Study On Albedo Property Of Rough Oil Surface Based On BRDF

With the continuous development of our country’s "Maritime Silk Road" and “Ocean Strong Power” strategic policy.The advancement of maritime transportation and ocean engineering equipment also motivates the scale of human-related marine activities.Oil spills have become a problem that negatively affects the oceanic environment and maritime transportation.Optical remote sensing technology is a potential method to monitor oil spills by analyzing the reflectance spectra of oil-polluted and clean water surface.In this thesis,a numerical model for the reflectance of a rough oil surface is constructed by combining Fresnel reflection and bidirectional reflectance distribution function(BRDF).The way that visible light is reflected from the rough diesel fuel surface is quantitatively described and discussed based on the reflection theory of electromagnetic waves.The simulation result of the proposed model shows reasonable agreement with experimental measurements.With reliable prediction and a low computational complexity,the proposed model is expected to provide a theorical basis for rapid detection of oil spills on rough sea surfaces using optical remote sensing technology.The specific research content of this thesis is as follows:(1)Numerical model the reflectance of oil film sample in the rough surface has been constructed.The mechanism of visible light reflection and scattering have studied.Numerical modeling the reflectance of oil film sample in the rough surface based on BRDF and Studying the reflection and scattering mechanisms of visible light across rough sea-surface.By comparing the validity of experimental results,this model has fast calculation speed and the reflectance of the light oil film on the sea surface can be calculated accurately.the reflection properties of the light oil film on the rough sea surface can be well explained.The model facilitates further oil spill monitoring and mapping.(2)An experimental environment for BRDF measurement of oil film on real rough sea surface was established.The spectral properties of oil film(diesel oil,ship fuel oil,Brazilian and Saudi crude oil)with different sea surface roughness were analyzed.The obvious spectral characteristics of BRDF for oil film detection are obtained,which further improves the reliability of oil product identification in the current oil spill sea area.(3)The grayscale data,relative reflectance and absolute reflectance curves of oil film reflectance spectrum were processed and analyzed,and a significant region selection method suitable for push-sweep hyperspectral sensor was adopted.By analyzing the reflectance spectral curves of rough sea surface oil film samples,the significant absorption peak frequency with visible wavelength of 390～750nm was located,which provides data supports for the selection of characteristic spectrum of remote sensing oil spill monitoring.This thesis proposed a method for calculating the reflectance of offshore oil spill under complicated sea conditions.The results can be applied to the refined emergency response in the offshore oil spill area.It provided basic guidance for maritime environment restoration and management.