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近43 a影响浙江和引发区域性暴雨的大气低涡统计特征

Statistical analysis of atmospheric vortexes affecting Zhejiang and causing regional rainstorms nearly 43 years

  • 摘要: 利用1979—2021年美国国家环境预测中心气候预测系统再分析资料和浙江省历史降水资料,采用大气低涡客观识别和追踪算法,统计分析了近43 a影响浙江和引发区域性暴雨的大气低涡气候特征。结果表明:(1) 影响浙江的大气低涡主要位于安徽中东部、江西东北部和江苏中南部;活跃于4—6月,以6月频数最多;夜间至清晨的大气低涡易影响浙江,且更易引发区域性暴雨,但生命史较短。(2) 引发浙江区域性暴雨的大气低涡统计特征与影响浙江的大气低涡类似,大气低涡在夏季(6—8月)最易引发区域性暴雨。(3) 大气低涡引发浙江区域性暴雨天气时,浙江多位于高空浅槽前部、低层高能量区,受大气低涡东侧暖式切变线影响,源自南海的西南气流向浙江输送水汽。(4) 梅雨期的6月大气低涡强度强、浙江省内温度经向梯度、西南风速大,大气低涡引发的区域性暴雨降水主要位于浙江西部以暴雨为主;西太平洋副热带高压峰期的8月,大气低涡引发的区域性暴雨降水主要在浙江东南沿海以分散性大暴雨为主。

     

    Abstract: Based on the reanalysis data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis and historical precipitation data from Zhejiang Province, characteristics of vortexes that have affected Zhejiang and induced regional heavy rainstorms over the past 43 years are statistically analyzed with the objective identification and tracking algorithm. The results are as follows. Firstly, low vortexes affecting Zhejiang are mainly located in the middle and east of Anhui, the northeast of Jiangxi, and the middle and south of Jiangsu. They are usually active from April to June, with the highest frequency in June. Vortexes from night to early morning are more likely to affect Zhejiang, and cause regional heavy rainstorms, but the lifetime of these rainstorms tends to be short. Secondly, the statistical characteristics of vortexes inducing rainstorms in Zhejiang are similar to those affecting Zhejiang. The low vortexes are most likely to cause regional rainstorms in summer (June to August). Thirdly, when vortexes cause regional rainstorms, Zhejiang is usually located in front of the upper shallow trough, and the low-level high-energy region. Affected by the warm shear line on the east side of the vortexes, the southwest warm and wet airflow from the South China Sea continuously transports water vapor to Zhejiang. Finally, in June during the Mei-yu season, the intensity of vortexes is strong, and the temperature meridian gradient and the southwest wind speed on the south side of vortexes are large. The regional rainstorm precipitation induced by vortexes is mainly located in the west of Zhejiang and is dominated by heavy rainfall. In August during the western Pacific subtropical high period, the regional rainstorm precipitation induced by the vortex is mainly in the southeast coastal area of Zhejiang, and characterized by scattered heavy rainfall.

     

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