摘要:
在非地转Q矢量的基础上,考虑天气系统发展的主要热力强迫因子——非绝热加热作用,引入非地转湿Q矢量的概念,并推导出其表达式以及用非地转湿Q矢量散度为唯一强迫项所表示的非地转ω方程.同时,用非地转湿Q矢量分析方法诊断了由北上台风倒槽引起的一次华北特大暴雨过程;结果表明,非地转湿Q矢量能较清楚地揭示暴雨过程系统的演变;通过比较非地转湿Q矢量、垂直速度和不考虑“湿”过程的“干”Q矢量散度与暴雨落区的配置关系,结果发现,非地转湿Q矢量与降水落区存在最佳的对应关系,非地转湿Q矢量散度负值区能较好地预报出未来6h的降水落区,而且其中心数值的大小与未来6h降水的强度存在正相关的对应关系,从而说明非地转湿Q矢量对于暴雨天气系统诊断和预报是一种十分有效的工具,其散度负值区可以作为未来6h降水落区预报的重要指标,为暴雨的预报提供了更广阔的思路.
Abstract:
Based on the non-geostrophic Q-vector,taking account of the main heating forcing factor-diabatic heating of the development of synoptic system,the concept of non-geostrophic wet Q-vector was proposed,an expression of the non-geostrophic wet Q vector and the whole non-geostrophic ω equation,in which the divergence of non-geostrophic wet Q-vector was taken as an only forcing term,was derived in this paper.At the same time,the non-geostrophic wet Q-vector was applied to diagnose a torrential rain process in North of China.The results suggested that the non-geostrophic wet Q-vector could clearly reveal the system development of the torrential rain; the corresponding relation between the divergence of the non-geostrophic wet Q-vector and the rain area was better than ω and the divergence of dry Q-vector; the negative area of the divergence of the non-geostrophic wet Q-vector could forecast the rain area of six hours in the future correctly,and its center value had positive correlation to the intensity of six hours precipitation in the future.It provided more valuable information for short range weather forecasting,the torrential rain especially.
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