Journal of Glaciology最新文献

We demonstrate that a ~20 km long valley glacier in the St. Elias Mountains, Yukon, can experience both partial and full surges, likely controlled by the presence of a topographic constriction and the formation and drainage of supraglacial lakes. Based on analysis of air photos, satellite images and field observations since the 1940s, we identify a full surge of ‘Little Kluane Glacier’ from 2013 to 2018, and a partial surge of just the upper north arm between 1963 and 1972. Repeat digital elevation models and velocity profiles indicate that the recent surge initiated from the upper north arm in 2013, which developed into a full surge of the main trunk from 2017 to 2018 with peak velocities of ~3600 m a−1 and frontal advance of ~1.7 km from May to September 2018. In 2016, a mass movement from the north arm to the main trunk generated a surface depression in a region immediately downstream of a topographic constriction, which promoted the formation and rapid drainage of supraglacial lakes to the glacier bed, and likely established the conditions to propel the initial partial surge into a full surge. Our results underscore the complex interplay between glacier geometry, surface hydrology and topography required to drive full surges of this glacier.

This study investigates the geodetic mass balance of nearly all glaciers in the Ladakh region, which are crucial for local water security. Utilizing multiple digital elevation models from 2000 and 2021, we estimate glacier mass balances. Climatic drivers of glacier mass balances are explored using ERA5-Land reanalysis data, evaluated by in situ climate data. The study also examines the role of nonclimatic (morphological) variables on glacier mass balances. Results indicate Ladakh glaciers experienced negative mass balances during 2000–2021, with significant spatial variability. Western Ladakh glaciers lost slightly higher mass (−0.35 ± 0.07 to −0.37 ± 0.07 m w.e. a−1) than eastern Ladakh glaciers (−0.21 ± 0.07 to −0.33 ± 0.05 m w.e. a−1). While warming is the main driver of widespread mass loss in Ladakh, the spatial variability in mass loss is attributed to changes in regional precipitation and glacier morphological settings. Eastern Ladakh glaciers, being smaller and at higher elevations, experience lower mass loss, whereas western Ladakh glaciers, larger and at lower elevations, are more susceptible to the impact of temperature, resulting in higher mass loss. The study underscores the potentially greater vulnerability of western Ladakh glaciers to a warming climate compared to their eastern counterparts.

One fifth of Earth's volcanoes are covered by snow or ice and many have active geothermal systems that interact with the overlying ice. These glaciovolcanic interactions can melt voids into glaciers, and are subject to controls exerted by ice dynamics and geothermal heat output. Glaciovolcanic voids have been observed to form prior to volcanic eruptions, which raised concerns when such features were discovered within Job Glacier on Qw̓elqw̓elústen (Mount Meager Volcanic Complex), British Columbia, Canada. In this study we model the formation, evolution, and steady-state morphology of glaciovolcanic voids using analytical and numerical models. Analytical steady-state void geometries show cave height limited to one quarter of the ice thickness, while numerical model results suggest the void height h scales with ice thickness H and geothermal heat flux $dot {Q}$ as $h/H = a H^b dot {Q}^c$, with exponents b = −n/2 and c = 1/2 where n is the creep exponent. Applying this scaling to the glaciovolcanic voids within Job Glacier suggests the potential for total geothermal heat flux in excess of 10 MW. Our results show that relative changes in ice thickness are more influential in glaciovolcanic void formation and evolution than relative changes in geothermal heat flux.