Ice flux of Plogbreen, a small ice stream in Dronning Maud Land, Antarctica

AbstractAs part of a long-term mass-balance program run by SWEDARP since 1988, a detailed study on Plogbreen, Dronning Maud Land, Antarctica, was undertaken during the austral summer of 2003 to investigate the long-term mass balance. We compare ice outflux, φout, through a cross-sectional gate with ice influx, φin, from the upstream catchment area. The φin is based on calculations of snow accumulation upstream of the gate using data available from published ice-core records. The φout is based on Glen’s flow law aided by thermodynamic modeling and force-budget calculations. Input data from the field consist of measurements of ice surface velocity and ice geometry. The ice surface velocity was measured using repeated differential global positioning system surveying of 40 stakes over a period of 25 days. The ice geometry was determined by 174 km of ground-penetrating radar profiling using ground-based 8MHz dipole antennas. This study presents the collected velocity and geometry data as well as the calculated ice flux of Plogbreen. The results show a negatively balanced system within the uncertainty limits; φout = 0.55 ± 0.05 km3 a–1 and φin = 0.4 ± 0.1 km3 a–1. We speculate that the negative balance can be explained by recent eustatic increase reducing resistive stresses and inducing accelerated flow.

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Accumulation variability derived from an ice core from coastal Dronning Maud Land, Antarctica

Annals of Glaciology ◽

10.3189/172756404781814186 ◽

2004 ◽

Vol 39 ◽

pp. 339-345 ◽

Cited By ~ 21

Author(s):

Marzena Kaczmarska ◽

Elisabeth Isaksson ◽

Lars Karlöf ◽

Jan-Gunnar Winther ◽

Jack Kohler ◽

...

Keyword(s):

High Resolution ◽

Accumulation Rate ◽

Ice Core ◽

Austral Summer ◽

Conductivity Measurement ◽

Ice Cores ◽

Electrical Conductivity Measurement ◽

Regional Pattern ◽

Dronning Maud Land

AbstractA 100 m long ice core was retrieved from the coastal area of Dronning Maud Land (DML), Antarctica, in the 2000/01 austral summer. The core was dated to AD 1737 by identification of volcanic horizons in dielectrical profiling and electrical conductivity measurement records in combination with seasonal layer counting from high-resolution oxygen isotope (δ18O) data. A mean long-term accumulation rate of 0.29 ma–1w.e. was derived from the high-resolution δ18O record as well as accumulation rates during periods in between the identified volcanic horizons. A statistically significant decrease in accumulation was found from about 1920 to the present. A comparison with other coastal ice cores from DML suggests that this is a regional pattern.

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Volume and velocity changes at Mittivakkat Gletscher, southeast Greenland

Journal of Glaciology ◽

10.3189/2013jog13j017 ◽

2013 ◽

Vol 59 (216) ◽

pp. 660-670 ◽

Cited By ~ 15

Author(s):

Sebastian H. Mernild ◽

Niels T. Knudsen ◽

Matthew J. Hoffman ◽

Jacob C. Yde ◽

Edward Hanna ◽

...

Keyword(s):

Mass Balance ◽

Peak Velocity ◽

Dynamic Effect ◽

Snow Accumulation ◽

Surface Velocity ◽

Surface Mass ◽

Ice Surface ◽

Winter Snow ◽

Summer Warming ◽

Velocity Changes

AbstractWe document changes for Mittivakkat Gletscher, the peripheral glacier in Greenland with the longest field-based observed mass-balance and surface velocity time series. Between 1986 and 2011, this glacier changed by −15% in mean ice thickness and −30% in volume. We attribute these changes to summer warming and lower winter snow accumulation. Vertical strain compensated for ∼60% of the elevation change due to surface mass balance (SMB) in the lower part, and ∼25% in the upper part. The annual mean ice surface velocity changed by −30%, which can be fully explained by the dynamic effect of ice thinning, within uncertainty. Mittivakkat Gletscher summer surface velocities were on average 50–60% above winter background values, and up to 160% higher during peak velocity events. Peak velocity events were accompanied by uplift of a few centimeters.

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Dynamics of the Scharffenbergbotnen blue-ice area, Dronning Maud Land, Antarctica

Annals of Glaciology ◽

10.3189/172756404781814177 ◽

2004 ◽

Vol 39 ◽

pp. 417-422 ◽

Cited By ~ 9

Author(s):

Anna Sinisalo ◽

Aslak Grinsted ◽

John Moore

Keyword(s):

Mass Balance ◽

Geometrical Model ◽

Surface Velocity ◽

Geometrical Analysis ◽

Ice Flow ◽

Surface Mass ◽

Ice Surface ◽

Dronning Maud Land ◽

Dip Angle ◽

Ground Penetrating

AbstractGround-penetrating radar (GPR) surveys in Scharffenbergbotnen valley, Dronning Maud Land, Antarctica, complement earlier, relatively sparse data on the ice-flow dynamics and mass-balance distribution of the area. The negative net surface mass balance in the valley appears to be balanced by the inflow. The flow regime in Scharffenbergbotnen defines four separate mass-balance areas, and about 60 times more ice enters the valley from the northwestern entrance than via the narrow western gate. We formalize and compare three methods of determining both the surface age gradient of the blue ice and the dip angles of isochrones in the firn/blue-ice transition zone: observed and dated radar internal reflections, a geometrical model of isochrones, and output from a flowline model. The geometrical analysis provides generally applicable relationships between ice surface velocity and surface age gradient or isochrone dip angle.

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Are longitudinal ice-surface structures on the Antarctic Ice Sheet indicators of long-term ice-flow configuration?

Earth Surface Dynamics Discussions ◽

10.5194/esurfd-2-911-2014 ◽

2014 ◽

Vol 2 (2) ◽

pp. 911-933 ◽

Cited By ~ 1

Author(s):

N. F. Glasser ◽

S. J. A. Jennings ◽

M. J. Hambrey ◽

B. Hubbard

Keyword(s):

Flow Line ◽

Ice Sheet ◽

Surface Structures ◽

Surface Velocity ◽

Ice Flow ◽

Antarctic Ice Sheet ◽

Ice Surface ◽

Ice Stream ◽

The Antarctic

Abstract. Continent-wide mapping of longitudinal ice-surface structures on the Antarctic Ice Sheet reveals that they originate in the interior of the ice sheet and are arranged in arborescent networks fed by multiple tributaries. Longitudinal ice-surface structures can be traced continuously down-ice for distances of up to 1200 km. They are co-located with fast-flowing glaciers and ice streams that are dominated by basal sliding rates above tens of m yr-1 and are strongly guided by subglacial topography. Longitudinal ice-surface structures dominate regions of converging flow, where ice flow is subject to non-coaxial strain and simple shear. Associating these structures with the AIS' surface velocity field reveals (i) ice residence times of ~ 2500 to 18 500 years, and (ii) undeformed flow-line sets for all major flow units analysed except the Kamb Ice Stream and the Institute and Möller Ice Stream areas. Although it is unclear how long it takes for these features to form and decay, we infer that the major ice-flow and ice-velocity configuration of the ice sheet may have remained largely unchanged for several thousand years, and possibly even since the end of the last glacial cycle. This conclusion has implications for our understanding of the long-term landscape evolution of Antarctica, including large-scale patterns of glacial erosion and deposition.

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Present dynamics and future prognosis of a slowly surging glacier

The Cryosphere ◽

10.5194/tc-5-299-2011 ◽

2011 ◽

Vol 5 (1) ◽

pp. 299-313 ◽

Cited By ~ 49

Author(s):

G. E. Flowers ◽

N. Roux ◽

S. Pimentel ◽

C. G. Schoof

Keyword(s):

Mass Balance ◽

Force Balance ◽

Surface Velocity ◽

Internal Dynamic ◽

Ice Dynamics ◽

Surface Mass ◽

Ice Surface ◽

Glacier Ice ◽

Glacier Flow ◽

Negative Balance

Abstract. Glacier surges are a well-known example of an internal dynamic oscillation whose occurrence is not a direct response to the external climate forcing, but whose character (i.e. period, amplitude, mechanism) may depend on the glacier's environmental or climate setting. We examine the dynamics of a small (∼5 km2) valley glacier in Yukon, Canada, where two previous surges have been photographically documented and an unusually slow surge is currently underway. To characterize the dynamics of the present surge, and to speculate on the future of this glacier, we employ a higher-order flowband model of ice dynamics with a regularized Coulomb-friction sliding law in both diagnostic and prognostic simulations. Diagnostic (force balance) calculations capture the measured ice-surface velocity profile only when non-zero basal water pressures are prescribed over the central region of the glacier, coincident with where evidence of the surge has been identified. This leads to sliding accounting for 50–100% of the total surface motion in this region. Prognostic simulations, where the glacier geometry evolves in response to a prescribed surface mass balance, reveal a significant role played by a bedrock ridge beneath the current equilibrium line of the glacier. Ice thickening occurs above the ridge in our simulations, until the net mass balance reaches sufficiently negative values. We suggest that the bedrock ridge may contribute to the propensity for surges in this glacier by promoting the development of the reservoir area during quiescence, and may permit surges to occur under more negative balance conditions than would otherwise be possible. Collectively, these results corroborate our interpretation of the current glacier flow regime as indicative of a slow surge that has been ongoing for some time, and support a relationship between surge incidence or character and the net mass balance. Our results also highlight the importance of glacier bed topography in controlling ice dynamics, as observed in many other glacier systems.

