The radiative transfer model (RT3), a vector radiative transfer (VRT) scheme in a plane-parallel atmosphere, was bounded by a rough ocean surface in this study. The boundary problem was solved using a Fourier series d...The radiative transfer model (RT3), a vector radiative transfer (VRT) scheme in a plane-parallel atmosphere, was bounded by a rough ocean surface in this study. The boundary problem was solved using a Fourier series decomposition of the radiation field as a function of the azimuth. For the case of a rough ocean surface, the decomposition was obtained by developing both the Fresnel reflection matrix and the probability distribution of the water facet orientation as Fourier series. The effect of shadowing by ocean surface waves was also considered in the boundary condition. The VRT model can compute the intensity and degree of polarization of the light at the top of the atmosphere (TOA), the ocean surface, and any level of the atmosphere in the ocean-atmosphere system. The results obtained by our model are in good agreement with those computed by Ahmad’s model. The simulated results showed that the shadow effects of wave facets on the intensity and the degree of polarization are negligible except at the ocean surface near the grazing angle, possibly because we did not consider the effect of white caps.展开更多
A new method of multi-coupled single scattering （MCSS） for solving a vector radiative transfer equation is de- veloped and made public on Internet. Recent solutions from Chandrasekhar＇s X-Y method is used to valida...A new method of multi-coupled single scattering （MCSS） for solving a vector radiative transfer equation is de- veloped and made public on Internet. Recent solutions from Chandrasekhar＇s X-Y method is used to validate the MCSS＇s result, which shows high precision. The MCSS method is theoretically simple and clear, so it can be easily and credibly extended to the simulation of aerosol/cloud atmosphere＇s radiative properties, which provides effective support for research into polarized remote sensing.展开更多
In recent years,polarization remote sensing has garnered increasing attention,particularly within the realm of meteorology.To accurately simulate polarization information,the vector discrete-ordinate radiative transfe...In recent years,polarization remote sensing has garnered increasing attention,particularly within the realm of meteorology.To accurately simulate polarization information,the vector discrete-ordinate radiative transfer(VDISORT)model developed earlier by the community is further enhanced to an advanced version(referred to as A-VDISORT)through an improved ocean surface reflection.The Fresnel reflection matrix,which includes wind-generated roughness and shading effects,is served by an ocean bidirectional reflection distribution function(BRDF).The simulation from AVDISORT is compared with SCIATRAN for a Rayleigh scattering atmosphere,and the influence of water-leaving radiance is analyzed by the PSTAR(Polarized System for Transfer of Atmospheric Radiation) model.For GaoFen-5 Directional Polarimetric Camera(DPC) observations with polarization and multi-angle information,clear-sky pixel recognition over the ocean is first carried out.The DPC reflectance of clear conditions is normalized and compared with the observations.It is shown that A-VDISORT has a high simulation accuracy with a bias of –0.0053.The difference between simulation and observation exhibits a standard normal probability distribution function.展开更多
The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scatteri...The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scattering phase matrix,such as the phase matrix derived from spherical particles or randomly oriented non-spherical particles.In this study,a new VDISORT is developed for general atmospheric scattering and boundary conditions.Stokes vector is decomposed into both sinusoidal and cosinusoidal harmonic modes,and the radiance at arbitrary viewing geometry is solved directly by adding two zero-weighted points in the Gaussian quadrature scheme.The complex eigenvalues in homogeneous solutions are also taken into full consideration.The accuracy of VDISORT model is comprehensively validated by four cases:Rayleigh scattering case,the spherical particle scattering case with the Legendre expansion coefficients of 0th-13th orders of the phase matrix(hereinafter L13),L13 with a polarized source,and the randomoriented oblate particle scattering case with the Legendre expansion coefficients of 0th-11th orders of the phase matrix(hereinafter L11).In all cases,the simulated radiances agree well with the benchmarks,with absolute biases less than 0.0065,0.0006,and 0.0008 for Rayleigh,unpolarized L13,and L11,respectively.Since a polarized bidirectional reflection distribution function(pBRDF)matrix is used as the lower boundary condition,VDISORT is now able to handle fully coupled atmospheric and surface polarimetric radiative transfer processes.展开更多
The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious ...The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious errors in the simulated radiances.In this study,the vector radiative transfer equation is solved with a polarized bidirectional reflection distribution function(pBRDF)for computing the surface-leaving radiation from the lower boundary.An azimuthally asymmetric pBRDF model at visible and infrared bands over oceans is fully coupled with the updated VDISORT model.The radiance at the ocean surface is combined with the contributions of atmospheric scattering and surface properties.It is shown that the radiance at the ocean surface also exhibits a strong angular dependence in the Stokes vector and the magnitudes of I.Q.and V increase for a larger azimuthal dependence of pBRDF.In addition,the solar position affects the peaks of sun glitter pattern,thus modulating the signal magnitudes and the angular distributions.As ocean wind increases,the reflection weakens with reduced magnitudes of Stokes parameters and lessvarying angular distributions.展开更多
