Journal of Arid Meteorology ›› 2021, Vol. 39 ›› Issue (4): 641-651.

Previous Articles     Next Articles

Comparison of Dynamic Characteristics of Two Short-time Heavy Precipitation Processes of Baroclinic-Frontogenesis in the Early Flood Period of Southeast Gansu

XIAO Wei1, FU Zhao1, XU Lili1, LIU Weicheng1,DI Xiaohong1, ZHENG Xin2, YANG Xiumei1   

  1. (1. Lanzhou Central Meteorological Observatory, Lanzhou 730020, China;
    2. Lanzhou Meteorological Bureau of Gansu Province, Lanzhou 730020, China)


  • Online:2021-08-31 Published:2021-09-13

陇东南汛前期2次斜压锋生类短时强降水过程动力特征对比

肖玮1,傅朝1,徐丽丽1,刘维成1,狄潇泓1,郑新2,杨秀梅1   

  1. (1.兰州中心气象台,甘肃兰州730020;2.甘肃省兰州市气象局,甘肃兰州730020)
  • 通讯作者: 傅朝,男,正研级高级工程师,主要从事强对流天气预报及研究工作. E-mail: dry52889@hotmail.com。
  • 作者简介:肖玮(1983— ),女,甘肃陇南人,工程师,主要从事天气预报工作. E-mail: weiweir1983@126.com。
  • 基金资助:
    甘肃省气象局创新团队项目(GXQXCXTD-2020-01)和甘肃省气象局气象研究型业务与科研项目(Ms2021-13)共同资助

Abstract: Abstract: The two regional shorttime heavy precipitation processes occurred in southeastern Gansu on April 19-20, 2019 (hereinafter using abbreviation “4·19”) and on April 26-27, 2019 (hereinafter using abbreviation “4·26”). Based on the conventional meteorological observations and ERA5 reanalysis data, the dynamic characteristics of two processes were analyzed through the diagnosis of physical quantities including frontogenesis function, temperature advection and vertical wind shear. The results are as follows: (1) The two processes belonged to baroclinicfrontogenesis severe convection, in which cold advection existed in the upper air, cold and warm air converged in low level, and obvious cold fronts and cold shear lines existed on the ground. (2) Under the same significant baroclinic atmospheric conditions, the dynamic characteristics of the two processes were significantly different. “4·19” process presented the characteristics of frontal precipitation, in which the cold air was relatively deep, strong and cold advection in the middle and low layers drove the lowlevel frontogenesis, and convection occurred under the dynamic unstable conditions forced by uplift of the front. However, “4·26” process had obvious characteristics of convective precipitation, in which cold air was diffused in the lower and near ground layers, and convective activity occurred under the combined action of near ground layer frontogenesis and lowlevel jets, and it was dominated by thermal instability. (3) The frontogenesis functions on 700 hPa and 850 hPa could quantitatively describe the temporal and spatial distribution and evolution characteristics of affecting systems in the lowlevel and near ground layer. Since the near ground layer trigger system was difficult to define due to the influence of terrain, especially in “4·19” process the pathes of cold air in the lower layer and near ground layer were complicated, the frontogenesis function could be used as a physical quantity index for the near ground layer trigger system.


Key words: short-time heavy precipitation, baroclinic frontogenesis, dynamic characteristics, frontogenesis function

摘要: 2019年4月19—20日(简称“4·19”)和4月26—27日(简称“4·26”)陇东南出现2次区域短时强降水天气过程,利用常规气象观测资料和ERA5再分析资料,通过诊断锋生函数、温度平流、垂直风切变等物理量对2次过程的动力特征进行对比分析。结果表明:(1)2次过程均存在高空冷平流、低层冷暖气流交汇,地面分别有明显的冷锋和冷式切变辐合线,属于斜压锋生类强对流。(2)在同样显著的斜压大气环境条件下,2次过程动力特征存在明显差异,“4·19”过程冷空气较为深厚,中、低层强冷平流驱动低层锋生,对流发生在锋面强迫抬升的动力不稳定条件下,呈现出锋面降水特征;“4·26”过程低层及近地层有冷空气扩散,对流发生在近地层锋生与低空急流共同作用下,由热力不稳定主导,对流性降水特征显著。(3)700 hPa和850 hPa锋生函数可分别定量描述低层和近地层影响系统的时空分布和演变特征,由于近地层触发系统受地形影响难以界定,尤其“4·26”过程低层及近地层冷空气路径复杂,锋生函数可作为近地层触发系统判定的物理量指标。

关键词: 短时强降水, 斜压锋生, 动力特征, 锋生函数

CLC Number: