Spatiotemporal dipole variations of spring snowmelt over Eurasia

Abstract

Spring snowmelt in Eurasia plays an important role in the climate system and regional water resources. However, there is still a limited understanding of the spatiotemporal characteristics of spring snowmelt in Eurasia and the factors that drive its variations. This study utilized the GlobSnow v3.0 snow water equivalent (SWE) monthly bias-corrected data and defined the spring snowmelt as the difference between the spring peak SWE and the SWE in May, to investigate the spatiotemporal variations of spring snowmelt in mid- and high-latitudes of Eurasia from 1979 to 2018 and identify the factors influencing these changes. Our findings reveal a substantial increase in spring snowmelt over the past four decades, with an average annual increase of 5.76 gigatons (GT) of water equivalent across the entire study region. Approximately 64.71% of the mid-high latitudes of Eurasia exhibits a positive trend in spring snowmelt, and 22.49% of the area shows a statistically significant increase (p < 0.05). Spatially, a dipole pattern of spring snowmelt variation is observed, with an increase in the eastern regions and a decrease in the western regions. The decline in spring snowmelt in western Eurasia is attributed to a decrease in snow accumulation during the previous season, while the increase in spring snowmelt in the eastern high latitudes is driven by intensified spring melting. In the eastern mid-latitudes, the rise in spring snowmelt is associated with an increase in snow accumulation during the previous season. Furthermore, our study highlights the influence of near-surface air temperature, rainfall ratio, and total precipitation during both the spring and snow accumulation seasons on spring snowmelt variability. Our results elucidate the spatiotemporal characteristics of spring snowmelt and emphasize the role of climate factors in modulating snow accumulation and subsequent spring melting patterns in the mid- and high-latitudes of Eurasia.