梅雨锋上中尺度低涡的发展及其动能变化

THE DEVELOPMENT OF MESO-β SCALE VORTEX ON THE MEIYU FRONT AND ITS ENERGY CONVERSION

本文研究了1980年7月31日至8月1日的暴雨中尺度低涡的发展过程及结构特征,发现低涡的斜压性清楚,风场和热力场均不对称,暖湿区內上升运动最强?怨δ芊匠痰难芯勘砻?在其发展过程中散度风动能向旋转风动能转换,尤其在低层更为清楚,决定因子是f▽x▽Ψ项;在涡旋发展时,涡度场与散度场的配置使▽x·▽Ψ达到最大。

A vortex with heavy rainfall typical of disturbance over the Meiyu front occurred in the period of July 31 to August 1, 1980 The development and structure characteristics of this meso-β scale low are studied. The low bears clear baroclinity with the front structure different from heat lows in the area. The wind velocity and thermodynamic fields of the low are asymmetric with the strongest ascending motion at its warm sector. Based on the formula K=K_ψ+K_χ-J(ψ, Χ), we have calculated the kinetic energy of the divergent and rotational parts of the winds and their conversion. Investigation of the kinetic energy feature of the low suggests that the transfer from K_χ to K_ψ occurs in its whole life cycle, especially in lower levels. The terms of f▽ψ·▽χ and ▽~2ψ·▽ψ·▽χ play a mojor role in the conversion similar to the situation in explosive cyclogenesis.