Patterns in snow depth maximum and snow cover days during 1961-2015 period in the Tianshan Mountains, Central Asia

The patterns of snow accumulation and ablation were largely influenced by climate change. Current studies on the snow cover characteristics were mainly based on remote sensing retrievals in the Tianshan Mountains, however, they suffered from short record observations. This study quantified the climatology and variations in snowpack patterns related to snow depth from 1961 to 2015 at 48 meteorological stations across the Tianshan Mountains, spanning the elevations from 312 to 3543 m asl. Moreover, this study analyzed the contribution of the air temperature and precipitation during snow accumulation season to snow onset day, as well as the contribution of effective daily > 0 degrees C accumulative temperature and snow depth maximum during snowmelt season to snow end day, respectively. The results showed that the snow depth maximum and snow cover days exhibited similar distribution, i.e., decreasing pattern in a northwest-to-southeast direction. Significant trend toward a shortened snow cover days was identified by 2.7 days decade(-1) at the high altitude of the north slope, although it exhibited a non-significant increasing trend in low-middle altitude regions. A higher snow depth maximum was observed mainly in the north slope by 2.08 cm decade(-1) without any significant elevation-dependency. There existed a positive sensitivity of snow onset day to air temperature with 0.64 days degrees C-1 during snow accumulation season, but an opposite sensitivity of snow end day to effective accumulative temperature with 0.82 days degrees C-1 during snow melt season. In addition, a positive sensitivity of snow end day to snow depth maximum was revealed with 1.84 days cm(-1) during snowmelt season.