scholarly journals Climate variables along a traverse line in Dronning Maud Land, East Antarctica

1999 ◽  
Vol 45 (150) ◽  
pp. 295-302 ◽  
Author(s):  
Michiel R. van den Broeke ◽  
Jan-Gunnar Winther ◽  
Elisabeth Isaksson ◽  
Jean Francis Pinglot ◽  
Lars Karlöf ◽  
...  
Keyword(s):  
Potential Temperature ◽  
Ice Sheet ◽  
High Elevation ◽  
Cold Climate ◽  
East Antarctica ◽  
Katabatic Wind ◽  
Near Surface ◽  
Surface Mass ◽  
Drifting Snow ◽  
Dronning Maud Land

AbstractTemperature, density and accumulation data were obtained from shallow firn cores, drilled during an overland traverse through a previously unknown part of Dronning Maud Land, East Antarctica. The traverse area is characterised by high mountains that obstruct the ice flow, resulting in a sudden transition from the polar plateau to the coastal region. The spatial variations of potential temperature, near-surface firn density and accumulation suggest that katabatic winds are active in this region. Proxy wind data derived from firn-density profiles confirm that annual mean wind speed is strongly related to the magnitude of the surface slope. The high elevation of the ice sheet south of the mountains makes for a dry, cold climate, in which mass loss owing to sublimation is small and erosion of snow by the wind has a potentially large impact on the surface mass balance. A simple katabatic-wind model is used to explain the variations of accumulation along the traverse line in terms of divergence/convergence of the local transport of drifting snow. The resulting wind- and snowdrift patterns are closely connected to the topography of the ice sheet: ridges are especially sensitive to erosion, while ice streams and other depressions act as collectors of drifting snow.

scholarly journals Climate variables along a traverse line in Dronning Maud Land, East Antarctica

1999 ◽  
Vol 45 (150) ◽  
pp. 295-302 ◽  
Author(s):  
Michiel R. van den Broeke ◽  
Jan-Gunnar Winther ◽  
Elisabeth Isaksson ◽  
Jean Francis Pinglot ◽  
Lars Karlöf ◽  
...  
Keyword(s):  
Potential Temperature ◽  
Ice Sheet ◽  
High Elevation ◽  
Cold Climate ◽  
East Antarctica ◽  
Katabatic Wind ◽  
Near Surface ◽  
Surface Mass ◽  
Drifting Snow ◽  
Dronning Maud Land

AbstractTemperature, density and accumulation data were obtained from shallow firn cores, drilled during an overland traverse through a previously unknown part of Dronning Maud Land, East Antarctica. The traverse area is characterised by high mountains that obstruct the ice flow, resulting in a sudden transition from the polar plateau to the coastal region. The spatial variations of potential temperature, near-surface firn density and accumulation suggest that katabatic winds are active in this region. Proxy wind data derived from firn-density profiles confirm that annual mean wind speed is strongly related to the magnitude of the surface slope. The high elevation of the ice sheet south of the mountains makes for a dry, cold climate, in which mass loss owing to sublimation is small and erosion of snow by the wind has a potentially large impact on the surface mass balance. A simple katabatic-wind model is used to explain the variations of accumulation along the traverse line in terms of divergence/convergence of the local transport of drifting snow. The resulting wind- and snowdrift patterns are closely connected to the topography of the ice sheet: ridges are especially sensitive to erosion, while ice streams and other depressions act as collectors of drifting snow.

scholarly journals Brief communication: Rare ambient saturation during drifting snow occurrences at a coastal location of East Antarctica

2019 ◽  
Vol 13 (12) ◽  
pp. 3405-3412 ◽  
Author(s):  
Charles Amory ◽  
Christoph Kittel
Keyword(s):  
Relative Humidity ◽  
Meteorological Data ◽  
Ice Sheet ◽  
Ambient Air ◽  
East Antarctica ◽  
Strong Increase ◽  
Katabatic Wind ◽  
Strong Wind ◽  
Near Surface ◽  
Drifting Snow

