垂直运动研究进展及新型垂直运动方程

Advancements in the Study of Vertical Motion and New Vertical Motion Equations

垂直运动在天气系统(尤其是中小尺度系统)发生发展过程中有极其重要的作用,本文回顾并小结了大气垂直运动方程的研究进展。在质量守恒前提下,垂直运动可由连续方程积分计算得到,这个算法需要准确计算散度,不容易实现。基于大气绝热假设的绝热法,由于与实际天气过程热力变化有较大差别,计算的垂直运动也不准确。垂直运动的诊断与天气系统尺度有关。大尺度系统以涡旋运动为主,满足准水平,不必要过多考虑浮力和风切作用。因此,出现了准地转条件的垂直运动方程,且在大尺度运动中应用较好。中尺度系统运动中,辐合辐散运动与旋转运动同等重要,垂直运动不能忽略,垂直运动方程在形式上要复杂一些,但其强迫项仍是由涵差的涡度平流及温度平流的拉普拉斯所构成,本质与大尺度系统中的ω方程没有太大差别。小尺度强风暴运动以辐合辐散为主,浮力及风切起着主导作用,其垂直运动方程要复杂得多。但是,由于任何小尺度强对流系统都是在大中尺度背景下发生的,所以背景场强迫的垂直运动仍然存在,完整的垂直运动应考虑不同天气尺度系统调整产生的垂直速度,应联立垂直运动方程组进行计算。本文提出的多效应的新型垂直运动方程,可以较为准确地实现强对流运动中的垂直速度的诊断。

This article provides a comprehensive review of the research progress on atmospheric vertical motion equations,which are crucial for the formation and development of weather systems,particularly small and medium-scale systems.Vertical motion can be calculated by integrating continuity equations that conserve mass,but this method requires the accurate computation of divergence,which is challenging to implement.The adiabatic method for calculating vertical motion is also imprecise,as the underlying assumption of adiabatic internal atmospheric changes does not align with actual thermal variations in the atmosphere.Vertical motion diagnosis is associated with atmospheric scales,and large-scale systems are primarily governed by vortex motion,adhering to quasi-horizontal motion.Such systems often give little consideration to buoyancy and wind shear effects.Consequently,a vertical motion equation that incorporates the first law of thermodynamics,the atmospheric state equation,hydrostatic equilibrium,and quasi-geostrophic conditions is better suited for large-scale motion applications.The equation for vertical motion in mesoscale systems is more complex owing to the equally significant relationship between convergent or divergent motion and rotational motion.Additionally,vertical motion cannot be disregarded.However,the forcing term still consists of vorticity advection variations with height and the Laplacian of temperature advection,which is fundamentally similar to theωequation in large-scale systems.In strong small-scale storm motions,convergent and divergent motions are predominant,with buoyancy and wind shear playing critical roles,making the equation for vertical motion even more intricate.Nonetheless,vertical motion forced by the background field persists,as strong small-or medium-scale convective systems cannot occur independently from large-or medium-scale background fields.Consequently,a comprehensive vertical motion analysis should consider the vertical velocity generated by the adjustment of weather systems across different scales.This implies that a combination of vertical motion equations should be used for calculations.The novel vertical motion equation incorporating multiple effects can enhance the precision of diagnostic analysis of vertical velocity in small-scale,strong convective systems.