汶川地震灾区暖区强降水的特征及环流分型研究

Analysis of the characteristics and environmental condition of the warm-zone torrential precipitation at the Wenchuan Earthquake-Damaged

利用2009-2018年加密自动站逐小时降水资料、常规观测资料和ERA Interim再分析资料,统计分析了汶川地震灾区31次暖区强降水个例的降水特征、环境条件和环流背景得出以下结论:暖区强降水落区与龙门山地形有密切的关系,暖区强降水主要发生在海拔高度500-1000 m的盆地与青藏高原过渡带上;暖区强降水有明显的日变化特征,主要出现在凌晨和午后两个时段,尤以凌晨时段最强;强降水是在高能高湿不稳定层结条件下,在沿高原边界层下滑的弱冷空气和山谷风环流的共同触发的对流性强降水;汶川地震灾区暖区强降水主要是在副热带高压型和鞍型场型两种大尺度环流背景下发生的。

The hourly rainfall of automatic stations,conventional observation data and ERA Interim reanalysis data form 2009 to 2018 were used to analyze the characteristics,meteorological elements and circulation features of 31 warm-zone torrential precipitation(WZTP)cases over the Wenchuan Earthquake-Damaged.The results areas follows.1)The WZTP happened in the transitional zone between Eastern slope of Tibet Plateau and Sichuan Basin(the altitude from 500 m to 1000 m).2)The WZTP have obviously daily variations,which mainly occurred in the early morning and afternoon,especially in the early morning.3)The WZTP is a strong convective precipitation which occurs and develops violently under the condition of high energy and high humidity unstable stratification,triggered by the weak cold air falling along the plateau boundary layer and the valley wind circulation.4)The large-scale circulation background that caused the heavy rainfall in the warm area of Wenchuan earthquake disaster area was mainly subtropical-high type and saddle field type.