Spectrally Invariant Approximation within Atmospheric Radiative TransferSource: Journal of the Atmospheric Sciences:;2011:;Volume( 068 ):;issue: 012::page 3094DOI: 10.1175/JAS-D-11-060.1Publisher: American Meteorological Society
Abstract: ertain algebraic combinations of single scattering albedo and solar radiation reflected from, or transmitted through, vegetation canopies do not vary with wavelength. These ?spectrally invariant relationships? are the consequence of wavelength independence of the extinction coefficient and scattering phase function in vegetation. In general, this wavelength independence does not hold in the atmosphere, but in cloud-dominated atmospheres the total extinction and total scattering phase function vary only weakly with wavelength. This paper identifies the atmospheric conditions under which the spectrally invariant approximation can accurately describe the extinction and scattering properties of cloudy atmospheres. The validity of the assumptions and the accuracy of the approximation are tested with 1D radiative transfer calculations using publicly available radiative transfer models: Discrete Ordinate Radiative Transfer (DISORT) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). It is shown for cloudy atmospheres with cloud optical depth above 3, and for spectral intervals that exclude strong water vapor absorption, that the spectrally invariant relationships found in vegetation canopy radiative transfer are valid to better than 5%. The physics behind this phenomenon, its mathematical basis, and possible applications to remote sensing and climate are discussed.
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contributor author | Marshak, A. | |
contributor author | Knyazikhin, Y. | |
contributor author | Chiu, J. C. | |
contributor author | Wiscombe, W. J. | |
date accessioned | 2017-06-09T16:55:02Z | |
date available | 2017-06-09T16:55:02Z | |
date copyright | 2011/12/01 | |
date issued | 2011 | |
identifier issn | 0022-4928 | |
identifier other | ams-76460.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4218909 | |
description abstract | ertain algebraic combinations of single scattering albedo and solar radiation reflected from, or transmitted through, vegetation canopies do not vary with wavelength. These ?spectrally invariant relationships? are the consequence of wavelength independence of the extinction coefficient and scattering phase function in vegetation. In general, this wavelength independence does not hold in the atmosphere, but in cloud-dominated atmospheres the total extinction and total scattering phase function vary only weakly with wavelength. This paper identifies the atmospheric conditions under which the spectrally invariant approximation can accurately describe the extinction and scattering properties of cloudy atmospheres. The validity of the assumptions and the accuracy of the approximation are tested with 1D radiative transfer calculations using publicly available radiative transfer models: Discrete Ordinate Radiative Transfer (DISORT) and Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART). It is shown for cloudy atmospheres with cloud optical depth above 3, and for spectral intervals that exclude strong water vapor absorption, that the spectrally invariant relationships found in vegetation canopy radiative transfer are valid to better than 5%. The physics behind this phenomenon, its mathematical basis, and possible applications to remote sensing and climate are discussed. | |
publisher | American Meteorological Society | |
title | Spectrally Invariant Approximation within Atmospheric Radiative Transfer | |
type | Journal Paper | |
journal volume | 68 | |
journal issue | 12 | |
journal title | Journal of the Atmospheric Sciences | |
identifier doi | 10.1175/JAS-D-11-060.1 | |
journal fristpage | 3094 | |
journal lastpage | 3111 | |
tree | Journal of the Atmospheric Sciences:;2011:;Volume( 068 ):;issue: 012 | |
contenttype | Fulltext |