In China's first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lun...In China's first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness,and global evaluation of 3He content.To analyze the modeling of microwave radiative transfer from three-layered media of lunar surface,some factors,such as the cratered lunar surface roughness,scattering of regolith particulate medium with temperature profile,are discussed.Based on the statistics of the lunar cratered terrain and using Monte Carlo (MC) method,the cratered lunar surfaces are numerically generated.The triangulated network is utilized to divide the undulated lunar surface into discrete triangle meshes with the size 10 m as a digital surface topography.The reflectivities of each plane mesh are calculated,and the average reflectivity for all MC-realized lunar surfaces is obtained.It is found that under the spatial resolution of 30 km×30 km of Chang-E 1 radiometer observation,the lunar surface can be well modeled as a flat surface.It makes the predominance of the parameters,such as the regolith layer thickness and stratified structures,to be studied.Using the radiative transfer equation of stratified media with dense scatterers,the scattering coefficient of the regolith particulate medium is found negligible,and the emission is mainly governed by the absorptive property of the medium.Brightness temperature of multi-layered media,i.e.lunar soil,regolith layer with temperature profile and underlying rock media,are derived and calculated,and relevant main factors to affect the modeling and emission simulation are analyzed.展开更多
A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common ran...A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common randomly rough surfaces without obvious two-scale characteristics, a scale-compression filter can divide the auto-correlation spectrum into two parts with different correlation lengths. The Kirchhoff approximation and the small perturbation method are used to obtain the surface field, then a bistatic scattering model, the bi-spectrum model (BSM), is used to derive an explicit expression from the surface field. Examples using the integral equation model (IEM), finite difference of the time domain (FDTD) method, and BSM show that the BSM accuracy is acceptable and its range of validity is similar to IEM. BSM can also be extended to a scattering model for dielectric randomly rough surfaces.展开更多
The bistatic scattering model is offen used for remote microwave sensing. The bi-spectrum model (BSM) for conducting surfaces was used to develop a scattering model for dielectric randomly rough surfaces to estimate ...The bistatic scattering model is offen used for remote microwave sensing. The bi-spectrum model (BSM) for conducting surfaces was used to develop a scattering model for dielectric randomly rough surfaces to estimate their bistatic scattering coefficients. The model for dielectric rough surfaces differs from the BSM for a conducting surface by including Fresnell reflection and transmission from dielectric rough surfaces. The bistatic scattering coefficients were defined to satisfy the reciprocal theorem. Values calculated using the BSM for dielectric randomly rough surfaces compare well with those of the integral equation model (IEM) and with experimental data, showing that the BSM accuracy is acceptable and its range of validity is similar to that of IEM while the BSM expression is simpler than that of IEM.展开更多
By using iterative method to solve the vector radiative transfer equation of discrete scatterers with randomly rough under-boundary, the back-scattering coefficient is derived, and is applied to the two-scale model of...By using iterative method to solve the vector radiative transfer equation of discrete scatterers with randomly rough under-boundary, the back-scattering coefficient is derived, and is applied to the two-scale model of sea surface with foam scatterers driven by strong wind. By employing the modified probability density function of Cox and Munk's, and Pierson's sea spectrum, numerical results of polarized back-scatter ing are calculated. The functional dependence on wind speed and direction, observation angle, polarization and other parameters are discussed, and theoretical results are favorably matched with experimental data.展开更多
基金supported by the National Natural Science Foundation of China(60971091,40637033)the State Key Laboratory of Remote Sensing Science(2009KFJJ011)
文摘In China's first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness,and global evaluation of 3He content.To analyze the modeling of microwave radiative transfer from three-layered media of lunar surface,some factors,such as the cratered lunar surface roughness,scattering of regolith particulate medium with temperature profile,are discussed.Based on the statistics of the lunar cratered terrain and using Monte Carlo (MC) method,the cratered lunar surfaces are numerically generated.The triangulated network is utilized to divide the undulated lunar surface into discrete triangle meshes with the size 10 m as a digital surface topography.The reflectivities of each plane mesh are calculated,and the average reflectivity for all MC-realized lunar surfaces is obtained.It is found that under the spatial resolution of 30 km×30 km of Chang-E 1 radiometer observation,the lunar surface can be well modeled as a flat surface.It makes the predominance of the parameters,such as the regolith layer thickness and stratified structures,to be studied.Using the radiative transfer equation of stratified media with dense scatterers,the scattering coefficient of the regolith particulate medium is found negligible,and the emission is mainly governed by the absorptive property of the medium.Brightness temperature of multi-layered media,i.e.lunar soil,regolith layer with temperature profile and underlying rock media,are derived and calculated,and relevant main factors to affect the modeling and emission simulation are analyzed.
基金Supported by the National Natural Science Foundationof China(No.498710 5 7)
文摘A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common randomly rough surfaces without obvious two-scale characteristics, a scale-compression filter can divide the auto-correlation spectrum into two parts with different correlation lengths. The Kirchhoff approximation and the small perturbation method are used to obtain the surface field, then a bistatic scattering model, the bi-spectrum model (BSM), is used to derive an explicit expression from the surface field. Examples using the integral equation model (IEM), finite difference of the time domain (FDTD) method, and BSM show that the BSM accuracy is acceptable and its range of validity is similar to IEM. BSM can also be extended to a scattering model for dielectric randomly rough surfaces.
基金Supported by the National Natural Science Foundationof China(Nos.4 0 1710 71and4 98710 5 7)
文摘The bistatic scattering model is offen used for remote microwave sensing. The bi-spectrum model (BSM) for conducting surfaces was used to develop a scattering model for dielectric randomly rough surfaces to estimate their bistatic scattering coefficients. The model for dielectric rough surfaces differs from the BSM for a conducting surface by including Fresnell reflection and transmission from dielectric rough surfaces. The bistatic scattering coefficients were defined to satisfy the reciprocal theorem. Values calculated using the BSM for dielectric randomly rough surfaces compare well with those of the integral equation model (IEM) and with experimental data, showing that the BSM accuracy is acceptable and its range of validity is similar to that of IEM while the BSM expression is simpler than that of IEM.
基金This work was supported by the National Natural Science Foundation of ChinaFok Ying Tung Education Foundation
文摘By using iterative method to solve the vector radiative transfer equation of discrete scatterers with randomly rough under-boundary, the back-scattering coefficient is derived, and is applied to the two-scale model of sea surface with foam scatterers driven by strong wind. By employing the modified probability density function of Cox and Munk's, and Pierson's sea spectrum, numerical results of polarized back-scatter ing are calculated. The functional dependence on wind speed and direction, observation angle, polarization and other parameters are discussed, and theoretical results are favorably matched with experimental data.
