Impacts of landscape and climatic factors on snow cover in the Altai Mountains, China

Snow properties and their changes are crucial to better understanding of hydrological processes, soil thermal regimes, and surface energy balances. Reliable data and information on snow depth and snow water equivalent (SWE) are also crucial for water resource assessments and socio-economic development at local and regional scales. However, these data are extremely limited and unreliable in northern Xinjiang, China. This study thus aims to investigate spatial variations of snow depth, SWE, and snow density based on winter snowfield surveys during 2015 through 2017 in the Altai Mountains, northwestern China. The results indicated that snow depth (25-114 cm) and SWE (40-290 mm) were greater in the alpine Kanas-Hemu region, and shallow snow accumulated (9-42 cm for snow depth, 26-106 mm for SWE) on the piedmont sloping plain. While there was no remarkable regional difference in the distribution of snow density. Snow property distributions were strongly controlled by topography and vegetation. Elevation and latitude were the most important factors affecting snow depth and SWE, while snow density was strongly affected by longitude across the Altai Mountains in China. The influence of topography on snow property distributions was spatially heterogenous. Mean snow depth increased from 13.7 to 31.2 cm and SWE from 28.5 to 79.9 mm, respectively, with elevation increased from 400 to 1000 m a.s.l. on the piedmont sloping plain. Snow depth decreased to about 15.1 cm and SWE to about 28.5 mm from 1000 to 1800 m a.s.l., then again increased to about 98.1 cm and 271.7 mm on peaks (2000 m a.s.l.) in the alpine Kanas-Hemu. Leeward slopes were easier to accumulate snow cover, especially on north-, east-, and southeast-facing slopes. Canopy interception was also the cause of the difference in snow distribution. Snow depth, SWE, and snow density in forests were reduced by 8%-53%, 2%-67% and -4% to +48%, respectively, compared with surrounding open areas. Especially when snow depth was less than 40 cm, snow depth and SWE differences in forests were more exaggerated. This study provides a basic data set of spatial distributions and variations of snow depth, SWE and snow density in the Altai Mountains, which can be used as an input parameter in climate or hydrological models. These first-hand observations will help to better understand the relationship between snow, topography and climate in mountainous regions across northern China and other high-mountain Asian regions.

Automated summary

This study investigated the spatial variations of snow depth, SWE, and snow density in the Altai Mountains of northwestern China from 2015 to 2017. Results showed that snow properties were strongly controlled by topography and vegetation, with elevation and latitude being the most important factors affecting snow depth and SWE, while snow density was strongly influenced by longitude.