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Temporal and spatial variability of surface mass balance at Dome Fuji, East Antarctica, by the stake method from 1995 to 2006

Journal of Glaciology ◽

10.3189/002214308784409062 ◽

2008 ◽

Vol 54 (184) ◽

pp. 107-116 ◽

Cited By ~ 60

Author(s):

Takao Kameda ◽

Hideaki Motoyama ◽

Shuji Fujita ◽

Shuhei Takahashi

Keyword(s):

Mass Balance ◽

Ice Core ◽

Snow Accumulation ◽

East Antarctica ◽

Surface Mass Balance ◽

Surface Mass ◽

Frequency Distributions ◽

Temporal And Spatial Variability ◽

The Antarctic ◽

Height Data

AbstractThe surface mass balance (SMB) at Dome Fuji, East Antarctica, was estimated using 36 bamboo stakes (grid of 6 × 6, placed at 20 m intervals) from 1995 to 2006. The heights of the stake tops from the snow surface were measured at 0.5 cm resolution twice monthly in 1995, 1996, 1997 and 2003, and once a year for the rest of the study period. To account for snow settling, the average snow density at the stake base during the measurements was used for converting the stake-height data to SMB. The annual SMB from 1995 to 2006 at Dome Fuji was 27.3 ± 1.5 kg m−2 a−1. This result agrees well with the annual SMB from AD 1260 to 1993 (26.4 kg m−2 a−1) estimated from volcanic signals in the Dome Fuji ice core. Over the period 1995–2006, there were 37 (8.6% of the measurements) negative or zero annual SMB results. Variation in the multi-year averages of annual SMB decreased with the square root of the number of observation years, and 10 years of observations of a single stake allowed the estimation of annual SMB at ±10% accuracy. The frequency distributions of annual and monthly SMB were examined. The findings clarify the complex behavior of the annual and monthly SMB at Dome Fuji, which will be common phenomena in areas of low snow accumulation of the interior of the Antarctic ice sheet.

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Large spatial variation in accumulation rate in Jutulstraumen ice stream, Dronning Maud Land, Antarctica

Annals of Glaciology ◽

10.3189/1998aog27-1-231-238 ◽

1998 ◽

Vol 27 ◽

pp. 231-238 ◽

Cited By ~ 20

Author(s):

Kjetil Melvold ◽

Jon Ove Hagen ◽

Jean Francis Pinglot ◽

Niels Gunuestrup

Keyword(s):

Mass Balance ◽

Accumulation Rate ◽

Austral Summer ◽

Katabatic Winds ◽

Surface Gradient ◽

Ice Stream ◽

Dronning Maud Land ◽

Temporal And Spatial ◽

Accumulation Trend ◽

Local Accumulation

A mass-balance programme was initiated on Jutulstraumen ice stream, western Dronning Maud Land,Antarctica, during the austral summer 1992-93. As a part of the mass-balance programme, accumulation rate was measured along the centre line of Jutulstraumen from the shelf edge up to the plateau at about 2500 m a.s.l. Accumulation distribution obtained from seven shallow firn cores and 48 slake readings is presented. The overall net accumulation trend displays a decreasing accumulation with increasing elevation and distance to coast, but on both the mesoscale and microscale there are significant variations. This is due to complex patterns of precipitation controlled by orography and redistribution by katabatic winds. The local accumulation distribution (few km scale) was found to be dependent on downslope surface gradient (aspect north, northwest), and variations up to 100% were found over distances of less than 3 km. The large variation in accumulation is important when selecting new core sites and for interpretation of temporal and spatial variations in accumulation derived from firn cores.

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Impact of coastal East Antarctic ice rises on surface mass balance: insights from observations and modelling

10.5194/egusphere-egu2020-20370 ◽

2020 ◽

Author(s):

Thore Kausch ◽

Stef Lhermitte ◽

Jan T.M. Lenaerts ◽

Nander Wever ◽

Mana Inoue ◽

...

Keyword(s):

Mass Balance ◽

Wind Erosion ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Windward Side ◽

