近10年广东汛期不同类型的暖区暴雨发生环境场特征分析

Analysis of the Environmental Parameters of Warm-sector Heavy Rainfall in Different Types in Guangdong Province During Rainy Season in Recent 10 Years

关键词:  暖区暴雨  时空分布特征  环境参量  预警指标阈值  广东

Key words:  warm-sector heavy rainfall  spatiotemporal distribution  environmental parameters  warning threshold  Guangdong Province

摘要:

利用广东省国家基本气象站、区域自动站雨量数据和 ERA5 再分析资料，将 2013—2022 年近 10 年73次典型的广东暖区暴雨个例按环流特征分为四种类型：切变线型、低涡型、南风型和回流型，统计分析时空分布特征以及表征大气静力不稳定、水汽、能量和动力条件的物理量特征。（1）广东暖区暴雨中南风型发生频率最高，回流型最低。67% 的暖区暴雨发生在 5—6月，降水峰值时间 95% 出现在凌晨和白天，其中南风型特征最明显，72% 出现在早晨 05—08 时和午后 12—17 时。（2）不同类型暖区暴雨空间分布差异较大，回流型暖区暴雨降水中心为珠江口西侧，不同于其他三种类型均有 2 个主要落区。（3）不同类型暖区暴雨发生的关键环境参数表明，各种类型的暖区暴雨发生均不需要强的条件不稳定，500 hPa和 850 hPa温差阈值仅在 22 ℃左右；均需要充沛的水汽条件，其中回流型大气可降水量阈值最低，但仍达 52 mm；能量条件和动力条件不同类型阈值差异较大，回流型暖区暴雨所需的能量条件、低层风速更弱，但0~6km深层垂直风切变更强。

Abstract:

Based on the rainfall data of Guangdong National basic meteorological Stations, regional automatic stations and NCEP FNL reanalysis data, 73 typical warm-sector heavy rainfall cases in Guangdong during 2013-2022 were divided into four types according to circulation characteristics. They are shear line, low vortex, southerly wind, and backflow types. The characteristics of spatiotemporal distribution and physical quantities representing atmospheric static instability, energy, water vapor and dynamic conditions were analyzed statistically. The main results are as follows: (1) The southerly wind type has the highest frequency, and the backflow type has the lowest frequency. 67% of the warm-sector heavy rainfalls occur during May-June, with 95% of the peak precipitation time occurring in the early morning and daytime. The southerly wind type shows the most distinct variation, with 72% of cases occurring from 05: 00 to 08: 00 in the morning and 12: 00 to 17: 00 in the afternoon. (2) The spatial distribution of warm-sector heavy rainfall shows significant differences among different types. The center of the backflow type warm-sector heavy rainfall is located on the western side of the Pearl River Estuary, which differs from the other three types with two main precipitation zones. (3) The key environmental parameters different types of warm-sector heavy rainfall indicate that none of the types require strong conditional instability, and the temperature difference threshold between 500 hPa and 850 hPa is only about 22 ℃. All of them need abundant water vapor, with the precipitable water threshold for the backflow type being the lowest (50 mm). Significant differences exist in energy and dynamic condition thresholds among 4 types. The backflow type requires weaker energy conditions and lower-tropospheric wind speeds, but stronger vertical wind shear from surface to 6 km.