发展与不发展南海扰动的能量收支与转换特征

THE DEVELOPED AND UNDEVELOPED TROPICAL DISTURBANCE IN SOUTH CHINA SEA SUMMER

关键词:  南海扰动  能量收支与转换  对比分析

Key words:  South China Sea disturbance  Energy budget and conversion  Contrast analysis

摘要:

选取夏季月份南海局地性扰动发展与不发展的个例各一个,利用动能收支方程分别考察了辐散风和旋转风的动能制造和输送对扰动发生发展的贡献,并计算了辐散风和旋转风之间的动能转换。结果表明,南海扰动发展成台风,次网格尺度效应是主要的动能源,积云对流的作用十分明显,虽然辐散风的动能制造以及辐散风和旋转风的通量辐合在台风发展各阶段均有不同程度的贡献,但都相对较弱;辐散风和旋转风动能间的转换C(K_χ,K_Ψ)随着扰动的发展而增强,而C(K_χ,K_Ψ)增强则主要是C1=f_χ·_Ψ的贡献,从C(K_χ,K_Ψ)的垂直分布来看,低层随着扰动的发展,K_χ向K_Ψ转换不断增强,使低层风速加大,高层在扰动的形成、发展和成熟时期则为负转换,对应的反气旋流出有利于扰动的进一步增强;此外,通过C(P,K_χ)从扰动形成到发展、成熟的各阶段,均有位能P向辐散风动能K_χ转换,最大转换层则出现在对流层中上层,C(P,K_χ)的强弱与C(K_χ,K_Ψ)的变化是基本一致的。

Abstract:

By selecting the developed and undeveloped tropical disturbances in South China Sea summer,we calculated the kinetic energy budget and conversion for the life cycle of disturbances.The results showed that sub grid scale cumulus convection plays an important role in the life cycle of developed disturbance.Apart from the contribution by cumulus convection,the horizontal flux item also has significant contribution to the development of disturbance in the initial stage.By investigating conversion function C(K_χ,K_Ψ),we examined the conversion feature between divergent wind and non divergent wind kinetic energy.It is found that C(K _χ,K_Ψ)increased with the development of disturbance,the principal contribution is C1=f_χ·_Ψ for the C(K_χ,K_Ψ).In lower troposphere,conversion from K_χ to K _Ψ,in upper troposphere,conversion from K _Ψ to K_χ.By investigating the conversion function C(P,K_χ),we examined the conversion feature between potential energy P and divergent wind kinetic energy.It is also found that C(P,K_χ) increased with the development of disturbance.The significant conversion occurred at upper troposphere.