doi:  10.3878/j.issn.1006-9895.1812.18167
青藏高原云团东传过程及其中MCS统计特征

The statistical characteristics of the cloud clusters’ eastward propagation processes from Tibetan Plateau and MCSs embedded in these cloud clusters
摘要点击 278  全文点击 138  投稿时间:2018-05-31  修订日期:2018-11-29
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基金:  国家自然科学基金
中文关键词:  高原云团东传过程,下游地区降水,东传过程MCS,统计特征
英文关键词:  cloud clusters’ eastward propagation process from TP, rainfall downstream, MCS embedded in the eastward cloud clusters, statistical characteristic
  
作者中文名作者英文名单位
王婧羽Wang Jingyu中国气象局武汉暴雨研究所
引用:王婧羽.2019.青藏高原云团东传过程及其中MCS统计特征[J].大气科学
Citation:Wang Jingyu.2019.The statistical characteristics of the cloud clusters’ eastward propagation processes from Tibetan Plateau and MCSs embedded in these cloud clusters[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      利用逐小时风云卫星TBB资料、逐小时中国自动站与CMORPH降水产品融合数据以及国家级地面观测站24小时累积降水量,统计分析2010-2016年夏季,伴随下游地区(104°E以东)降水的青藏高原云团东传过程以及东传过程中镶嵌于云团中的中尺度对流系统(Mesoscale Convective System,简称MCS)特征。结果表明,共出现120次伴随下游降水的高原云团东传过程,6月出现最频繁,但持续时间较长的过程多出现在7月。云团主要沿平直东传、沿长江折向东传和复合东传三条路径向东传播。其中路径二——沿江折向东传中的过程是高影响过程:因为过程次数较多(46次),过程平均持续时间较长(62小时),在下游地区引发的降水日数和暴雨日数最多。东传过程MCS在7月形成最多,集中分布在青藏高原东坡、云贵高原东部、长江沿岸及其以南地区。高原MCS影响长江中下游地区降水主要是通过向东传播的形式实现,因为即使生命史更长的中α尺度对流系统(Meso-α Convective system,简称MαCS)也鲜少直接移动至110°E以东地区。不同区域的中α尺度持续性拉长形对流系统(Permanent Elongated Convective System,简称PECS)的日变化特征显示,东传过程MCS更容易在夜间从高原东坡向东传播至下游地区。在三条路径中,路径二中的东传过程MCS数量最多、在下游地区发展最旺盛并与降水日数和覆盖范围存在更好的对应关系。
Abstract:
      Based on the TBB data from FY2E (2010-2014) and FY2G (2015-2016), the gauge-adjusted CMORPH hourly precipitation and gauge observed daily rainfalls, the statistical characteristics of the cloud clusters’ eastward propagation processes from TP and Mesoscale Convective Systems (MCS) embedded in theses cloud clusters in summer of 2010-2016 are analyzed. The results show that, there are 120 eastward propagation processes with precipitation over downstream region (east of 104°E), they occur most in June but those with longer duration occur more in July. Cloud clusters picture three prominent propagation tracks from TP to middle-lower reaches of Yangtze River basin: 1.propagating eastward directly, 2.propagating along the Yangtze River that cloud clusters propagate southeastward first then turn eastward and 3.complex propagation processes. Processes in second track are high impact processes according to high frequency (46 processes), long duration and most rainy days (heavy rain days) over the downstream region. The MCSs embedded in these eastward cloud clusters occur most in July and more frequently over east slope of TP, east part of Yunnan-Guizhou Plateau and Yangtze River basin. The MCSs over TP mainly propagate east to affect the rainfall over downstream region because longer-lived Meso-α Convective Systems (MαCS) with longer moving tracks over TP or east slope of TP cannot directly move to the region east of 110°E. The diurnal cycles of Permanent Elongated Convective System (PECS) over different regions show that they propagate downstream more easily at night. The MCSs embedded in the cloud clusters which belong to the processes in second track are most, strongest and are associated with heavy rainfall over downstream region more consistently.
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