湖北省两类典型极端降水过程气象因子异常特征对比

利用NCEP/NCAR再分析数据和其他常规观测数据,对湖北省两类典型极端降水型(南北气流汇合型、南北槽叠加型)的天气背景及气象因子异常特征进行分析,结果表明:南北气流汇合型500 hPa上形成南北气流汇合形势,低层切变线南侧南风发展异常强盛,地面上冷锋入暖槽形成静止锋,动力因子(850 hPa涡度、200 hPa散度)和水汽因子(大气可降水量)异常特征显著;南北槽叠加型500 hPa上形成南北槽叠加形势,低层或边界层形成显著低涡切变,地面上暖低压强烈发展,动力因子(200 hPa散度、925 hPa涡度)和不稳定因子(700 hPa温度平流)异常度比例偏高。最后给出了两类集天气背景与气象因子异常度配置于一体的极端降水天气概念模型。

Comparison of abnormal characteristics of meteorological factors in two typical extreme precipitation processes in Hubei Province

Based on the NCEP/NCAR reanalysis data and other conventional observation data, the abnormal characteristics of weather background and meteorological factors of two typical extreme precipitation types (north-south flow convergence type and north-south trough superposition type) in Hubei Province are analyzed. The results show that there is a convergence of the north and south airflow at 500 hPa for north-south flow convergence type. The southerly wind on the south side of the low-level shear line develops extremely strongly and the cold front on the ground enters the warm trough to form a stationary front. The dynamic factors (vorticity at 850 hPa and divergence at 200 hPa) and water vapor factor (atmospheric precipitable water) have significant abnormal characteristics. For north-south trough superposition type, the north and south troughs are superimposed at 500 hPa. There are significant vortex shear formed in the low layer or boundary layer, and the warm and low pressure on the ground develops strongly. The ratios of the abnormal degree of dynamic factors (divergence at 200 hPa and vorticity at 925 hPa) and instability factor (temperature advection at 700 hPa) are high. Finally, two conceptual models of extreme precipitation weather are presented, which combine the weather background and the abnormal degree of meteorological factors.