2013年7月内蒙古东北部地区一次暴雨过程分析

Diagnosis Analysis of Severe Rainstorm in The Northeast of Inner Mongolia in July 2013

利用常规气象观测站、加密自动气象站和雷达监测资料,分析2013年7月27—28日内蒙古东部地区暴雨过程,结果表明,(1)副热带高压和鄂霍次克海低压稳定少动,使低压槽发展加强形成东北低涡,是暴雨过程的环流背景;(2)当副热带高压阻挡在内蒙古地区南侧,南方暖湿气流无法向北输送时,渤海湾水汽北抽和局地大气含水量充足是这次暴雨过程发生的必要条件;(3)在大气层结处于相对稳定情况下,当前期大气含水量极高时,即使多个对流指数值都显示未来不可能有强降水发生的情况下,暖空气下方的冷平流侵入会通过降温凝结的方式产生大量级降水;(4)在满足以上条件时,风场垂直切变的加强同样会带来短时强降水,但降水量小于冷平流凝结作用产生的强降水量。

Asevere rainstorm in the northeast of Inner Mongolia occurred in July 27-28th, 2013 is analyzed using routine observational data, automatic meteorologicalstation dataand radar data. The results show that,（1） the stably subtropical high and the Okhotsk low turn the pressure trough into the northeast cold vortex over the north of Inner Mongolia, and it is the background condition of this rainstorm,（2）the suffcient water vapor in the local atmosphere and from Bohai bay are the necessary condition of this rainstorm as the subtropical high blocks on the south of Inner Mongolia and the warm and moist air cannot be transported to the north from the south area. （3）although theatmospheric stratifcation is relatively stableand many convection indexes show that there can be no severe precipitation in the future, the cold advection below the warm air will produce heavy precipitation via moisture condensation if the water vapor in the atmosphere was suffcient in the early,（4）when the above conditions are met, the intensity of the very short-range severe precipitation caused by theenhancedvertical shear of wind is less than the precipitation brought by moisture condensationalong the cold advection.