青藏高原夏季大气热源低频振荡特征及其传播途径
投稿时间:2019-08-15  修订日期:2019-10-18  点此下载全文
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贾巧 气象灾害省部共建教育部重点实验室/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 1733871945@qq.com 
基金项目:国家自然科学基金项目(面上项目)
中文摘要:本文基于1979-2017年NCEP/NCAR逐日再分析资料计算了大气热源Q1,研究了青藏高原夏季Q1低频振荡特征及传播途径。结果表明:高原夏季Q1低频振荡以准双周振荡(QBWO)为主,并且Q1 QBWO第一模态扰动中心位于高原中南部,第二模态表现为高原东南-西北偶极型,这两个模态代表着Q1 QBWO传播过程中的不同位相。而高原QBWO主要来源于两条途径:第一条,源自中国东部沿海的QBWO信号向西移动影响高原;第二条,QBWO信号来自于高原南部。以上两个信号经4、8位相在高原汇合增强。汇合后,整体开始向西北移动,当移出高原时,减弱消失。同时低频环流场表现为中纬度异常气旋和反气旋相间的波列形式,并自东向西移动,靠近(远离)高原时,低频环流系统增强(减弱)。这是影响高原夏季大气热源QBWO产生和维持的重要原因。
中文关键词:青藏高原  大气热源  准双周振荡  传播途径
 
Low-Frequency Oscillation of Summer Atmospheric Heat Source over the Tibetan Plateau and its Propagation Pathways
Abstract:The Low-Frequency Oscillation (LFO) of the atmospheric heat source (Q1) and its propagation pathways over the Tibetan Plateau (TP) during boreal summer are investigated. The results show that: (1) The LFO of Q1 over the TP is dominated by Quasi-Biweekly Oscillation (QBWO). The first mode of Q1QBWO is characterized by a perturbation center over the central and southern TP (STP). The second mode is characterized by a southeast-northwest dipole structure over the TP. These two leading modes represent different phases of the Q1QBWO over the TP. (2) The Q1QBWO over the TP mainly comes from two pathways: the first one, the signal originating from the eastern coast of China propagates westward to the TP ; the second , The Q1QBWO signal is originated from the STP. The above two signals are merged and enhanced by the 4th and 8th phases over the TP and move westward/northwestward. When it moves out of the TP,the merged signal gradually weakened and disappeared. (3) The low-frequency circulation presents as anomalous cyclones and ant-cyclones that alternate in the mid-latitude and move from east to west. When approaching (away from) the TP, circulation systems are enhanced (weakened). This is an important factor for the occurrence and maintenance of Q1QBWO over the TP.
keywords:Tibetan Plateau  atmospheric heat source  Quasi-Biweekly Oscillation  Propagation Pathway
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