Hydrothermal combination and geometry control the spatial and temporal rhythm of glacier flow

Highlights: • Eight years of continuous in-situ observations for Baishui River Glacier No.1. • Baishui River Glacier No.1 has experienced significant mass loss and rapid retreat. • First comprehensive measurement of spatio-temporal velocity. • Glacier velocities are influenced by hydrothermal conditions and glacier geometry. The dynamic response of glacier to atmospheric change has varied both spatially and temporally. While some of this variability is likely related to regional climate signals, the geometry of this particular glacier also appears to be important. In this study, we investigated the hydrothermal conditions and geometric controls on the temporal and spatial evolution of Baishui River Glacier No.1's velocity from 2012 to 2019. To do this, we combined field investigations and remote sensing observations to measure the velocity of the glacier, and factors controlling this velocity. Annual changes showed that, from 2012 to 2019, the Baishui River Glacier No. 1 experienced continuous shrinkage, accompanied by decreasing ice velocities. Seasonal changes showed that the glacier velocity during the monsoon period was significantly higher than during the non-monsoon period. Spatially, the glacier's dynamic variability decreased toward its terminus, but increased toward the upper reaches of the glacier, along a longitudinal axis. We would suggest that the interannual velocity variation of Baishui River Glacier No.1 corresponded to thinning of the glacier, which in turn affected its gravitational force. Given that surface melt-induced basal lubrication, basal friction controlled by freezing rate, and dynamic thickening can alter seasonal patterns of movement, these variations may be important for understanding the seasonal evolution of this, and other glaciers. Our results further indicated that glacier width, slope, surface meltwater and crevasses were important constraints on any spatial movement patterns.