1State key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou 730000, China
2University of Chinese Academy of Sciences, Beijing 100049, China
3College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
4National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309-0449, USA
5Key Laboratory of Western China's Environmental Systems (Ministry of Education), Lanzhou University, Lanzhou 730000, China
Abstract. Snow density is one of the basic properties used to describe snow cover characteristics, and it is a key factor for retrieving snow depth and snow water equivalent, which are critical for water resources assessment and modeling inputs. In this study, we used long-term data from ground-based measurements to investigate snow density climatology and its spatiotemporal variations across the former Soviet Union (USSR) from 1966 to 2008. The results showed that the long-term monthly mean snow density was approximately 0.194 ± 0.046 g cm−3 over the study area. The maximum and minimum monthly mean snow density was ∼ 0.295 g cm−3 in June, and 0.135 g cm−3 in October, respectively. Maritime snow had the highest monthly mean snow density, while taiga snow had the lowest. The higher values of monthly snow density were mainly located in the European regions of the former USSR, in Arctic Russia, and in some regions of the Russian Far East, and the lower snow density occurred in central Siberia. Significant increasing trends of snow density from September through June of the next year were observed, however, the rate of the increase varied with different snow classes. The long-term (1966–2008) monthly and annual mean snow densities had significant decreasing trends, especially during the autumn months. Spatially, significant positive trends in monthly mean snow density lay in the southwestern areas of the former USSR in November and December and gradually expanded in Russia from February through April. Significant negative trends mainly lay in the European Russia and the southern Russia. Snow density decreased with elevation, at about 0.004 g cm−3 per 100 m increase in elevation. This same relationship existed for all snow classes except for maritime and ephemeral snow.