暴雨过程环境涡散场能量转换特征

The Characteristics of Conversion between Kinetic Energies ofDivergent Winds and Non - Divergent Winds duringHeavy Rain Period

本文计算和讨论4个不同类型暴雨过程各层次时空平均涡散场能量转换函数.指出其基本特征为:(1)对流层下层为最大正转换层,其转换强度和方向受C1+C2项制约,当暴雨发展时,能量转换急剧增长;而对流层上层的负转换强度则受控于C3项.但就对流层整层而言,能量转换函数C(K_χ,K_Ψ)均为正值,即势流动能向涡流动能转换,促使暴雨系统的维持和发展.(2)能量转换函数的水平分布,在对流层下层其正转换区与过程降水区较为一致,而在对流层上层的负转换区则位于过程降水区的北侧.

This paper calculates and discusses the temporal - spatial averaged conversion function between divergent winds and non - divergent winds' kinetic energy C (Kx, Kψ) for four kinds of heavy rain processes. The main results are as follows.(1) The layer of the maximum positive conversion is found in the lower troposphere. The intensity and direction of the positive conversion are restricted by terms C1+C2, while the intensity of the negative conversion in the upper troposphere depends on the term C3. However the kinetic energy of divergent winds is changed into the kinetic energy of non - divergent winds for the whole troposphere, thus leading to the maintenance and development of heavy rain.(2) The horizontal pattern of positive conversion regions in the lower troposphere is in good coincidence with that of the accumulated rainfall region, while the negative conversion region in the upper troposphere is located at the northern flank of the accumulated rainfall.