Journal of Arid Meteorology

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Statistical Characteristics of Mesoscale Convective Systems over the Middle Reaches Area of the Yellow River During 2005-2014

  

  1. 1. Shanxi Meteorological Observatory, Taiyuan 030006, China;
    2. China Meteorological Administration Cadres Training Institute, Beijing 100081, China
  • Online:2016-12-30 Published:2016-12-30

黄河中游地区中尺度对流系统的统计特征

  

  1. 1.山西省气象台,山西 太原 030006;
    2.中国气象局干部培训学院,北京 100081
  • 作者简介:赵桂香(1965- ),女,硕士,正研高工,主要从事灾害天气预报和气候分析技术研究. E-mail: liyun0123@126.com
  • 基金资助:

    国家自然科学基金项目“黄河中游地区突发性大暴雨MCC结构特征研究”(41475050)资助

Abstract:

Based on the hourly TBB and cloud images of FY-2E, meteorological observation data, and NCEP reanalysis data with 1°×1° spatial resolution from May to October during 2005-2014, the climatic characteristics of mesoscale convective systems (MCS) over the middle reaches area of the Yellow River were analyzed, including mesoscale convective complex (MCC), persistent elongated convective systems (PECS), meso-βscale MCC (MβCCS) and meso-βscale PECS (MβECS). The results are as follows: (1) MCS tended to occur over the middle and south of Gansu, the middle and south of Shanxi, the middle and north of Shaanxi, and the border of Shanxi, Shaanxi and Inner Mongolia. MCS over the middle reaches area of the Yellow River formed from May to October, and was easy to develop the mature in summer. MCC and MβECS were main MCS causing precipitation in summer. (2) The daily variation of MCS was obvious, and usually formed and matured in the afternoon and the evening to early morning of the next day. Most MCS generated fast and dissipated slowly, and were mainly move to the easterly and southeasterly, but the moving of round shape MCS was less than the elongated shape’s. (3) The average TBB for the round shape MCS was lower than the elongated shape MCS. The development of MCC was most vigorous and strong, and it was the strongest in August, while that of MβECS wasn’t obviously influenced by the seasonal change. The average eccentricity of the mature MCC and PECS over the middle reaches area of the Yellow River were greater than that in USA, and the former was greater than in the lower reaches area of the Yellow River, while the latter was smaller. (4) The characteristics of rainfall caused by MCS were complex over the middle reaches area of the Yellow River, and there were obvious regional differences. There was wider, stronger and longer precipitation when the multiple MCS merged. The rainfall in the center of cloud area was obviously greater than in other region of cloud area. The heavy rain mainly occurred in the left and backward quadrant of MCS. The most precipitation intensity of MCS was generally greater than 50 mm·h-1. The ratios of rain areas and cloud areas for the different types and regions MCS were significantly different. (5) There were obvious inter-annual variation characteristics of MCS. The number of MCS was more in 2011 and less in 2009 than the normal year, and the circulation situation in 2011 was nearly opposite to 2009, which were related not only to the subtropical high, geopotential height anomaly on 500 hPa in the middle latitude and transportation and gather of warm and moisture airflow in lower layer but also to the cold vortex systems on 500 hPa.

Key words:  MCS, the middle reaches of the Yellow River, statistical characteristics, difference

摘要:

利用2005—2014年逐时FY-2E卫星资料、实况观测资料和NCEP再分析资料,采用统计方法对黄河中游地区中尺度对流系统(MCS)的特征进行了分析,包括中尺度对流复合体(MCC)、持续拉长状对流系统(PECS)、β中尺度对流复合体(MβCCS)和β中尺度持续拉长状对流系统(MβECS)等4类。结果表明:(1)甘肃中南部、山西中南部和陕西中北部以及蒙、晋、陕3省(区)交界处为MCS高发区;一年内5—10月均有形成,夏季更易发展成熟,MCC和MβECS是该区影响夏季降水的主要MCS。(2)MCS具有明显的日变化特点,多成熟于午后或傍晚到次日凌晨;大多数MCS表现出生成快、消亡慢的特点,其移动方向以偏东和偏东南方向为主,且圆形状的较拉长状的移动少。(3)圆形状的MCS的平均TBB较拉长状的低,其中MCC发展最旺盛、强烈,且8月最强,而MβECS的发展受季节影响不大。成熟时的平均离心率,MCC和PECS较美国的偏大;与黄河下游地区相比,MCC偏大,PECS则偏小。(4)MCS造成的降水特征复杂,地域差异明显,多个合并后的对流系统造成的降水范围更大、强度更强、持续时间更长;暴雨主要出现在左后象限,最大雨强出现在成熟阶段,一般>50 mm·h-1;生成于不同区域、不同类型的MCS,其雨区和云区面积比的差异较大。(5)MCS具有明显的年际变化特点,其中最多年2011年和最少年2009年的环流形势表现出几乎相反的特点,除与副热带高压、500 hPa中纬度位势高度距平、低层暖湿气流输送和聚集等有关外,还与500 hPa冷涡活动密切相关。

关键词: MCS, 黄河中游, 统计特征, 差异

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