Simulation of Spectral Albedo Mixing of Snow and Aerosol Particles
CHEN Wen-qian1, 2, DING Jian-li1, 2*, WANG Xin3, PU Wei3, ZHANG Zhe1, 2, SHI Teng-long3
1. Xinjiang Common University Key Lab of Smart City and Environmental Stimulation, Xinjiang University, Urumqi 830046, China
2. Key Laboratory of Oasis Ecology, Ministry of Education, Urumqi 830046, China
3. Key Laboratory for Semi-Arid Climate Change, Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Abstract：Aerosol particles of Black carbon in the snow cause a significant decrease in the albedo spectrum of the snow, which results in climatic radiation changes seriously, and will delay or advance the snow melting time, badly affecting the characteristics of surface runoff and processes of water cycle in the arid region. This problem is receiving increasing attention in ecological hydrology issues in the arid region. The data of field measurement were obtained by ASD spectrometer, Snow Folk and HR-1024 external field spectrum radiometer. SNICAR model was used to simulate the snow spectrum spectral characteristics under different parameters. Discussed the sensitivity of BC and snow particle size in different spectral ranges. The results showed that: In the snow spectral curve, the zenith angle changes from 0° to 80°, the albedo at 600 nm in the visible spectrum increases by 0.045, and the albedo at 1 000, 1 200 and 1 300 nm in the near-infrared band increases by 0.16, 0.225 and 0.249, respectively. The zenith angle is at 60°, when snow particle size increases from 100 to 800 μm, the albedo reduction can reach 0.15, and snow particle size in the range of 100~300 μm is significantly higher than the albedo in the range of 400~800 μm. And the increase of the snow particle size can enhance the absorption effect of the light spectrum absorbing particles; Different BC concentrations have little effect on the spectral albedo in the near-infrared region, but are mainly concentrated in the visible light band. At 800 and 1 100 nm, the BC concentration of 5 μg·g-1 reduces the spectral albedo by 0.13. The BC of 5 μg·g-1 can reduce the spectral albedo at 350 and 550 nm by 0.25 and 0.23. Compared with the different snow sizes, the decrease of BC concentration on the broad-band albedo of snow spectrum can be found in BC. In the case of the increase in the particle size of the snow, the light absorption effect of BC is increased, and at the higher concentration, the more the absorption increases; from the spectral index, the BC is sensitive in the visible light range of 350~740 nm, and the correlation coefficient is higher; The snow size is sensitive in the near-infrared band 1 100~1 500 nm, especially around 1 000 and 1 300 nm. The correlation between BC and snow particle size in the sensitive band of the snow spectral curve is high. Finally, the snow albedo simulated by the model is compared with the measured data. The R2 is 0.738, and the simulation effect is good. It can lay a data foundation for the study of the snow albedo in the arid region.
Key words：Arid zone; Snow spectral albedo; Black carbon; Snow particle size; Spectral index
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