT)is examined based on NCEP-NCAR reanalysis daily data during 1979-2016.The real-time multivariate MJO(RMM)index,which divides the MJO into eight phases,where Phase 2(Phase 6)corresponds to the enhanced(reduced)convection over the Indian Ocean and Maritime Continent,is used.A significant positive SAT anomaly over northern high-latitude region of(60°-90°N,180°-60°W)is found 5-15 days following MJO Phase 2,while a negative SAT anomaly appears over the same region about 5-15 days after the MJO is detected in Phase 6,as the tropical forcing changes sign.An analysis of the lagging composite of the geopotential height at 500 hPa indicates that the Arctic SAT anomaly is a result of a north-eastward propagating Rossby wave train associated with the tropical convection anomaly of the MJO,which may have great impacts on intraseasonal SAT variability over high latitude.An analysis of the wave activity flux indicates that the north-eastward propagating Rossby wave train is likely a result of Rossby energy propagation.Composite maps of the specific humidity at 700 hPa also show close relationship with the SAT signals in high latitudes,due to the positive relationship between mid-troposphere specific humidity and downward longwave radiation.These analyses suggest that large-scale circulation anomalies associated with the MJO convection may have great impacts on high-latitude SAT signals,which can result from both advective and radiative processes.Hence,the MJO phases provide useful information for the extended-range forecast of high-latitude surface air temperature during boreal winter. |
| |
| Keywords: | MJO surface air temperature Rossby wave train wave activity flux |
| 本文献已被 CNKI 维普 等数据库收录！ |
|
