【摘要】 利用PSU/NCAR的高分辨率中尺度非静力数值模式MM5,模拟了2001年9月18日发生在青藏高原东侧的绵阳大暴雨过程。结果表明,高分辨率数值模式对触发本次降水过程的β中尺度对流系统具有较好的模拟能力。高分辨率模拟输出显示"9.18"绵阳大暴雨与边界层内一个中尺度辐合扰动的发展和移动相伴,且中尺度辐合扰动还诱发了一个时间尺度约为6h的β中尺度涡旋和强烈发展的降水雨团。模拟还显示受高原地形影响,该β中尺度对流系统具有独特的动力和热力结构。其动力特征是强上升运动和超强散度柱与对流层低层强涡度互耦发展,热力特征是对流层低层具有对流不稳定能量,中层具有斜压不稳定能量。中尺度对流系统具有两支上升入流和两支下沉出流,低层入流(东南气流)触发低层对流不稳定能量释放,中层入流(高原近地层偏西暖湿气流)触发中层大气斜压不稳定能量释放,两种不稳定能量共同作用促使对流雨团强烈发展,形成绵阳大暴雨。更多还原

【Abstract】 By use of PSU/NCAR mesoscale MM5, we have successfully simulated a heavy rainstorm process taking place in Mianyang, Sichuan Province on the east side of QinghaiXizang Plateau of Yangtze River on September, 18～19 2001 . The results show that the high resolution model has a better ability to simulate the mesoβscale convective system under the complex terrain of QinghaiXizang Plateau. Model outputs also indicate that "9.18" heavy rainstorm in Mianyang was accompanied with the development and movement of a mesoscale convergence disturbance in the lower troposphere. The dynamicalthermodynamic structural features of mesoβscale convective systemare: the extremely intensive ascendant motion and surpassing intensive divergence column with the strong vortex in lower troposphere is crosscoupling development, there is convective instability energy in the lower troposphere andbaroclinic instability energy in middle troposphere, which are very different from that of the middleandlowerreaches of Yangtze River.更多还原