暴雨系统中的非平衡运动与有限区域模式的初值化

将非平衡风分成两部分:(1)非平街风的旋度部分(?)′_R和(2)非平衡风的散度部分(?)′_D。在产生暴雨的次天气尺度系统中,这两种非平衡风具有同样重要的作用。所以在有限区域细网格模式的初值化中,不能只考虑散度风,即使用通常称为“散度初值化”的方案,而且要考虑非平衡风的旋度部分。根据散度方程分析,(?)′_R是维持、调整散度场的重要因子。试验了三种风场初值化方案,结果表明,在风场初值中同时考虑(?)′_R和(?)′_D,可以明显改善模式的降水预报。

The non-balance motions in the heavy rainstorm and the initialization of the limited area model

The non-balance wind (difference between real and balance winds) is decomposed, into divergent and rotational components. The dynamical impacts of these two components on the development of heavy rainstorm are analysed. It is found that the rotational part plays a role in maintenance of the divergent field.Three experiments with differential initialization methods are carried out by using a 5 level limited area model. The precipitation forecast is improved if both the divergent and rotational components are included in the initial wind field.