Estimating random errors due to shot noise in backscatter lidar observations

Zhaoyan Liu; William Hunt; Mark Vaughan; Chris Hostetler; Matthew McGill; Kathleen Powell; David Winker; Yongxiang Hu

doi:10.1364/AO.45.004437

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Estimating random errors due to shot noise in backscatter lidar observations

Zhaoyan Liu, William Hunt, Mark Vaughan, Chris Hostetler, Matthew McGill, Kathleen Powell, David Winker and Yongxiang Hu

Applied optics (2004), Vol.45(18), pp.4437-4447

06/20/2006

DOI: 10.1364/AO.45.004437

PMID: 16778954

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Abstract

We discuss the estimation of random errors due to shot noise in backscatter lidar observations that use either photomultiplier tube (PMT) or avalanche photodiode (APD) detectors. The statistical characteristics of photodetection are reviewed, and photon count distributions of solar background signals and laser backscatter signals are examined using airborne lidar observations at 532 nm using a photon-counting mode APD. Both distributions appear to be Poisson, indicating that the arrival at the photodetector of photons for these signals is a Poisson stochastic process. For Poisson- distributed signals, a proportional, one-to-one relationship is known to exist between the mean of a distribution and its variance. Although the multiplied photocurrent no longer follows a strict Poisson distribution in analog-mode APD and PMT detectors, the proportionality still exists between the mean and the variance of the multiplied photocurrent. We make use of this relationship by introducing the noise scale factor (NSF), which quantifies the constant of proportionality that exists between the root mean square of the random noise in a measurement and the square root of the mean signal. Using the NSF to estimate random errors in lidar measurements due to shot noise provides a significant advantage over the conventional error estimation techniques, in that with the NSF, uncertainties can be reliably calculated from or for a single data sample. Methods for evaluating the NSF are presented. Algorithms to compute the NSF are developed for the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar and tested using data from the Lidar In-space Technology Experiment.

Details

Title: Subtitle: Estimating random errors due to shot noise in backscatter lidar observations
Creators: Zhaoyan Liu - National Institute of Aerospace
William Hunt - Langley Research Center
Mark Vaughan - Langley Research Center
Chris Hostetler - Langley Research Center
Matthew McGill - Goddard Space Flight Center
Kathleen Powell
David Winker - Langley Research Center
Yongxiang Hu - Langley Research Center
Resource Type: Journal article
Publication Details: Applied optics (2004), Vol.45(18), pp.4437-4447
DOI: 10.1364/AO.45.004437
PMID: 16778954
NLM abbreviation: Appl Opt
ISSN: 1559-128X
eISSN: 2155-3165
Language: English
Date published: 06/20/2006
Academic Unit: Physics and Astronomy; Chemical and Biochemical Engineering
Record Identifier: 9984276453502771

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