ANALYSIS OF MULTI-SCALE ENERGY INTERACTION ON THE UPSCALE GROWTH OF A SQUALL LINE IN SOUTH CHINA
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摘要: 采用WRF模式对华南飑线的升尺度增长过程进行模拟,利用Barnes滤波将模式数据分解为三个尺度,分别代入相应的能量方程中进行计算,从能量角度研究飑线升尺度增长过程中动能和位能的变化,以及三个尺度系统能量的相互转化。研究表明:动能的变化与飑线过程中各尺度系统的演变有较好的对应,β中小尺度对流的发展对应β中小尺度系统动能的变化,而在飑线升尺度增长过程中,α中尺度系统动能快速增长。在飑线发展过程中环境场通过位能向动能的转化使得β中小尺度对流快速发展加强,而β中尺度飑线的快速发展与合并加强导致了飑线的升尺度增长。在飑线的升尺度增长过程中,β中小尺度动能大量转化为α中尺度动能使得α中尺度飑线迅速增强,而环境场对飑线升尺度增长过程的直接影响较小。Abstract: In the present study, the upscale growth of a squall line in south China is simulated by using the Weather Research and Forecasting Model and the change and the mutual conversion of energy during the upscale growth is analyzed. Barnes filter is used to decompose the model data into three scales, which are substituted into corresponding energy equation for calculation. The research shows that in this process, the change of kinetic energy corresponds to the evolution of the system at all scales during the squall line process; the development of β mesoscale convective systems corresponds to the change of kinetic energy of β mesoscale systems, and during the upscale growth of the squall line, the kinetic energy of α mesoscale system increases rapidly. During the development of the squall line, environmental field facilitates the development of β mesoscale convection as potential energy has been converted to kinetic energy, and the rapid development and merge of the β mesoscale squall line results in the upscale growth of the squall line. In the upscale growth of the squall line, β mesoscale kinetic energy is converted into α mesoscale kinetic energy, which leads to the rapid development of α mesoscale squall line, and the environmental field has little direct influence on the upscale growth of this squall line.
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Key words:
- squall line /
- upscale growth /
- multi-scale /
- energy /
- interaction
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图 6 同图 5,但为三个尺度之间动能的转化
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