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Proceedings Paper

A maximum likelihood approach to determine sensor radiometric response coefficients for NPP VIIRS reflective solar bands
Author(s): Ning Lei; Kwo-Fu Chiang; Hassan Oudrari; Xiaoxiong Xiong
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Paper Abstract

Optical sensors aboard Earth orbiting satellites such as the next generation Visible/Infrared Imager Radiometer Suite (VIIRS) assume that the sensors' radiometric response in the Reflective Solar Bands (RSB) is described by a quadratic polynomial, in relating the aperture spectral radiance to the sensor Digital Number (DN) readout. For VIIRS Flight Unit 1 (FU1) (Butler, J., Xiong, X., Oudrari, H., Pan, C., and Gleason, J., "NASA Calibration and Characterization in the NPOESS Preparatory Project (NPP)", IGARSS, July 12-17, 2009, Cape Town, South Africa.), the coefficients are to be determined before launch by an attenuation method, although the linear coefficient will be further determined on-orbit through observing the Solar Diffuser. In determining the quadratic polynomial coefficients by the attenuation method, a Maximum Likelihood approach is applied in carrying out the least-squares procedure. Crucial to the Maximum Likelihood least-squares procedure is the computation of the weight. The weight not only has a contribution from the noise of the sensor's digital count, with an important contribution from digitization error, but also is affected heavily by the mathematical expression used to predict the value of the dependent variable, because both the independent and the dependent variables contain random noise. In addition, model errors have a major impact on the uncertainties of the coefficients. The Maximum Likelihood approach demonstrates the inadequacy of the quadratic model. We show that using the inadequate quadratic model dramatically increases the uncertainties of the coefficients. We compute the coefficient values and their uncertainties, considering both measurement and model errors.

Paper Details

Date Published: 13 September 2011
PDF: 11 pages
Proc. SPIE 8153, Earth Observing Systems XVI, 81530J (13 September 2011); doi: 10.1117/12.893933
Show Author Affiliations
Ning Lei, Sigma Space Corp. (United States)
Kwo-Fu Chiang, Sigma Space Corp. (United States)
Hassan Oudrari, Sigma Space Corp. (United States)
Xiaoxiong Xiong, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 8153:
Earth Observing Systems XVI
James J. Butler; Xiaoxiong Xiong; Xingfa Gu, Editor(s)

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