Distribution and Variation of Spring Snow Cover in Laohugou Watershed of the Qilian Mountains

In order to understand the physical process of snow cover and its feedback to climate system,it is necessary to study the properties of snow cover.In this paper,the distribution and variation of snow cover in spring in Laohugou watershed of the Qilian Mountains was investigated.The snow cover properties,i.e.,snow depth,snow density,snow liquid water content,snow reflectance,snow surface albedo,snow grain size and temperature,were measured using some advanced instruments during the observation.In addition,snow cover profile was measured in snow pits.Snow cover depth measurement found that the spatial distribution of snow cover depth is quite various.The snow cover in shaded area is deeper than that on other slopes.The measured snow spectral reflectance shows a distinct dependence on snow grain size,snow type,snow depth,snow density,snow liquid water content and surface roughness.Snow surface albedo was measured by automatic weather station.When snow depth reaches a certain value,the snow cover always has heat preservation effect.There was a temperature profile with a temperature inversion layer depending on snow cover depth and surface temperature.Within a day,new snow density variation is consistent with water content variation.