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Proceedings Paper

Methods of assessing uncertainty in determining particle size distribution parameters from optical backscatter and extinction measurements
Author(s): Ben R. Herman; Barry Gross; Fred Moshary; Samir Ahmed
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Paper Abstract

The use of multi-wavelength lidar measurements can in principle be used to estimate aerosol extinction and backscatter profiles. From the resultant multi-wavelength profiles, an estimate of particle size distribution parameters can be inferred. However, the confidence of the retrieval depends on the accuracy of the retrieved backscatter and extinction coefficients. Conventional approaches determine errors by performing statistical calculations on the results of inversions of simulated measurements with errors derived from a random number generator. There is a certain ambiguity about the validity of this method which we try to resolve. We introduce two alternative methods. One is a reverse Monte-Carlo method which gives an ensemble of distribution parameters that produce simulated measurements whose inversions match the inversion of the retrieved measurements. Substantial differences in the results of the aforementioned methods were found. In order to clarify these differences, a semi-analytic approach is introduced that formulates the conditional probability density function of underlying particle size distribution parameters given a set of measurements (from the combined probability function with the underlying optical data). Results using the probability density function were found to be closer to the statistics of the reverse Monte-Carlo method than the conventional method.

Paper Details

Date Published: 23 December 2003
PDF: 8 pages
Proc. SPIE 5154, Lidar Remote Sensing for Environmental Monitoring IV, (23 December 2003); doi: 10.1117/12.509348
Show Author Affiliations
Ben R. Herman, CUNY/City College (United States)
Barry Gross, CUNY/City College (United States)
Fred Moshary, CUNY/City College (United States)
Samir Ahmed, CUNY/City College (United States)

Published in SPIE Proceedings Vol. 5154:
Lidar Remote Sensing for Environmental Monitoring IV
Upendra N. Singh, Editor(s)

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