气候变化领域集成服务门户(CCPortal): Optimal estimation method applied on ceilometer aerosol retrievals

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DOI	10.1016/j.atmosenv.2021.118243
	Optimal estimation method applied on ceilometer aerosol retrievals
	Bedoya-Velásquez A.E.; Ceolato R.; Lefebvre S.
发表日期	2021
ISSN	1352-2310
卷号	249
英文摘要	The solution of the lidar equation is an ill-posed problem that requires nonlinear methods to retrieve the atmospheric aerosol optical and microphysical properties. Particularly, in the last decades, the most applied solution for the elastic lidars is through the well known Klett-Fernald-Sasano algorithm for retrieving the backscatter coefficient. To solve this inversion problem, we propose to apply the optimal estimation method to a Vaisala CL51 ceilometer range corrected signals for retrieving under two different frameworks, the particle backscatter coefficient or the ratio and the lidar constant. The optimal estimation is a Bayesian inversion fed by a set of a priori information. In this work, to obtain the suitable prior, we have tested two approaches that involved measurements and synthetic data. The first data set was obtained from previous inversions using the classical Klett-Fernald-Sasano method, and the second one by using Mie simulations fed by aerosol properties from OPAC database. The optimal estimation method used for elastic lidar inversion presents two main advantages compared to the classic approaches. On one hand, there is no need for Rayleigh zone determination and on the other hand, the uncertainty of the retrieved products is directly estimated, therefore the quality of the results is highly dependant on the prior selection. To evaluate the performance of the model, low and high aerosol accumulations scenarios were considered, finding that the backscatter coefficient was oscillating between 5 and 7 (kmsr)−1 in the first 3 km agl with uncertainties lower than 27 %at degraded spatial resolutions. Additionally, constant and height-dependent priors were tested reaching relative errors in percentage up to 5% between them. Besides, relative errors were also analyzed for the prior covariance matrices estimated either from synthetic lidar data and Klett's retrievals, where the errors are lower than 2% by using one instead of the another. However, scale factors were applied to the synthetic prior covariance matrices to reach the convergence. The results at retrieving the particle backscattering were compared to those ones estimated from Klett's inversion, considering Klett inversion as the reference. For the extreme scenario of inversions, considering aerosol accumulations at different layers, the bias between the optimized profiles was lower than −0.5 (kmsr)−1 in the first 0.5 km and 0.5 (kmsr)−1 above 1.5 km. Here, we also shown a two-parameter optimization for the lidar constant and lidar ratio, applied to 39 aerosol inversions, finding relative errors lower than 1 % and 2.3 %, respectively, considering those ones from Klett inversion as the reference. © 2021 Elsevier Ltd
关键词	Ceilometer vaisala CL51 Nonlinear elastic aerosol inversion Optimal estimation method
语种	英语
scopus关键词	Atmospheric aerosols; Backscattering; Covariance matrix; Errors; Meteorological instruments; Nonlinear equations; Uncertainty analysis; Aerosol properties; Backscatter coefficients; Bayesian inversion; Covariance matrices; Microphysical property; Optimal estimation methods; Optimal estimations; Spatial resolution; Optical radar; aerosol; algorithm; data set; database; estimation method; lidar; numerical model; optimization; performance assessment; uncertainty analysis; aerosol; article; covariance; information retrieval; simulation; uncertainty
来源期刊	ATMOSPHERIC ENVIRONMENT
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/248548
作者单位	ONERA/DOTA, Universite de Toulouse, Toulouse, 31055, France
推荐引用方式 GB/T 7714	Bedoya-Velásquez A.E.,Ceolato R.,Lefebvre S.. Optimal estimation method applied on ceilometer aerosol retrievals[J],2021,249.
APA	Bedoya-Velásquez A.E.,Ceolato R.,&Lefebvre S..(2021).Optimal estimation method applied on ceilometer aerosol retrievals.ATMOSPHERIC ENVIRONMENT,249.
MLA	Bedoya-Velásquez A.E.,et al."Optimal estimation method applied on ceilometer aerosol retrievals".ATMOSPHERIC ENVIRONMENT 249(2021).