Software for retrieval of aerosol particle size distribution from multiwavelength lidar signals

Abstract

Software to retrieve profiles of aerosol particle size distribution (APSD) from multiwavelength lidar signals is presented. The approach consists in direct fit of artificial signal generated using predefined distribution to the experimental signals. Combination of two lognormal functions with a few free parameters is applied for the predefined APSD. The minimization technique allows finding lognormal function parameters which provide the best fit. The approach was tested on the experimental signals registered at 1064, 532 and 355 nm. The software is designated for processing on PCs. The computation time was about several minutes. Program summaryProgram title: APSD_SoftwareCatalogue identifier: AEXV_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEXV_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Open LicenceNo. of lines in distributed program, including test data, etc.: 12813No. of bytes in distributed program, including test data, etc.: 878099Distribution format: tar.gzProgramming language: Delphi 2010.Computer: PC.Operating system: Windows XP, Vista, 7, 8, 8.1.RAM: 37MBClassification: 13.Nature of problem:Aerosol Particle Size Distribution (APSD) is a very significant function for evaluation of atmospheric optical properties. Remote determination of APSD might be performed with multiwavelength lidar. Retrieval of profiles of APSD from multiwavelength lidar signals is an example of ill-posed problem in the atmospheric physics (in the sense of Jacques Hadamard).Solution method:The approach consists in direct fit of artificial signals to the experimental signals. The artificial signals are generated using predefined aerosol particle distribution, Combination of two lognormal functions with a few free parameters is applied for the predefined APSD. The minimization technique used in the software allows finding lognormal function parameters which provide the best fit.Additional comments:The input signal should be located into the SIGNALS directory which is automatically created by the software. The results are presented in the main form of the software. They are also saved into the same directory from which it was loaded input file. They are saved as a BitMap as well as the ASCII files. The software returns two main sets of files: first one “APSD.bmp” and “APSD_Iet.txt”, and the second one “EffectiveRadius.bmp” and “EffectiveRadius.txt”.Running time:195 s for an input file consisting 12 measurement points (altitudes).