Due to the polarization effects of the Earth’s surface reflection and atmospheric particles’scattering,high-precision retrieval of atmospheric parameters from near-infrared satellite data requires accurate vector at...Due to the polarization effects of the Earth’s surface reflection and atmospheric particles’scattering,high-precision retrieval of atmospheric parameters from near-infrared satellite data requires accurate vector atmospheric radiative transfer simulations.This paper presents a near-infrared vector radiative transfer model based on the doubling and adding method.This new model utilizes approximate calculations of the atmospheric transmittance,reflection,and solar scattering radiance for a finitely thin atmospheric layer.To verify its accuracy,the results for four typical scenarios(single molecular layer with Rayleigh scattering,single aerosol layer scattering,multi-layer Rayleigh scattering,and true atmospheric with multi-layer molecular absorption,Rayleigh and aerosol scattering)were compared with benchmarks from a well-known model.The comparison revealed an excellent agreement between the results and the reference data,with accuracy within a few thousandths.Besides,to fulfill the retrieval algorithm,a numerical differentiation-based Jacobian calculation method is developed for the atmospheric and surface parameters.This is coupled with the adding and doubling process for the radiative transfer calculation.The Jacobian matrix produced by the new algorithm is evaluated by comparison with that from the perturbation method.The relative Jacobian matrix deviations between the two methods are within a few thousandths for carbon dioxide and less than 1.0×10-3%for aerosol optical depth.The two methods are consistent for surface albedo,with a deviation below 2.03×10-4%.All validation results suggest that the accuracy of the proposed radiative transfer model is suitable for inversion applications.This model exhibits the potential for simulating near-infrared measurements of greenhouse gas monitoring instruments.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-QN201)the National Natural Science Foundation of China (Grant No. 40805010)+2 种基金the National Basic Research Program of China (973 Program, Grant No. 2010CB 950804)Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (Grant No. 2008BAC40B01)supported by a Post-doctoral Fellowship for Space Science and Application
文摘The radiative transfer model (RT3), a vector radiative transfer (VRT) scheme in a plane-parallel atmosphere, was bounded by a rough ocean surface in this study. The boundary problem was solved using a Fourier series decomposition of the radiation field as a function of the azimuth. For the case of a rough ocean surface, the decomposition was obtained by developing both the Fresnel reflection matrix and the probability distribution of the water facet orientation as Fourier series. The effect of shadowing by ocean surface waves was also considered in the boundary condition. The VRT model can compute the intensity and degree of polarization of the light at the top of the atmosphere (TOA), the ocean surface, and any level of the atmosphere in the ocean-atmosphere system. The results obtained by our model are in good agreement with those computed by Ahmad’s model. The simulated results showed that the shadow effects of wave facets on the intensity and the degree of polarization are negligible except at the ocean surface near the grazing angle, possibly because we did not consider the effect of white caps.
基金Project supported by the Science Foundation of the Airborne Remote Sensing System,Large Research Infrastructure of the Chinese Academy of Sciences
文摘A new method of multi-coupled single scattering （MCSS） for solving a vector radiative transfer equation is de- veloped and made public on Internet. Recent solutions from Chandrasekhar＇s X-Y method is used to validate the MCSS＇s result, which shows high precision. The MCSS method is theoretically simple and clear, so it can be easily and credibly extended to the simulation of aerosol/cloud atmosphere＇s radiative properties, which provides effective support for research into polarized remote sensing.
基金supported by the National Natural Science Foundation of China(Grant No.U2142212)National Key R&D Program of China(Grant No.2019QZKK,Qinghai Tibet KeKao)the National Natural Science Foundation of China(Grant No.U2242211)。
文摘In recent years,polarization remote sensing has garnered increasing attention,particularly within the realm of meteorology.To accurately simulate polarization information,the vector discrete-ordinate radiative transfer(VDISORT)model developed earlier by the community is further enhanced to an advanced version(referred to as A-VDISORT)through an improved ocean surface reflection.The Fresnel reflection matrix,which includes wind-generated roughness and shading effects,is served by an ocean bidirectional reflection distribution function(BRDF).The simulation from AVDISORT is compared with SCIATRAN for a Rayleigh scattering atmosphere,and the influence of water-leaving radiance is analyzed by the PSTAR(Polarized System for Transfer of Atmospheric Radiation) model.For GaoFen-5 Directional Polarimetric Camera(DPC) observations with polarization and multi-angle information,clear-sky pixel recognition over the ocean is first carried out.The DPC reflectance of clear conditions is normalized and compared with the observations.It is shown that A-VDISORT has a high simulation accuracy with a bias of –0.0053.The difference between simulation and observation exhibits a standard normal probability distribution function.
