Simulation On Radiance From Atmospheric Limb Scattering And Sensitivity Analysis

Atmosphere, the global complicated system, is very important to the life-beings on the earth. Long-term observation shows that the activities of human-beings are changing the composition of the atmosphere, and thus cause the global environmental degradation, such as Ozone hole, global warming and forest degradation. These destructions can be mended by the research of atmosphere. Radiance from limb scattering has be simulated, and its sensitivity is analyzed, with the supporting of the national'863'Project, aims at the retrieval of the atmospheric ozone profile using the the atmospheric limb scattering data.There are three satellite-borne atmospheric detection modes, compared with nadir and occultation mode, the limb mode has both high spatial resolution and global coverage. The SCIATRAN is one of the much mature radiative transfer simulation models, providing two modes of nadir and limb simulation. The SCIATRAN model includes the most advanced spherical atmospheric model, and has a more detailed parameters input system.More than one hundred parameters of SCIATRAN are classified into six types, five of them are selected, including observation geometry, cloud, trace gas, aerosol and land surface properties parameters as the influencing factors of radiance. The simulated parameters and limb condition are decided by research target and Odin/OSIRIS information, 27 parameters and 328 values are selected in all. The radiance from limb scattering of eatch selected parameters are simulated, and validated by published result and atmospheric radiative transfer theory.Two schemes have been designed for the sensitivity analysis of the radiance based on the number of parameter values, including wavelength, tangent heights, values of parameters and simulated radiances.The sensitivities of radiance from limb scattering to selected parameters are analyzed finally.The study shows that all of the selected parameters in five categories are the sensitive factors of the limb radiance, except the concentration of carbon dioxide and firedamp. The effects of each sensitive factor on radiation are variational, but also similar from whole aspect.In background conditions, the visibility of the boundary layer, stratospheric aerosol type in aerosol parameters, and scattering coefficient, optical thickness in cloud parameters have more obvious effects on the the radiance from limb scattering, oppositely, the observation geometry and land surface characteristic parameters have a slight affect. Some sensitives enhance the radiance, like the selected cloud parameters, aerosol optical depth scaling and albedo, but also some will weaken the radiance,for example aerosol boundary layer visibility and humidity, troposphere humidity and trace gas consistence.The changes of tangent height and wavelength will make the influence variational. The radiance are less affected when the tangent height raises by the sensitives except aerosol, and the change is smaller in UV bands.The different aerosol layer parameters have theirs obvious effect at different height.The radiance changing trend to observation geometry and land surface characteristic parameters are both independent of the tangent height, and to some sensitives have intricate variety with the change of the tangent height.In background conditions, the trace gases, including ozone, oxygen, water vapor and nitrogen dioxide, affect the radiance only in their own absorption band. According to this conclusion, their concentration and spatial distribution can be obtained using the radiance of absorption bands, or eliminated the interference using the no absorption bands.