| 季风低压诱发2018年8月广东特大暴雨过程分析 |
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| 引用本文： | 黄玉蓉,黄绮君,郭炳瑶,葛旭阳,陈明诚.季风低压诱发2018年8月广东特大暴雨过程分析[J].大气科学学报,2024,47(1):95-107. |
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| 作者姓名： | 黄玉蓉 黄绮君 郭炳瑶 葛旭阳 陈明诚 |
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| 作者单位： | 南京信息工程大学 气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心, 江苏 南京 210044 |
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| 基金项目： | 国家自然科学基金资助项目(U2342202;42175003) |
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| 摘 要： | 利用NCEP/FNL再分析资料和中尺度数值模拟方法探讨2018年8月27日—9月1日季风低压环境下广东特大暴雨过程的形成成因。利用扰动天气图方法分析发现，季风低压和西南急流为此次广东暴雨过程提供了有利的水汽条件和能量条件。熵变零线位置与降水落区位置有较好的对应，零线处能量有最大累积，有利于暴雨的发生发展，对预报暴雨降水落区有一定的指示意义。为进一步验证季风低压的影响机制，构建不同季风低压尺度的敏感性试验，即通过滤去季风低压环流中的扰动分量来改变季风低压的强度。结果表明：暴雨强度与季风低压尺度和强度存在密切的关系。当季风低压强度较强时，暴雨过程总雨量强；当季风低压强度较弱时，降水大为减少甚至无降水。诊断分析指出，能量螺旋度指数能够较好反映出不同情形下降水发生发展，在季风低压背景下，暴雨区能量螺旋度指数较大，降水强度较强。反之，随着季风低压强度减弱，能量螺旋度指数减小，降水减弱。
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| 关 键 词： | 季风低压 暴雨 能量螺旋度 水汽条件 |
| 收稿时间： | 2021/4/15 0:00:00 |
| 修稿时间： | 2022/3/18 0:00:00 |
Analysis of a rainstorm associated with monsoon depression in Guangdong |
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| HUANG Yurong,HUANG Qijun,GUO Bingyao,GE Xuyang,CHEN Mingcheng.Analysis of a rainstorm associated with monsoon depression in Guangdong[J].大气科学学报,2024,47(1):95-107. |
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| Authors: | HUANG Yurong HUANG Qijun GUO Bingyao GE Xuyang CHEN Mingcheng |
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| Institution: | Key laboratory of Meteorological Disaster of Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China |
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| Abstract: | In this study,NCEP/FNL reanalysis and WRFV3.9.1 are used to investigate the influence of the intensity of the monsoon depression on the rainstorm process in Guangdong from 27 August to 1 September,2018.On August 27,the rainstorm was in the development stage,the precipitation distribution was relatively scattered,and the maximum value of the daily precipitation was 80 mm/day.Starting from August 28,the heavy rainfall was concentrated and tended to shift southward to the Pearl River Delta region,with a maximum daily precipitation exceeding 100 mm/day.The rainstorm reached a mature phase between 29 and 30 August,with a maximum of daily precipitation more than 200 mm/day,and the location of the precipitation area was concentrated in the southeast coastal area of Guangdong,with a northeast-southwest spatial distribution.On 31 August,the rainfall began to weaken,but the daily precipitation remained strong.Above all,this rainstorm process involved much precipitation,a long duration,and a concentrated area,making it a rare extraordinary heavy rainstorm event.Using the physical decomposition method indicates that the monsoon depression and low-level jet provided sufficient water vapor and energy for the rainstorm process.In the mature phase of the rainstorm process,there was a negative entropy anomaly to the south of the rainstorm area,and a positive one to the north.The zero line of entropy anomaly indicates that the tendency of entropy was zero,that is,the value of entropy reached its peak,which means that the accumulation of energy had a maximum value in this area.On the north side of the rainstorm,the increase of the entropy means that the unstable energy continued to grow,while the precipitation on the south side released the unstable energy,that is,the entropy decreased and tended to be stable.The location of the zero line of the entropy change corresponded closely with the spatial distribution of the precipitation.Energy accumulating at the zero line of the entropy change was favorable to the development of the rainstorm.To further verify the influence of the monsoon depression,sensitivity experiments (EXP_500,EXP_700,and EXP_1000) were constructed.Sensitivity experiments were conducted by filtering out the perturbation component in the monsoon depression to change the intensity of the monsoon depression.The results show that when the monsoon depression was strong,the rainstorm was likely to occur and the precipitation was strong,and when the monsoon depression was weak,the precipitation was reduced or even absent.The diagnostic analysis shows that the energy helicity had implications for the development of the rainfall:when the energy helicity was greater,the intensity of precipitation was stronger,and when the intensity of the monsoon depression weakened,the energy helicity decreased and the precipitation weakened. |
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| Keywords: | monsoon depression rainstorm energy helicity water vapor condition |
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