How do snow cover fraction change and respond to climate in Altai Mountains of China?

Investigating the spatial and temporal changes in snow cover over mountain areas is significant for understanding the impact of regional climate variability. In this study, using cloud-removed snow cover data, which are generated based on Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow cover products, the spatiotemporal changes of snow cover fraction (SCF) and its relationship with temperature and precipitation changes from 2002 to 2020 were examined over Altai Mountains, China. The results demonstrate that the distribution and changes of SCF are highly spatiotemporally heterogeneous. Within a year, the maximum SCF occurs in January at 98.6%, and the minimum appears in July at 8.7%. The annual-mean SCF shows an increasing trend at 0.09%center dot annum(-1), owing to the significantly increasing SCF in the snow accumulation period at 0.5%center dot annum(-1) and the decreasing SCF in the snow melting period at -0.2%center dot annum(-1). The SCF distribution, as well as its interannual change, is greatly influenced by elevation. During the snow cover period, a positive linear correlation between SCF and elevation is found at 0.02%center dot m(-1) (p < .01). The annual-mean SCF decreases in the area below 1,200 m, whereas it increases in the area above 1,200 m. Accordingly, the elevation-dependent SCF results in various SCF distributions on different slopes and watersheds. The SCF shows an apparent pattern in different aspects, with similar SCFs between the north and east aspects and between the west and south aspects but a difference between the northeast aspects and the westsouth aspects. The SCF is negatively correlated with air temperature (r = -0.74, p < 0.01) and positively correlated with precipitation (r = 0.74, p < 0.01). In addition, temperature shows a significant and larger correlation with SCF in both the snow accumulation and melting periods, indicating the major factor of temperature for the changes in SCF.

Automated summary

This study investigates the spatiotemporal changes in snow cover over Altai Mountains in China from 2002 to 2020. The results show that the distribution and changes of snow cover fraction (SCF) are highly heterogeneous. The SCF is influenced by elevation and shows a positive correlation with precipitation and a negative correlation with air temperature. Temperature is found to be the major factor affecting the changes in SCF.