【摘要】 利用常规观测资料、卫星云图和NCEP全球分析资料(FNL),对2010年8月13日豫北沿黄地区出现的短时强降水过程进行了诊断分析。结果表明:这次强降水过程是在低槽东移、副高东退南压的形势下,由高、低空急流,中低层切变线,以及地面倒槽和弱冷空气等影响系统共同作用造成的。强降水发生时暴雨区低层水汽辐合跃增,配合强劲的垂直上升运动,在暴雨区上空建立深厚的湿层。过程前期的副高控制为强降水的发生积聚了大量的不稳定能量,强降水区正好位于低层能量锋区的南侧,同时CAPE值的锐减时段对应着最强降水时段。低层弱的干冷空气侵入是本次暴雨过程产生的重要触发机制,高层干冷空气的侵入有利于干层的形成和维持,干层的存在加强了对流不稳定性,对暴雨的加强和发展起重要作用。强降水过程中低层正的垂直螺旋度演变趋势与强降水的落区和降水强度变化有较好的对应关系。垂直螺旋度中低层正中心、高层负中心,这种上下耦合的结构特点对系统自身的发展及暴雨的维持十分有利。更多还原

【Abstract】 By using routine observational data,satellite cloud image and the FNL data of NCEP,the rainstorm event over northern Henan along the Yellow River on 13 August 2010 is analyzed.The result shows that the heavy rains is affected directly by the Western Pacific Subtropical High(WPSH) when it interacts with mid-latitude though in addition to upper and lower-level jets,the shear line of middle and lower layer,ground though,and invasion of weak cold air.In heavy rain area the lower water vapor rapidly jump as the heavy rain happens.With the strong vertical ascending motion the deep moisture layer is established over the heavy rain area.Before the event plenty of instability energy has been accumulated for the control of the subtropical high and the heavy rain area is located just south of energy frontal zone of low layer.The plummeted time of CAPE value corresponds to heavy rainfall time.Weak dry cold air from the north at the low layer is the important trigger mechanism of the heavy rain.The invasion of dry cold air at upper layer is useful to the formation and maintenance of dried air layer which strengthens the convection instability and plays an important role in the strength and development of the heavy rain.During the heavy rainfall the variation trend of positive vertical helicity of mid-low layers has a good corresponding relationship with heavy rain area and precipitation intensity.The allocation of positive center at the mid-low layers and negative center at the upper layers is useful to the development of the system and the continuation of heavy rain.更多还原