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Proceedings Paper

Retrieval of microphysical parameters from return signals of airborne and space-based lidars
Author(s): Ulrich G. Oppel; Heike Krasting
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Paper Abstract

We show some examples of real and simulated return signals of airborne and space-based LIDARs. These return signals from cirrus and water clouds demonstrate the contributions from the different orders of multiple scattering. For a space-based LIDAR even for subvisible cirrus clouds the contribution from multiple scattering is substantial, for water clouds it is absolutely dominant. For an airborne LIDAR multiple scattering is much less important. The simulations have been done using variance reduction Monte Carlo methods allowing for controlling the variance. The variance reduction methods of these Monte Carlo methods are based on scattering splitting, extinction splitting, exponential transform, and local estimates. Our program for the calculation of multiply scattered LIDAR returns has been tested successfully in several international contests. It reproduces real LIDAR returns obtained from the space-based LITE (NASA) and from the airborne ALEX (DLR) equally well. We propose a very efficient and a very generally applicable procedure for the retrieval of microphysical parameters from such multiply scattered LIDAR returns. This procedure is based on the combination of a comparison of the measured signal with simulated signals and a uniform grid or random search procedure for minimization. As a by-product this retrieval technique allows for a sensitivity analysis of the dependence of the signals on variations of parameters. We apply the retrieval method to obtain the variable extinction coefficient of a cirrus cloud from the real LIDAR returns of the airborne lidar ALEX and the space- based lidar LITE.

Paper Details

Date Published: 26 May 1997
PDF: 10 pages
Proc. SPIE 3104, Lidar Atmospheric Monitoring, (26 May 1997); doi: 10.1117/12.275141
Show Author Affiliations
Ulrich G. Oppel, Ludwig-Maximilians-Univ. Muenchen (Germany)
Heike Krasting, Ludwig-Maximilians-Univ. Muenchen (Germany)

Published in SPIE Proceedings Vol. 3104:
Lidar Atmospheric Monitoring
Jean-Pierre Wolf, Editor(s)

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