基金Supported by the Natural Science Program of China(U2142212)Natural Science Foundation of Hunan Province(2021JC0009)National Key Research and Development Program of China(2022YFC3004200)。
文摘The original vector discrete ordinate radiative transfer(VDISORT)model takes into account Stokes radiance vector but derives its solution assuming azimuthal symmetric surface reflective matrix and atmospheric scattering phase matrix,such as the phase matrix derived from spherical particles or randomly oriented non-spherical particles.In this study,a new VDISORT is developed for general atmospheric scattering and boundary conditions.Stokes vector is decomposed into both sinusoidal and cosinusoidal harmonic modes,and the radiance at arbitrary viewing geometry is solved directly by adding two zero-weighted points in the Gaussian quadrature scheme.The complex eigenvalues in homogeneous solutions are also taken into full consideration.The accuracy of VDISORT model is comprehensively validated by four cases:Rayleigh scattering case,the spherical particle scattering case with the Legendre expansion coefficients of 0th-13th orders of the phase matrix(hereinafter L13),L13 with a polarized source,and the randomoriented oblate particle scattering case with the Legendre expansion coefficients of 0th-11th orders of the phase matrix(hereinafter L11).In all cases,the simulated radiances agree well with the benchmarks,with absolute biases less than 0.0065,0.0006,and 0.0008 for Rayleigh,unpolarized L13,and L11,respectively.Since a polarized bidirectional reflection distribution function(pBRDF)matrix is used as the lower boundary condition,VDISORT is now able to handle fully coupled atmospheric and surface polarimetric radiative transfer processes.
基金Supported by the National Natural Science Foundation of China(U2142212 and U2242211),Hunan Provincial Natural Science Foundation of China(2021JC0009)National Key Research and Development Program of China[2019QZKK(Qinghai Tibet KeKao)].
文摘The reflection of ocean surface is often assumed azimuthally symmetric in the previous vector discrete ordinate radiative transfer(VDISORT)and many other radiative transfer solvers.This assumption can lead to obvious errors in the simulated radiances.In this study,the vector radiative transfer equation is solved with a polarized bidirectional reflection distribution function(pBRDF)for computing the surface-leaving radiation from the lower boundary.An azimuthally asymmetric pBRDF model at visible and infrared bands over oceans is fully coupled with the updated VDISORT model.The radiance at the ocean surface is combined with the contributions of atmospheric scattering and surface properties.It is shown that the radiance at the ocean surface also exhibits a strong angular dependence in the Stokes vector and the magnitudes of I.Q.and V increase for a larger azimuthal dependence of pBRDF.In addition,the solar position affects the peaks of sun glitter pattern,thus modulating the signal magnitudes and the angular distributions.As ocean wind increases,the reflection weakens with reduced magnitudes of Stokes parameters and lessvarying angular distributions.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFB0504900&2018YFB0504905)the National Natural Science Foundation of China(Grant No.41975034)the Special Fund for Scientific Research(Meteorology)in the Public Interest(Grant Nos.GYHY201506022&GYHY201506002)。
文摘Due to the polarization effects of the Earth’s surface reflection and atmospheric particles’scattering,high-precision retrieval of atmospheric parameters from near-infrared satellite data requires accurate vector atmospheric radiative transfer simulations.This paper presents a near-infrared vector radiative transfer model based on the doubling and adding method.This new model utilizes approximate calculations of the atmospheric transmittance,reflection,and solar scattering radiance for a finitely thin atmospheric layer.To verify its accuracy,the results for four typical scenarios(single molecular layer with Rayleigh scattering,single aerosol layer scattering,multi-layer Rayleigh scattering,and true atmospheric with multi-layer molecular absorption,Rayleigh and aerosol scattering)were compared with benchmarks from a well-known model.The comparison revealed an excellent agreement between the results and the reference data,with accuracy within a few thousandths.Besides,to fulfill the retrieval algorithm,a numerical differentiation-based Jacobian calculation method is developed for the atmospheric and surface parameters.This is coupled with the adding and doubling process for the radiative transfer calculation.The Jacobian matrix produced by the new algorithm is evaluated by comparison with that from the perturbation method.The relative Jacobian matrix deviations between the two methods are within a few thousandths for carbon dioxide and less than 1.0×10-3%for aerosol optical depth.The two methods are consistent for surface albedo,with a deviation below 2.03×10-4%.All validation results suggest that the accuracy of the proposed radiative transfer model is suitable for inversion applications.This model exhibits the potential for simulating near-infrared measurements of greenhouse gas monitoring instruments.
