Characteristics of the spatiotemporal differences in snowmelt phenology in the Northern Hemisphere

Abstract

Study region

The Northern Hemisphere.

Study focus

Snowmelt processes are critical components of the hydrological cycle, significantly influenced by climate change. This study analyzes spring-summer snowmelt phenology and rates (1991–2022) using ERA5-Land data, focusing on spatiotemporal trends in snowmelt duration, rate heterogeneity, and drivers under climate change.

New hydrological insights for the region

The snowmelt period length (LSMD) shortens significantly (−0.129 day/year), notably in mid-high latitude North America and temperate Eurasia, while permanent snow zones show prolonged LSMD from intensified ablation. Snowmelt rates exhibit marked spatial heterogeneity: latitude-dependent dynamics peak in temperate-subarctic transition zones (55°-65°N), altitude-driven rates decline below 2800 m but rebound above 3400 m, and longitudinal patterns highlight higher rates in high-longitude regions. Maritime (MT) undergoes the most rapid and prolonged melting, contrasting with slower rates in forested/agricultural areas due to vegetation interactions. Dominantly low-intensity snowmelt prevails, yet transitions to higher intensities are pronounced at 45°-60°N. Regional “mean-extreme decoupling” implies deep snowpack energy storage-release mechanisms. These findings reveal complex, spatially divergent snowmelt responses to warming, critical for predicting hydrological and water resource impacts across the hemisphere.