Alpine snow properties analysis based on in-situ measurements in Binggou Watershed of Qilian mountain

Alpine snow properties analysis based on in-situ measurements in Binggou Watershed of Qilian mountain

Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition)

The alpine snow and its melt can dominate local regional climate and hydrology. Some snow models and quantitative remote sensing of snow require abundant field data of snowpack properties for calibration and validation. In the study, the snow properties were measured using some advanced instruments in Binggou Watershed, and then the temporal and spatial relationships of the properties of snowpack were analyzed. With graduated snow sticks, Snow Fork, hand-loupe with scale and so on, the snow spatial distribution, along with other properties such as snow density, snow liquid water content, snow reflectance, snow surface albedo, snow grain size and temperature was measured during December 2007 and March 2008. In addition, also snow profile properties in conjunction with snow pit work were measured and the Snow Equivalent Density (SED) was calculated. Results of snow depth from graduated snow sticks indicate the spatial distribution of snow depth in alpine is quite heterogeneous. The snow in the shade slope is much deeper than that in the solar slope. The liquid water content derived from Snow Fork is lower than 3%. The measurements of snow spectral reflectance firmly demonstrate that the snow reflectance has a strong dependence on the snow grain size, the snow type (contamination) and surface roughness. Snow surface albedo was measured using a portable albedometer. The results show that the snow surface albedo can vary depending upon the surface liquid water content except for latest snowfalls. Results of the snow pit work exhibit different snow vertical structures: fine snow, old snow, ice, and coarse grain snow. When the snow depth is more than 20 cm, the snow is often a heat preservation layer. The snow equivalent density shows little temporal and spatial variance. After calculation, the SED was 0. 16 g/cm3 as calculated.