Leeward Side ◽

Surface Mass Balance ◽

Surface Mass ◽

Local Erosion

About 20% of all snow accumulation in Antarctica occurs on the ice shelfs and ice rises, locations within the ice shelf where the ice is locally grounded on topography. These ice rises largely control the spatial surface mass balance (SMB) distribution by inducing snowfall variability due to orographic uplift and by inducing wind erosion due altering the wind conditions. Moreover these ice rises buttress the ice flow and represent an ideal drilling locations for ice cores.In this study we assess the connection between snowfall variability and wind erosion to provide a better understanding of how ice rises impact SMB variability, how well this is captured in the regional atmospheric climate model RACMO, and the implications of this SMB variability for ice rises as an ice core drilling side. By combining ground penetrating radar profiles from two ice rises in Dronning Maud Land with ice core dating we reconstruct spatial and temporal SMB variations across both ice rises from 1982 to 2017. Subsequently, the observed SMB is compared with output from RACMO, SnowModel to quantify the contribution of the different processes that control the spatial SMB variability across the ice rises. Finally, the observed SMB is compared with Sentinel-1 backscatter data to extrapolate spatial SMB trends over larger areas.Our results show snowfall-driven differences of up to ~ 0.24 m w.e./yr between the windward and the leeward side of both ice rises as well as a local erosion driven minimum at the peak of the ice rises. RACMO captures the snowfall-driven differences, but overestimates their magnitude, whereas the erosion on the peak can be reproduced by SnowModel with RACMO forcing. Observed temporal variability of the average SMBs calculated for 4 time intervals in the 1982-2017 range are low at the peak of the easternmost ice rise (~ 0.03 m w.e./yr), while being three times higher (~ 0.1 m w.e./yr) on the windward side of the ice rise. This implicates that at the peak of the ice rise, higher snowfall, driven by regional processes, such as orographic uplift, is balanced out by local erosion. &#160;Comparison of the observed SMB gradients with Sentinel-1 data finally shows the potential of SAR satellite observations to represent spatial variability in SMB across ice shelves and ice rises.

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Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

The Cryosphere ◽

10.5194/tc-6-1345-2012 ◽

2012 ◽

Vol 6 (6) ◽

pp. 1345-1358 ◽

Cited By ~ 20

Author(s):

D. Verfaillie ◽

M. Fily ◽

E. Le Meur ◽

O. Magand ◽

B. Jourdain ◽

...

Keyword(s):

Mass Balance ◽

Austral Summer ◽

Temporal Variations ◽

Snow Accumulation ◽

Data Depth ◽

East Antarctica ◽

Spatial And Temporal Variability ◽

Coastal Station ◽

International Polar Year ◽

Ground Penetrating

Abstract. The mass balance of ice sheets is an intensively studied topic in the context of global change and sea-level rise. However – particularly in Antarctica – obtaining mass balance estimates remains difficult due to various logistical problems. In the framework of the TASTE-IDEA (Trans-Antarctic Scientific Traverses Expeditions – Ice Divide of East Antarctica) program, an International Polar Year project, continuous ground penetrating radar (GPR) measurements were carried out during a traverse in Adelie Land (East Antarctica) during the 2008–2009 austral summer between the Italian–French Dome C (DC) polar plateau site and French Dumont D'Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability and compare it with historical data and modelling. The focus was on the last 300 yr, from the pre-industrial period to recent times. Beta-radioactivity counting and gamma spectrometry were applied to cores at the LGGE laboratory, providing a depth–age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈ 1730, 1799 and 1941 AD). Preliminary results reveal a gradual increase in accumulation towards the coast (from ≈ 3 cm w.e. a−1 at Dome C to ≈ 17 cm w.e. a−1 at the end of the transect) and previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from previous studies and modelling. Drawing final conclusions on temporal variations is difficult because of the margin of error introduced by density estimation. This study should have various applications, including model validation.

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Synoptic situations causing high precipitation rates on the Antarctic plateau: observations from Kohnen Station, Dronning Maud Land

Antarctic Science ◽

10.1017/s0954102006000320 ◽

2006 ◽

Vol 18 (2) ◽

pp. 279-288 ◽

Cited By ~ 23

Author(s):

Gerit Birnbaum ◽

Ralf Brauner ◽

Hinnerk Ries

Keyword(s):

Large Scale ◽

Ice Core ◽

Mean Value ◽

Cloud Formation ◽

Heavy Snowfall ◽

Greenwich Meridian ◽

Dronning Maud Land ◽

High Precipitation ◽

The Antarctic

Kohnen Station (75°S, 0°E, 2892 m) is one of the two drilling sites of the European Project for Ice Coring in Antarctica. Snow falls at Kohnen only a few times a year with comparatively high precipitation rates of 1 mm to over 5 mm water equivalent per event. These events contribute considerably to the total annual accumulation of which the long-term mean value is 62 mm water equivalent per year. For ice core interpretation, it is important to understand synoptic processes leading to such high precipitation rates. Our investigation is based on visually observed periods of heavy snowfall at Kohnen during summer campaigns since 2001/2002. The corresponding synoptic situations can be grouped into three categories. Category I is where occluding fronts of eastward-moving low pressure systems reach the plateau, a fairly frequent occurrence. Category II is where lows or secondary lows formed east of the Greenwich Meridian move to the west (retrograde movement), and frontal clouds influence the plateau. In Category III, large-scale lifting processes (due to an upper air low west of Kohnen Station) lead to cloud formation over the plateau of Dronning Maud Land.

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