Abstract: Snowpack is an important source of water resources in arid area in northwest China. In spring,dust storm weather occurs frequently in the basins around the Tianshan Mountains. Dust deposition on snow cover surface from dust storm can reduce the reflectance of snow cover,increase the solar radiation absorption on snow cover surface,and accelerate snowmelt. It is necessary to study the effects of deposited dust on the dynamic change of snowpack in the Tianshan Mountains for better water resources management in the region. In this study,a simulation experiment of the influence of dust deposition on the dynamic change of snowpack in snowmelt season was carried out at the Tianshan Station for Snow and Avalanche Research. Four treatments,i.e. the natural conditions,2 g·m^-2,4 g·m^-2 and 8 g·m^-2 dust deposition with three replicates,were designed for the field experiment. The experiment was started on March 4 and ended on March 11. After observing and analyzing the physical characteristics of snowpack,the results indicated that snowmelt in the snowpack was significantly affected by dust deposition. The snow grain size on snow surface was increased with the time,and the more dust deposition there was,the larger the snow grain size but the lower the snow reflectance would be. The snowmelt rates under the treatments with 2 g·m^-2,4 g·m^-2 and 8 g·m^-2 dust deposition were increased by 22.36%,46.05% and 76.90% compared with that of natural snowpack,respectively. The results of the study could provide the references for simulating the dynamic change of snowpack and managing water resources in arid area in northwest China.

Key words: dust deposition, snowpack, snow grain size, spectrum, snow cover temperature, snowmelt rate, Tianshan Mountains