干旱气象 ›› 2022, Vol. 40 ›› Issue (4): 656-666.DOI: 10.11755/j.issn.1006-7639(2022)-04-0656

• 论文 • 上一篇    下一篇

西太平洋副热带高压控制下湖南一次短时强降水成因分析

兰明才1,2(), 周莉1,2(), 蒋帅3, 尹依雯3, 许霖1   

  1. 1. 湖南省气象台,湖南 长沙 410118
    2. 气象防灾减灾湖南省重点实验室,湖南 长沙 410118
    3. 湖南省岳阳市气象局,湖南 岳阳 414000
  • 收稿日期:2021-07-15 修回日期:2022-02-24 出版日期:2022-08-31 发布日期:2022-09-22
  • 通讯作者: 周莉
  • 作者简介:兰明才(1984—),男,高级工程师,主要从事天气预报预测及短时临近预报预警技术研究. E-mail: 372917798@qq.com
  • 基金资助:
    湖南省自然科学基金项目-青年基金(2022JJ40214);湖南省气象局研究型业务预报预测专项(XQKJ21C009);泛珠三角科技创新开放基金(FZSJ202104);2019年度湖南省重点领域研发计划项目(2019SK2161);2021年中国气象局创新发展专项(CXFZ2021J020);湖南省气象局2022年重点课题(XQKJ22A005)

Causes of a short-term heavy rainfall under the control of the western Pacific subtropical high in Hunan Province

LAN Mingcai1,2(), ZHOU Li1,2(), JIANG Shuai3, YIN Yiwen3, XU Lin1   

  1. 1. Hunan Meteorological Observatory, Changsha 410118, China
    2. Key Laboratory of Preventing and Reducing Meteorological Disaster in Hunan Province, Changsha 410118, China
    3. Yueyang Meteorological Bureau of Hunan Province, Yueyang 414000, Hunan, China
  • Received:2021-07-15 Revised:2022-02-24 Online:2022-08-31 Published:2022-09-22
  • Contact: ZHOU Li

摘要:

在天气预报业务中,发生在西太平洋副热带高压控制下的短时强降水容易出现漏报。为加深对西太平洋副热带高压控制下湖南短时强降水的认识,探究其成因和触发机制,本文利用地面自动站、多普勒天气雷达观测资料及FY-2F云顶亮温、NCEP再分析资料等,针对2018年9月6日一次西太平洋副热带高压控制下的湖南短时强降水成因开展研究。结果表明:在强盛的西太平洋副热带高压脊区内,丰沛的水汽、较强的不稳定能量及一定的抬升条件可触发短时强降水天气。正午前,受弱冷空气侵入影响,低层切变配合地面中尺度辐合线引起近地面动力抬升,从而触发对流性降水;午后,受太阳辐射影响,地面气温达到对流触发温度,从而触发热对流。正涡度区及低层辐合区在降水发生后都向上延伸,有利于垂直上升运动的维持,但较典型汛期强降水过程的动力条件明显偏弱。环境风及其垂直风切变小,且雷暴单体移动缓慢,有利于强降水在同一地区长时间维持。

关键词: 西太平洋副热带高压, 短时强降水, 水汽条件, 不稳定能量, 触发机制

Abstract:

In operational weather forecast, the short-term heavy precipitation under the control of the western Pacific subtropical high is easily to be missed. In order to get a better grasp of short-term heavy rainfall in Hunan under the control of the western Pacific subtropical high and explore its causes and trigger mechanism, this paper analyzes a short-term heavy rainfall process on September 6, 2018 by using the observation data from ground automatic weather station and Doppler weather radar, retrieved TBB (black body temperature) from FY-2F satellite and NCEP reanalysis. The results show that the abundant water vapor, stronger unstable energy and certain uplift conditions can trigger the short-term heavy rainfall in Hunan Province in the ridge of the strong western Pacific subtropical high. However, it is more difficult to forecast the rainstorm due to the lack of large-scale circulation systems such as trough, middle and low level jet and shear line. Due to the invasion of weak cold air before noon, the cooperation of low-level shear with surface mesoscale convergence line cause near surface dynamic uplift, further trigger convective precipitation. In the afternoon, the surface air temperature affecting by solar radiation reaches convective triggering temperature, which can trigger freely heat convection. Both the positive vorticity region and the low-level convergence region extend upward after the rainfall, which is conducive to the maintenance of vertical upward movement, but its dynamic condition is obviously weaker than that of typical heavy precipitation process in flood season. The environmental wind and its vertical shear are weak, and the thunderstorm cells move slowly, which is beneficial to the maintenance of heavy rainfall for a long time in the same area.

Key words: the western Pacific subtropical high, short-term heavy rainfall, water vapor condition, unstable energy, triggering mechanism

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