我国冬季季节性积雪反照率的观测与模拟——以东北地区为例

应用了一种新的模式spectral albedo model for dirty snow，简称SAMDS，研究了不同参数对于积雪反照率的影响，结果表明：在天顶角固定为60°的条件下，新雪的粒径从50 μm增大到800 μm，使其宽波段反照率从0.92减小到0.78；相对于非球形的雪粒，球形雪粒的积雪反照率更低；吸光性颗粒物对光谱反照率的影响主要在可见光和紫外波段。此外，雪粒径的增大能使吸光性颗粒物的光吸收效应增强。结合东北地区的实测数据，我们发现SAMDS模拟的积雪宽波段反照率与实测结果较为一致。同时，SAMDS模式模拟结果表明，在东北地区，积雪中0.1~1 μg·g^-1的黑碳浓度导致积雪宽波段反照率减少2%~8%，造成的瞬时辐射强迫为9~35 W·m^-2。

Observation and simulation of seasonal snow albedo during winter in China: taking Northeast China as an example

A new radiative transfer model (Spectral Albedo Model for Dirty Snow, or SAMDS) based on the asymptotic radiative transfer theory was applied to simulate the spectral albedo of snow due to different parameters, such as solar zenith angle, snow grain size, impurities concentrations, and mass absorption cross-section of impurities. The results show that the SAMDS model produced a snow broadband albedo in the range of 0.95~0.75 for fresh snow, with a snow grain optical effective radius increasing from 50 μm to 800 μm. The snow albedo for spherical snow grains is lower than that for the other two shapes. In addition, the variations of spectral albedo of snow in the infrared is mainly dominated by the snow grain size and by the solar zenith angle, also the snow grain shape has a slight effect. Nevertheless, the variations of spectral albedo of snow in the visible and ultraviolet bands is governed largely by the load of pollutants. Moreover, the simulated snow albedo by SAMDS agree well with the observed values. Simultaneously, the modeled broadband albedo decrease by 2%~8% due to 0.1~1 μg·g^-1 of black carbon (BC) in snow with snow grain optical effective radius equal 250 μm, and the associated instantaneous radiative forcing were 9~35 W·m^-2.