Physical Characteristics of Forest Snow in the Western Tianshan Mountains,China

The special physical characteristics of snow cover have great influences on the ice-snow hydrological process,snow ecosystem and different scale climate systems.Presently,the physical characteristics of snow cover in the forest are less investigated,so it is meaningful to measure the height,sedimentation rate,density and water content of the seasonal snow in the forest of picea schrenkiana in the Tianshan Mountains.The results show that the snow depth under crown is less than the observation site,the sedimentation rate of snow under crown is less than the observation site,and the rate in the stable period is less than the snowmelt period.The snow density under the tree is significantly lower than the observation site.The snow density of the upper and bottom layers is smaller than the middle layers.The maximum value of snow density is located in the firn-snow layer under the tree,but the maximum value is located in the coarse-grained snow layer in the open area.The snow density in the snowmelt period is greater than in the stable period.In the stable period,the profile of snow liquid water with depth has a single peak in the observation site,the liquid water content of the coarse-grained snow is the highest,and the liquid water content increases with depth under the tree.In the snowmelt period,the liquid water content of the fine-grained snow is the highest,the liquid water content of the newly fallen snow has the minimum value.The snow liquid water content in the open ground decreases with depth from fine-grained snow to mid-grained snow,and increases with depth from coarse-grained snow to depth hoar,while the water content decreases from fine-grained snow to depth hoar under the tree.The diurnal variation is to decrease with depth in the stable period,and the variation of snow liquid water content in open ground is greater than that under the tree.The maximum diurnal variation is in the layer of fine-grained snow and decreases with depth;the liquid water content of new snow and firn-snow in open ground is greater than that under the tree,but the layer of coarse-grained snow and depth hoar are on the contrary.