为了研究测量混合层高度的方法,对判断混合层高度的几种重要方法,如目测法、梯度法等进行了分析,采用本文中所介绍的的Steyn法,通过阐述其理论基础,给出了理想模型图,并举例强调实际运用时初始值选择对拟合结果的影响。利用云高仪Vaisala测得的3幅雷达回波信号图(气溶胶后向散射系数和高度)进行拟合,得到了混合层高度等结果。结果表明,Steyn法即使在混合层后向散射系数多变、混合层高度偏低的复杂情况下,仍能准确有效地识别混合层高度、夹卷层厚度等信息,大气边界层日变化的实测结果与理论预测值能较好地吻合。

In order to study the methods of determining the height of the mixing layer,some important methods,such as visual inspection and gradient method,were analyzed.A novel method,namely the Steyn method,was put forward.After describing its basic principle,its ideal model was given out.It was emphasized how the initial value affected the fit result.Then the signals (the profile of aerosol backscatter coefficient and height) obtained from the ceilomter Vaisala CL31 were fitted and the height of the mixing layer was obtained.The results show that with the Steyn method,some information,such as the mixing layer height and the entrainment depth,can be obtained accurately no matter the backscatter vertical distribution varies greatly or the mixing layer is very shallow.The spatial and time distribution of the mixing layer height agrees with the theoretical prediction very well.