ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
The Pattern Structure and Thermodynamic and Dynamic Processes of Severe Storms Associated with Linear Convective Gales
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Abstract:
In order to help weather forecasters understand the physical mechanisms concealed among observational phenomena and scientifically improve their warning skills, from the operational point of view on weather forecasting and warning, this paper emphatically discusses the scientific relationships between the mechanisms triggering linear convective gales and the structure evolution, thermodynamic and dynamic processes of convective storms and the cloud-water macrophysical processes, and also explains their “dominant characters” in the contemporary operational observation system. Besides, some scientific problems with different views or interpretations are discussed as well. The major results are as follows. The surface linear gales incurred by convective storms are directly derived from the internal vertical movement of storms, while major compositions of the vertical velocity are contributed by the cold pool forcing and the downward vertical gradient of the disturbed pressure for thermodynamic effect. The thermodynamic effect and cold pool effect are directly related to cloud-water macrophysical processes within storms, such as evaporation (condensation)， melting (sublimation), and their evolutions can be demonstrated by a series of observed phenomena, such as weak echo slot, descending rear inflow jet, MARC (mid-altitude radial convergence), mesocyclone, gust front and the acute variations of meteorological elements on surface. The pattern variations of linear convective storms are induced by the inner dynamic processes of storm systems or by the interaction between storm systems and ambient atmosphere. It can not be definitely considered that all linear convective storms should develop into squall lines with bow echoes. The RKW theory can essentially interpret the interaction between the integrated squall line and the vertical shear of ambient wind. Virtually, the ambient wind performs the principal function of leading the movement and propagation of squall line, and the development or maintenance of squall line is possibly controlled by its inner thermodynamic and dynamic processes.
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