Implementation of a 2D Wavelet Method to Probe Mixed Layer Height Using Lidar Observations

• Published in: International journal of environmental research and public health 2019-07, Vol.16 (14), p.2516
• Main Authors: Zhang, Ning, Yang, Fuyan, Chen, Yan
• Format: Article
• Language: English
• Subjects: Air pollution; China; Covariance; Decomposition; Image filters; Light; Methods; Outdoor air quality; Pollutants; Remote sensing; Reproducibility of Results; Standard deviation; Studies; Wavelet analysis; Wavelet transforms
• ISSN: 1660-4601; 1661-7827; 1660-4601
• DOI: 10.3390/ijerph16142516

A new method was developed to estimate mixed layer (ML) height with light detection and ranging (lidar) observations using a 2Dimensional (2D) wavelet method, which can consider the diurnal variation characteristics of ML height. Ideal signals and real lidar observations in Shanghai, China were used to evaluate the new method. The results showed that the new method is insensitive to the type of wavelet filters. The estimated ML heights obtained by the 2D wavelet method agreed well with both of the previous methods developed for the ML height probing using lidar, including the gradient method, the 1D-wavelet method, the standard deviation method, and the conventional radiosonde method. The primary differences among the results obtained via the different lidar methods occurred in the early morning or later afternoon; when the ML is well mixed, very small differences were observed among the different lidar methods. The new method showed better determination skills than other methods when compared to the radiosonde observation results. It also performed well when there were missing profiles or observation errors and it made the new method suitable for operations where data quality control may be missed.