高级搜索

浙江低涡暴雨的环流分型及优选集合动力因子研究

Circulation classification and preferred dynamic factors of rainstorm induced by vortexes in Zhejiang

  • 摘要: 低涡是造成浙江区域性暴雨(简称低涡暴雨)的重要天气系统,为了解浙江低涡暴雨的大气环流分型及不同环流型的高相关集合动力因子,基于2016—2023年浙江及周边地区格点日降水量和NCEP-FNL再分析资料,利用多变量经验正交分解法(Multi-Variable Empirical Orthogonal Functions, MVEOF)及模拟退火算法和多元随机化技术相结合(Simulated ANnealing and Diversified RAndomization, SANDRA)的客观分型法对浙江44个低涡暴雨日的环流场进行分型,并优选不同环流型低涡暴雨的主要集合动力因子。结果表明,两种分型方法都将浙江低涡暴雨日分为暖区型、锋面型和回流型,以暖区型发生频次最多,锋面型次之,回流型最少。各环流型低涡多在浙江中西部造成降水,以整层一致西南风的暖区型低涡暴雨强度及落区最大。不同环流型造成浙江暴雨的外部条件不同。暖区型下,中尺度类的集合动力因子是低涡暴雨的优选因子;锋面型下,优选因子除包含中尺度类的因子外,低涡造成的大尺度水汽和垂直运动与暴雨发生也有较大关联;回流型下,中尺度类的因子相关性减弱,优选因子为大尺度散度相关量。

     

    Abstract: Atmospheric vortexes are important weather systems that cause regional rainstorm in Zhejiang, to investigate the atmospheric circulation patterns and highly dominant ensemble dynamic factors under different circulation types, we classify the circulation of 44 vortexes induced rainstorm days in Zhejiang based on daily precipitation in Zhejiang and surrounding areas, as well as NCEP-FNL reanalysis data, covering from 2016 to 2023. Classification is achieved using Multi-Variable Empirical Orthogonal Functions (MVEOF) combined with an objective typing method that integrates Simulated Annealing and Diversified Randomization (SANDRA). Additionally, we diagnose and select the primary ensemble dynamic factors contributing to the rainstorms under different circulation patterns. Results show that both classification methods categorize circulation of vortexes induced rainstorm days into three types: warm sector type, front type and return flow type, with warm sector type occurring most frequently, followed by the frontal type, and the return flow type being the least common. Under various circulation patterns, vortexes typically induce precipitation in central and western Zhejiang. The warm-sector type, characterized by consistent southwesterly winds throughout the atmosphere, produces the strongest rainstorm intensity and coverage. The diagnosis and selection of ensemble dynamic factors under different circulation patterns reveal that external conditions causing rainstorms in Zhejiang vary among types. For the warm sector type, mesoscale dynamic factors are the preferred factors; in the frontal type, in addition to mesoscale factors, large-scale water vapor and vertical motion induced by the vortexes also play a role; in the return flow type, the influence of mesoscale factors diminishes, while the role of large-scale divergence-related factors increases significantly.

     

/

返回文章
返回