Effect Of Black Carbon On The Reflection Properties Of Snow Cover Polarization

As one of the surface materials,snow cover is an important indicator for long-term monitoring of environmental and ecological changes due to its active characteristic parameters.Snow cover up to 30% of the world’s surface.The absorption particles,especially black carbon(BC),as important research objects,not only directly affect the strength of snow albedo and snow melt intensity,but also further affect the global radiation balance,spatial and temporal distribution of water resources and soil moisture.As a monitoring method with the advantages of large range,real-time,fast and low cost,remote sensing has been widely used in the study of snow feature parameter judgment.With the continuous development of snow remote sensing technology,various model algorithms proposed by researchers have enriched the judgment methods of black carbon absorbed in snow.It is important to increase the polarization reflection of snow in full Angle to improve the accuracy of black carbon inversion.This paper is based on multi-angle spectral data of snow with different degrees of black carbon pollution.By analyzing and controlling experimental measurement conditions such as zenith Angle,azimuth Angle,polarization state and pollution degree,spectral characteristics with diagnostic significance are obtained and causes are analyzed.The research shows that: 1 because of the slight fluctuation on the surface of pure snow,the backscattering is higher than the forward scattering,while the spectral distribution of snow containing black carbon is higher than the backscattering due to the strong absorption characteristics of black carbon.2 Because the absorption of black carbon in visible light is stronger than that in near-infrared,Therefore,the decrease range of the reflectance of visible band is greater than that of the polarization reflectance of NIR.3 snow meets the law of increasing the detection zenith Angle,which is related to the decrease of multiple scattering when the detection zenith Angle increases.Furthermore,when azimuth Angle of 180° and zenith Angle of 60°are determined by orthogonal test,the reliability of polarization reflection spectrum data of snow in visible band is the best,which can simplify the experimental measurement process by 50% and the calculation amount of experimental data by nearly 78%.By comparing the bidirectional reflectance coefficient(BRF)and light intensity parameter reflectance coefficient(Ip RF)of snow with different black carbon content,it can be seen that the spectral and distribution characteristics of the two are consistent,and Ip RF can replace BRF in the study of the influence of black carbon on the spectral characteristics of snow.In this paper,through the control experiment and the orthogonal experiment of qualitative and quantitative studies of black carbon pollution level snow polarization reflection data,prove the feasibility of application Ip RF data instead of BRF data,determine the diagnosis significance of snow polarization spectral reflectance characteristics and analyzes the reason,discussed the snow polarization spectral reflectance best measuring conditions,It provides a new method to achieve fast and easily obtain snow spectrum data with different pollution levels.