激光雷达探测大气边界层高度的方法研究

Research on the method of detecting atmospheric boundary layer height using lidar

大气边界层高度的演变对污染物的扩散和空气质量的预测起着重要的作用.针对不同天气条件下边界层高度的识别问题,本研究选取合肥地区两种不同天气状况(轻雾霾天和晴天)下的大气层作为研究对象.首先,对经过噪声去除和距离平方校正后的回波信号,利用标准偏差法反演得到初步的边界层高度;接着,对反演的边界层高度结果进行筛选,并将筛选后的数据进行变分模态分解,得到重构后的边界层高度变化廓线;最后,综合考虑边界层演变发展的日变化特征,分析了不同反演方法下边界层高度逐小时平均变化情况及其随地面温度的变化.结果表明:直接利用标准偏差法与梯度法反演的边界层高度在某些时间段上具有较大的偏差,而使用变分模态分解方法得到的边界层高度结果则相对稳定且误差较小,说明该处理方法具有一定的优势;同时,边界层高度与地面温度的变化趋势一致,也表明边界层高度的识别结果是可靠的.

The evolution of atmospheric boundary layer height plays an important role in the diffusion of pollutants and the prediction of air quality.In this article,in order to detect the height of the boundary layer under different weather conditions,the atmosphere of the Hefei region is studied under two different weather conditions(light haze day and clear day).Firstly,the initial boundary layer height is determined using the standard deviation method by inverting the echo signal after removing noise and correcting for distance squared;the inverted boundary layer height results are then filtered,and the filtered data are subjected to variational mode decomposition to obtain the reconstructed boundary layer height information.Finally,taking into account the daily variation characteristics of the evolution and development of the boundary layer,the hourly average variation of boundary layer height and its variation with ground temperature under different inversion methods are analyzed.The results show that the boundary layer height obtained by the variational mode decomposition method is more stable and accurate than the standard deviation and gradient methods,which show significant deviations at certain times,indicating that the variational mode decomposition method has certain benefits.At the same time,the trend of boundary layer height and surface temperature is consistent,indicating the reliability of the identified boundary layer height.