主办单位：中国气象局沈阳大气环境研究所
国际刊号：ISSN 1673-503X
国内刊号：CN 21-1531/P
气象与环境学报

气象与环境学报 ›› 2020, Vol. 36 ›› Issue (6): 21-30.doi: 10.3969/j.issn.1673-503X.2020.06.003

• 论文 • 上一篇    下一篇

2018年7月四川盆地降水异常特征及成因分析

何光碧1(),师锐2,曾波1   

  1. 1. 中国气象局成都高原气象研究所/高原与盆地暴雨旱涝灾害四川省重点实验室, 四川 成都 610072
    2. 四川省气象台, 四川 成都 610072
  • 收稿日期:2019-08-30 出版日期:2020-12-30 发布日期:2021-01-06
  • 作者简介:何光碧, 女, 1961年生, 正研级高级工程师, 从事高原天气与数值预报工作, E-mail:hegb_gaoyuansuo6@163.com
  • 基金资助:
    国家自然科学基金重点项目(91337215)

Characteristics and causes of abnormal precipitation in Sichuan Basin in July of 2018

Guang-bi HE1(),Rui SHI2,Bo ZENG1   

  1. 1. Institute of Plateau Meteorology, Chengdu, China Meteorological Administration/Sichuan Key Laboratory of Heavy Rain and Drought-Flood Disasters in Plateau and Basin, Chengdu 610072, China
    2. Sichuan Meteorological Observatory, Chengdu 610072, China
  • Received:2019-08-30 Online:2020-12-30 Published:2021-01-06

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摘要：

利用1961—2018年四川站点降水资料和NCEP/NCAR再分析资料，应用统计和天气学诊断方法，分析了2018年7月四川盆地降水异常特征、大气环流特征、异常降水期间水汽、低值系统与冷暖空气活动等对降水的影响。结果表明：2018年7月四川暴雨频繁出现，较气候均值降水异常偏多，表现在降水日数长、降水量增加显著，降水增加的区域主要在盆地西部。同时，降水异常偏多还表现在日最大降水量和连续降水日数显著增加，大雨量级降水、暴雨及以上量级降水的降水量和降水日数显著增加。大气环流与气候态相比，2018年7月更强、更暖、更偏东的南亚高压和更偏西、偏北的副热带高压，有利于青藏高原及其以东高层大气辐散，使得降水天气系统维持，水汽源源不断地输送到盆地，使得降水发生。2018年7月较气候态有更充沛的水汽聚集，异常水汽输送源地为南海和西太平洋，水汽沿副热带高压南侧输送，该水汽输送带与副热带高压异常偏北、偏西以及热带气旋活动密切相关。大气可降水量和水汽通量大值出现时段与降水过程有较好的对应。2018年7月降水期间，盆地低值系统活动频繁，低层为暖湿气流输送，中层为(弱)冷空气活动，有利于触发盆地降水。

关键词: 四川盆地, 环流特征, 副热带高压, 水汽输送

Abstract:

To reveal the characteristics and causes of abnormal precipitation in the Sichuan Basin in July of 2018, we analyzed the characteristics of precipitation anomalies and atmospheric circulation, and the effect of water vapour, low system, and cold/warm air masses on precipitation based on statistical method and synoptic diagnostic methods and using precipitation data at meteorological stations and National Centers for Environmental Prediction (NCEP)/National Centers for Atmospheric Research (NCAR) reanalysis data from 1961 to 2018.The results show that rainstorms occur frequently over the Sichuan Basin in July of 2018, which results in anomalously higher precipitation compared with the climate mean state.The abnormal precipitation is characterized by more precipitation days and higher precipitation amounts, especially concentrating in the western basin.Meanwhile, the maximum daily precipitation and continuous precipitation day numbers both increase markedly, as well as the amount and day numbers of over heavy precipitation and rainstorm.Compared with the mean state of atmospheric circulation, the South Asia High is stronger and warmer and moves eastward, and the Subtropical High moves westward and northward in July of 2018, which are beneficial for the divergence of upper-level air over the Tibetan Plateau and its eastern areas.This results in the maintaining of precipitation weather systems and the transport of abundant water vapor to the basin.More water vapor is concentrated in July of 2018 compared with the mean state, coming from the South China Sea and the West Pacific Ocean.Water vapor is transported along the southern side of the Subtropical High, which is closely related to the anomalous northward and westward movement of Subtropical High and tropical cyclones.The period of high precipitable water vapor and high water vapor flux corresponds well with the precipitation process.Low system occurs frequently during precipitation events in July of 2018, with low-level warm and moist flows and middle-level (weak) cold airs, which favors triggering precipitation in the Sichuan Basin.

Key words: Sichuan Basin, Circulation characteristics, Subtropical high pressure, Water vapor transport

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