中上层冷平流对飑线发生的影响

飑线的产生经常与不稳定能量和垂直风切变相联系。本文提出了对流层中上层温度平流的一种诊断方法。应用这一方法分析了一些例子中700—300 hPa间的平流值。结果表明，冷平流会引起不稳定能量E的增加，E和的大小对强飑线的发生有一定指示作用。文中指出垂直风切变及其变化与温度平流的存在是紧密相关的。还指出分析不稳定能量和中上层温度平流的水平分布对预报飑线发生的区域是有用的。

Influence of Cold Advection in Mid–and–upper Troposphere on Squall Line Occurrence

The occurrence of squall lines is frequently associated with instability energy and vertical wind shear. In this paper, a method for diagnosing temperature advection in mid-and-upper troposphere is proposed, with which the advection magnitudes between 700 and 300 hPa in several cases are analysed. Results show that the cold advection would cause an increase in the instability energy E between 700 hPa and 300 hPa and the magnitudes of E and could present a certain indication for the formation of strong squall lines. It is pointed out that vertical wind shear and its change are closely correlated with the temperature advection. It is also emphasized that analysis of horizontal distribution of instability energy and cold advection is useful for forecasting the area in which squall lines occur.