干旱气象

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1979—2008年夏季青藏高原东南部降水的低频振荡统计特征

刘炜1,2,周顺武2,王美蓉2,单幸2刘新1   

  1. 1.内蒙古自治区气候中心,内蒙古呼和浩特010051;2.南京信息工程大学大气科学学院,江苏南京210044
  • 出版日期:2016-08-31 发布日期:2016-08-31
  • 通讯作者: 周顺武(1968-),男,教授,主要从事高原气象研究. E-mail:zhou@nuist.edu.cn
  • 作者简介:刘炜(1986-),女,内蒙古人,助理工程师,主要从事短期气候预测. E-mail:liuwei.05@163.com
  • 基金资助:

    国家重点基础研究发展规划项目(2012CB955204)、国家自然科学基金项目(41275095)共同资助

tatistic Characteristics of  Summer Precipitation Low-frequency Oscillation over the
 Southeast of the Tibetan Plateau from 1979 to 2008

LIU Wei1,2, ZHOU Shunwu2, WANG Meirong2, SHAN Xing2, LIU Xin1   

  1. 1. Inner Mongolia Climate Center, Hohhot 010051, China;
    2. College of Atmospheric Science, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • Online:2016-08-31 Published:2016-08-31

摘要:

利用青藏高原1979—2008年地面逐日降水资料及NCEP/NCAR逐日再分析资料,对高原东南部夏季降水的低频振荡特征进行统计分析,并讨论了该地区典型旱、涝年夏季降水的低频振荡特征以及低频环流的传播特征。结果表明:(1)青藏高原东南部作为高原夏季降水大值区,其低频振荡主要表现为10~20 d准双周振荡(QBWO)和30~60 d季节内振荡(ISO),其中QBWO最显著;(2)该地区旱、涝年夏季降水的低频振荡存在差异。其中,旱年夏季降水以QBWO为主,而涝年夏季降水的ISO和QBWO均很重要,且QBWO的方差贡献在旱年更显著,而ISO的方差贡献在涝年相对更重要;(3)青藏高原高空100 hPa散度的ISO和QBWO普遍以驻波为主,其次是从高原向东部传播,但也存在少数由东部向西传播进入高原的低频振荡,表明夏季青藏高原主要是低频振荡的源地,有时也受外来影响。

关键词: 降水, 低频振荡, 传播特征, 高原东南部

Abstract:

Based on the daily precipitation from 83 weather stations in the Tibetan Plateau and NCEP/NCAR reanalysis daily data with 2.5°×2.5° spatial resolution, the low-frequencyoscillation characteristics of summer precipitation over the southeast of the Tibetan Plateau from1979 to 2008 were statistically analyzed. Furthermore, the characteristics of summer precipitationlow-frequency oscillation and propagation of low-frequency circulation in typical flood and drought years were emphatically discussed. The results are as follows: (1) The precipitation in the Tibetan Plateau gradually decreased from southeast to northwest during 1979-2008, and it wasmaximum in the southeast of the Tibetan Plateau. There were two main periods of low-frequencyoscillation of summer precipitation in the southeast of the Tibetan Plateau with 10-20 d Quasi-biweekly Oscillation (QBWO) and 30-60 d Intra-seasonal Oscillation (ISO), and the QBWO of summerprecipitation was most significant. (2) The low-frequency oscillation of summer precipitation in flood and drought years over the southeast of Tibetan Plateau was significantly different. The QBWO of summer precipitation was main type in drought years, while ISO and QBWO were both significant in flood years. Furthermore, the variance contribution of QBWO of summer precipitation was more significant in drought years, while that of ISO was relatively more significant in flood years over the southeast of the Tibetan Plateau. (3) The standing wave was the main transmission mode of ISO and QBWO of divergence on 100 hPa over the southeast of the Tibetan Plateau, secondly it was the propagation from the southeastern Plateau to the eastern mainland. However, there were also a few oscillation waves propagating from the eastern mainland to the southeastern Plateau. In summary, the southeastern Plateau was main source of low-frequency oscillation in summer, but sometimes it was also affected by the external.

Key words: precipitation, low-frequency oscillation, propagation characteristics, southeastern Tibetan Plateau

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