Mass balance of White Glacier, Axel Heiberg Island, N.W.T., Canada, 1960–91

ABSTRACT. To better understand the processes controlling recent mass loss of peripheral glaciers and ice caps in northwestern Greenland, we measured surface mass balance (SMB), ice velocity and nearsurface ice temperature on Qaanaaq Ice Cap in the summers of 2012-16. The measurements were performed along a survey route spanning the terminus of an outlet glacier to the upper reaches (243-968 m a.s.l.). The ice-cap-wide SMB ranged from −1.10 ± 0.29 to −0.13 ± 0.26 m w.e. a −1 for the years from 2012/13 to 2015/16. Mass balance showed substantially large fluctuations over the study period under the influence of summer temperature and snow accumulation. Ice velocity showed seasonal speedup only in the summer of 2012, suggesting an extraordinary amount of meltwater penetrated to the bed and enhanced basal ice motion. Ice temperature at a depth of 13 m was −8.0°C at 944 m a.s.l., which was 2.5°C warmer than that at 243 m a.s.l., suggesting that ice temperature in the upper reaches was elevated by refreezing and percolation of meltwater. Our study provided in situ data from a relatively unstudied region in Greenland, and demonstrated the importance of continued monitoring of these processes for longer timespans in the future.

Section: Methodsmentioning

confidence: 99%

“…Following the values estimated by previous Greenland studies (±0.23 to ±0.28 m w.e.) (Bauer, 1961; Braithwaite, 1986; Cogley and others, 1996; Machguth and others, 2016), we assumed ±0.25 m w.e. as an uncertainty arising from the SMB inhomogeneity.…”

Section: Methodsmentioning

confidence: 99%

Surface mass balance, ice velocity and near-surface ice temperature on Qaanaaq Ice Cap, northwestern Greenland, from 2012 to 2016

Tsutaki

Sugiyama²,

Sakakibara

et al. 2017

“…in the Expedition Fiord region of Axel Heiberg Island, Nunavut. The mean annual temperature of the region is ~−20°C and mean precipitation at the highest elevations is ~370 mm a −1 , based upon a 41-year snow pit record of annual accumulation on Müller Ice Cap (Cogley and others, 1996). Since the onset of mass-balance observations in 1960, the mean decadal ELA has risen from 1000 m a.s.l.…”

Section: Site Descriptionmentioning

confidence: 99%

Changing contribution of peak velocity events to annual velocities following a multi-decadal slowdown at White Glacier

Thomson

Copland

2017

As the focus of intensive glaciological studies in the 1960–70s, White Glacier on Axel Heiberg Island, Canada, has played an important role in understanding the dynamics of mostly-cold polythermal glaciers in the high Arctic. In this study, we examine the magnitude, duration and timing of peak velocity events in the summers of 2013–15 using continuous dual-frequency GPS observations, and compare them with similar measurements made in 1968. Summer speed-up events in 1968 and 2014, in which ice velocities reached 200% above winter values, were found to occur in conjunction with formation and drainage of an ice-marginal lake. Despite thinning of the glacier by >20 m and a decrease in annual surface velocities of 15–35% since the 1960s, the relative magnitude and duration of these peak events has increased, particularly at lower elevations, in comparison with the observations at the same locations many decades ago. Given the long-term slowdown of the glacier, the relative contribution of summer displacement to the net annual motion has therefore increased significantly, with summer motion over the span of <2 months now accounting for nearly half of the total annual displacement.

“…Though great care was taken in field measurements, these are inevitably affected by large errors. Cogley and others (1996) concluded that errors in fieldwork are of the same order as errors in individual stake readings, and can eventually reach 0.25 mw.e.…”

Section: Mass-balance Methodsmentioning

confidence: 99%

Mass balance of ‘Glaciar Bahía del Diablo’, Vega Island, Antarctic Peninsula

Skvarca¹,

Angelis²,

Ermolin³

2004

Given the pronounced atmospheric warming recorded in recent decades on the Antarctic Peninsula (AP), knowledge of glacier mass balance in this region is especially important for assessing the impact of climatic warming on ice masses. ‘Glaciar Bahía del Diablo’ (GBD) on Vega Island, northeastern AP, is a glacier that terminates on land, so its mass balance is directly linked to climate. GBD is a polythermal outlet glacier, 14.3 km2 in area with an accumulation–area ratio of 0.39. Increased ablation rates and glacier thinning motivated us to select GBD as a test site for mass-balance studies within the region. Calculations based on the stratigraphic annual method yielded a mean annual loss of 0.32 mw.e. a–1 for the annual net mass balance (bn) between 1999 and 2003. A strong correlation was observed between bn and mean summer temperatures, confirming that GBD is highly sensitive to climate. The study of GBD aims at establishing a suitable reference database for ice–climate studies in a region of dramatic changes in Antarctica.