对称不稳定理论的天气分析与预报应用研究进展

Advances in synoptic analysis and application of symmetric instability theory

锋面降水、暴雨、暴雪、台风、飑线和爆发性气旋等灾害性天气的预报预警和倾斜对流发生发展机理的研究密切相关.在此研究领域,近年来国际间逐步发展起来的对称不稳定理论正在引起国内外气象学者的广泛关注.本文在介绍了对称不稳定理论的概念、天气学特征及计算分析方法的基础上,综述了国内外关于对称不稳定理论的研究和应用进展情况,提出了引起带状云和降水的倾斜对流发生发展机理和对称不稳定理论相关联的研究进展和存在问题.

Studies of the formation and development mechanism of the slantwise convection are critical to forecasting and warning of severe weathers, such as frontal precipitation, rainstorm, blizzard, typhoon, squall line, burst cyclone and so on. Recently, the developing theory of symmetric instability has attracted meteorologists＇ great attention in this field. Symmetric instability occurs when air parcel moves slantwise and upward with the effect of gravity （buoyancy） and inertial force, with vertically convective stability and horizontally inertial stability. It is the integrated embodiment and the continuous transition area of the convective instability and inertial instability. The symmetric instability can be qualitatively analysis by using image of Mg-θ vertical cross section and the synoptic elements such as the stream field, dynamics field, thermodynamics field and vertical motion field and so on, and it also can be quantitatively analysis with according to the parameters of slantwise convection available potential energy, potential vorticity, Richarson number and rise rate. In this paper, the advancement about the investigation and application of the symmetric instability has been summarized. Based on that, the formation and development mechanism of the slantwise convection which causes banded cloud and precipitation has also been introduced, as well as the research advancement and existing problems relating to the symmetric instability theory. The result shows that： （1） besides the need of the moist symmetric instability, water-vapor condition and lifting mechanism are also needed to motivate the slantwise convection;（2） the slantwise convection is not the only reason for banded cloud and precipitation, it needs integrated analysis with other instability mechanisms; （3）the wet symmetric instability and convective instability are coexistent.