凉山州区域性暖区暴雨特征及环流分型研究

Study on the Characteristics and Circulation Classification of Regional Rainstorm in Warm Sector in Liangshan Prefecture

选取2013—2022年4—10月凉山州降水数据,结合常规地面观测、高空观测和NCEP再分析资料,制定了凉山州区域性暖区暴雨的统计标准,并对筛选出的42例区域性暖区暴雨进行统计分析和天气学诊断。结果表明:根据天气形势和主要影响系统,凉山州区域性暖区暴雨可分为西南低涡型、冷切变型、暖切变型、西南风型、东南风型5类,其中西南低涡型最多,东南风型最少。各类区域性暖区暴雨都具有短时强降水特征,强降水均出现在傍晚到夜间,白天降水强度减弱。西南低涡型常出现在低涡中心或外围东南侧,降水成片集中,易出现小时雨量≥50 mm的极端强降水。冷切变型常出现在冷切变线东南侧。暖切变型常出现在暖切变线东北侧。西南风型降水成片集中且范围广,多出现在低层一致的西南气流带中,在风速辐合区及脉动区尤为常见。东南风型降水较分散,易出现在山脉迎风坡。东南风型的水汽主要来源于南海和热带西太平洋,其余4类的水汽主要来源于孟加拉湾。5类区域性暖区暴雨均发生在高能高湿的不稳定层结中,配合有较强的垂直上升运动。西南风型、西南低涡型及东南风型的各物理量平均值均优于冷切变型和暖切变型,以西南风型各物理量整体配置更优。

Based on the precipitation data from April to October during 2013—2022,combined with conventional ground observation,upper-air observation and NCEP reanalysis data,the statistical analysis of the regional warm-sector rainstorm in Liangshan Prefecture were carried out,and 42 cases of regional warm-sector rainstorm were selected for statistical analysis and synoptic diagnosis.The results show that according to the weather situation and main influence systems,the regional warm-sector rainstorm in Liangshan Prefecture can be divided into five types:southwest vortex type,cold shear type,warm shear type,southwest wind type and southeast wind type.Among them,the southwest vortex type is the most,and the southeast wind type is the least.All kinds of regional warm-sector rainstorms have the characteristics of short-term heavy precipitation.The heavy precipitation occurs from evening to night,and the precipitation intensity decreases during the day.The southwest vortex type often appears in the center of the vortex or the southeast side of the periphery,the precipitation is concentrated,and the extreme heavy rainfall with hourly rainfall≥50 mm is easy to appear.The cold shear type rainstorm often appears in the southeast of cold shear line,the warm shear type rainstorm often appears in the northeast of warm shear line.The southwest wind type rainstorm is concentrated and wide,mostly in the low-level consistent southwest airflow zone,which is particularly common in the wind speed convergence zone and the pulsation zone.The water vapor of the southeast wind type rainstorm mainly comes from the South China Sea and the tropical western Pacific Ocean,and the water vapor of the other four types mainly comes from the Bay of Bengal.The five types of warm-sector rainstorm all occur in unstable stratification with high energy and high humidity,with the strong vertical upward movement.The average physical quantities of southwest wind type,southwest vortex type and southeast wind type are better than those of cold shear type and warm shear type,and the overall configuration of physical quantities of southwest wind type is better.