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Keywords = SHDOM

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22 pages, 751 KB  
Article
A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere
by Adrian Doicu, Dmitry S. Efremenko and Thomas Trautmann
Remote Sens. 2021, 13(2), 270; https://doi.org/10.3390/rs13020270 - 14 Jan 2021
Viewed by 2348
Abstract
An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization [...] Read more.
An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate. Full article
(This article belongs to the Special Issue Current Advances in Radiative Transfer Modeling for Satellite Optical Remote Sensing Applications)
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17 pages, 747 KB  
Article
A Spectral Acceleration Approach for the Spherical Harmonics Discrete Ordinate Method
by Adrian Doicu, Dmitry S. Efremenko and Thomas Trautmann
Remote Sens. 2020, 12(22), 3703; https://doi.org/10.3390/rs12223703 - 11 Nov 2020
Cited by 5 | Viewed by 4016
Abstract
A spectral acceleration approach for the spherical harmonics discrete ordinate method (SHDOM) is designed. This approach combines the correlated k-distribution method and some dimensionality reduction techniques applied on the optical parameters of an atmospheric system. The dimensionality reduction techniques used in this [...] Read more.
A spectral acceleration approach for the spherical harmonics discrete ordinate method (SHDOM) is designed. This approach combines the correlated k-distribution method and some dimensionality reduction techniques applied on the optical parameters of an atmospheric system. The dimensionality reduction techniques used in this study are the linear embedding methods: principal component analysis, locality pursuit embedding, locality preserving projection, and locally embedded analysis. Through a numerical analysis, it is shown that relative to the correlated k-distribution method, PCA in conjunction with a second-order of scattering approximation yields an acceleration factor of 12. This implies that SHDOM equipped with this acceleration approach is efficient enough to perform spectral integration of radiance fields in inhomogeneous multi-dimensional media. Full article
(This article belongs to the Special Issue Current Advances in Radiative Transfer Modeling for Satellite Optical Remote Sensing Applications)
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23 pages, 5130 KB  
Article
A Numerical Study of Effects of Radiation on Deep Convective Warm Based Cumulus Cloud Development with a 3-D Radiative Transfer Model
by Tianyu Zhang, Jiming Sun and Yi Yang
Atmosphere 2020, 11(11), 1187; https://doi.org/10.3390/atmos11111187 - 2 Nov 2020
Cited by 5 | Viewed by 3407
Abstract
The effects of radiation heating and cooling on cumulus cloud development have been the focus of considerable attention for many years. However, it is still not clear how radiation impacts cloud droplet growth. Since cloud inhomogeneity has a great influence on radiation transmission, [...] Read more.
The effects of radiation heating and cooling on cumulus cloud development have been the focus of considerable attention for many years. However, it is still not clear how radiation impacts cloud droplet growth. Since cloud inhomogeneity has a great influence on radiation transmission, we coupled the 3D atmospheric radiative transfer model using the spherical harmonic discrete ordinate method with WRF-LES, which can improve the simulation accuracy of the inhomogeneous effect of clouds on radiation compared with that of the 1D radiation method. The shortwave and longwave radiation fluxes for upward and downward directions were simulated with different solar zenith angles. The comparison of 1D and 3D radiative solvers for deep convective cloud cases shows that the 3D radiative solver provides an accurate structure of solar and thermal radiation characteristics and the spatial distribution field. The solar radiation heating is likely to increase perpendicular to the solar incidence direction. For longwave radiation, the cooling effect on the cloud top and the heating effect on the cloud base are both more intense in the 3D radiation model. This study focuses on 3D cloud-radiative interactions in an inhomogeneous cloud field in a large eddy simulation, and the results suggest that compared with the widely used 1D radiative solver in WRF, the 3D radiation model can provide a precise description of the radiation field in an inhomogeneous atmosphere. Full article
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30 pages, 710 KB  
Article
Linearizations of the Spherical Harmonic Discrete Ordinate Method (SHDOM)
by Adrian Doicu and Dmitry S. Efremenko
Atmosphere 2019, 10(6), 292; https://doi.org/10.3390/atmos10060292 - 28 May 2019
Cited by 10 | Viewed by 4665
Abstract
Linearizations of the spherical harmonic discrete ordinate method (SHDOM) by means of a forward and a forward-adjoint approach are presented. Essentially, SHDOM is specialized for derivative calculations and radiative transfer problems involving the delta-M approximation, the TMS correction, and the adaptive grid splitting, [...] Read more.
Linearizations of the spherical harmonic discrete ordinate method (SHDOM) by means of a forward and a forward-adjoint approach are presented. Essentially, SHDOM is specialized for derivative calculations and radiative transfer problems involving the delta-M approximation, the TMS correction, and the adaptive grid splitting, while practical formulas for computing the derivatives in the spherical harmonics space are derived. The accuracies and efficiencies of the proposed methods are analyzed for several test problems. Full article
(This article belongs to the Special Issue Radiative Transfer Models of Atmospheric and Cloud Properties)
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