摘要
较强的热力不稳定和适宜的动力环境是强对流发展的基础 ,造成灾害的强对流一般是一种深厚对流 ,深对流指数和对流有效位能可反映对流上升运动的潜势和强度 ,对流有效位能还隐含地反映了对流层大气总体垂直热力结构。下沉对流有效位能和大风指数反映了对流下沉运动和下击暴流潜势 ,对流下沉和中层干空气的入侵高度、干燥程度及对流层中下层的稳定度和湿度有关。强风暴特别是超级单体一般都具有很高的螺旋性 ,高螺旋度有利于风暴生命的维持 ,而风暴相对螺旋度则对风暴发生及风暴类型有一定的预示。粗里查逊数反映了对流能量和环境场动力之间的平衡关系 ,能量螺旋度指数反映了动力和能量对强对流天气发展的共同效应 ,它们都综合了动力和热力两方面的因子 ,对强风暴及其类型的预报有指示意义。风暴强度指数和瑞士雷暴指数成功地把动力和对流能量参数结合起来 ,在实际研究和业务工作中这种方法值得借鉴。随着高分辨率中尺度和风暴模式的发展 ,模式输出的对流动力和能量参数将有广泛的应用前景。
The severe storm is caused by deep convection, and its development needs thermodynamic instability and a proper dynamic environment. Deep convective index and convective available potential energy present the potential of upward convection, while convective available potential energy reflects the whole thermodynamic structure in troposphere impliedly. Downdraft convective available potential energy and wind index present the downward convection and micro-downburst respectively. Downward convection is closely related with the altitude of the dry intrusive, the dryness of the air, the instability and the humidity of the low-level atmosphere. A proper vertical wind shear is favorable to severe storm. Severe storms, especially supercells, are always associated with high helicity which maintains a longer life cycle. The storm relative helicity is a predictive factor for severe storms. Bulk Richardson number reflects the balance between convective energy and dynamic effect. Energetic helicity index reflects the combination of the buoyancy energy and the dynamic effect. Both severe storm index and Swiss thunderstorm index are good examples for the use and the development of convective parameters. The combination of dynamic and energetic parameters is recommended in operational weather forecasting, and it is also recommend that multiple parameters should be used concurrently in order to reflect varied kinds of severe storms. Outlooks are made for the use of convective parameters in severe weather forecasting deduced by numerical model output.
出处
《气象学报》
CAS
CSCD
北大核心
2004年第4期401-409,共9页
Acta Meteorologica Sinica
基金
国家自然科学基金 (40 3750 1 6)
中国科学院科技奥运专项 (2 0 0 1BA90 4B0 9)