Abstract. Sublimation of snow particles during transport has been recognized as an important ablation process on the Antarctic ice sheet. The resulting increase in moisture content and cooling of the ambient air are thermodynamic negative feedbacks that both contribute to increase the relative humidity of the air, inhibiting further sublimation when saturation is reached. This self-limiting effect and the associated development of saturated near-surface air layers in drifting snow conditions have mainly been described through modelling studies and a few field observations. A set of meteorological data, including drifting snow mass fluxes and vertical profiles of relative humidity, collected at site D17 in coastal Adélie Land (East Antarctica) during 2013 is used to study the relationship between saturation of the near-surface atmosphere and the occurrence of drifting snow in a katabatic wind region that is among the most prone to snow transport by wind. Atmospheric moistening by the sublimation of the windborne snow particles generally results in a strong increase in relative humidity with the magnitude of drifting snow and a decrease in its vertical gradient, suggesting that windborne-snow sublimation can be an important contributor to the local near-surface moisture budget. Despite a high incidence of drifting snow at the measurement location (60.1 % of the time), saturation, when attained, is however most often limited to a thin air layer below 1 m above ground. The development of a near-surface saturated air layer up to the highest measurement level of 5.5 m is observed in only 8.2 % of the drifting snow occurrences or 6.3 % of the time and mainly occurs in strong wind speed and drift conditions. This relatively rare occurrence of ambient saturation is explained by the likely existence of moisture-removal mechanisms inherent to the katabatic and turbulent nature of the boundary-layer flow that weaken the negative feedback of windborne-snow sublimation. Such mechanisms, potentially quite active in katabatic-generated windborne-snow layers all over Antarctica, may be very important in understanding the surface mass and atmospheric moisture budgets of the ice sheet by enhancing windborne-snow sublimation.

scholarly journals How does the ice sheet surface mass balance relate to snowfall? Insights from a ground-based precipitation radar in East Antarctica

2017 ◽  
Author(s):  
Niels Souverijns ◽  
Alexandra Gossart ◽  
Irina V. Gorodetskaya ◽  
Stef Lhermitte ◽  
Alexander Mangold ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Local Scale ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Clear Understanding ◽  
Surface Mass ◽  
Drifting Snow ◽  
Dronning Maud Land ◽  
Good Proxy

Abstract. Local surface mass balance (SMB) measurements are crucial for understanding changes in the total mass of the Antarctic Ice Sheet, including its contribution to sea level rise. Despite continuous attempts to decipher mechanisms controlling the local SMB, a clear understanding of the separate components is still lacking, while snowfall measurements are almost absent. In this study, the different terms are quantified at the Princess Elisabeth (PE) station in Dronning Maud Land, East Antarctica. Furthermore, the relation between snowfall and accumulation at the surface is investigated. To achieve this, a unique collocated set of remote sensing instrumentation (Micro Rain Radar, ceilometer, Automatic Weather Station, among others) was established operating for an unprecedented time period of 37 months. Snowfall originates mainly from moist and warm air advected from lower latitudes associated with cyclone activity. However, snowfall events are much more common than accumulation events. During 38 % of the snowfall cases observed, the freshly-fallen snow is ablated by the wind during the course of the event. Generally, snow storms of longer duration have a higher chance to attain for accumulation at the local scale, while shorter events usually attain for ablation (on average 17 and 12 hours respectively). As such, SMB records cannot be considered a good proxy for snowfall at the local scale. Accumulation and ablation also occur during non-snowfall conditions. A large part of the accumulation at the station takes place when preceding snowfall events were occurring in upstream coastal areas. This fresh snow is easily picked up and transported in shallow drifting snow layers to more inland locations, even when wind speed is relatively low (

scholarly journals Brief communication: Rare ambient saturation during drifting snow occurrences in coastal East Antarctica

2019 ◽  
Author(s):  
Charles Amory ◽  
Christoph Kittel
Keyword(s):  
Relative Humidity ◽  
Meteorological Data ◽  
Ice Sheet ◽  
Ambient Air ◽  
East Antarctica ◽  
Strong Increase ◽  
Katabatic Wind ◽  
Strong Wind ◽  
Near Surface ◽  
Drifting Snow

Abstract. Sublimation of snow particles during transport has been recognized as the main ablation process on the Antarctic ice sheet. The resulting increase in moisture content and cooling of the ambient air are thermodynamic negative feedbacks that both contribute to increase the relative humidity of the air, inhibiting further sublimation when saturation is reached. This self-limiting effect and the associated development of saturated near-surface air layers in drifting snow conditions have been mainly described through modelling studies and few field observations. A set of meteorological data including drifting snow mass fluxes and vertical profiles of relative humidity collected at site D17 in coastal Adelie Land (East Antarctica) during year 2013 is used to study the relationship between saturation of the near-surface atmosphere and the occurrence of drifting snow in a katabatic wind region among the most prone to snow transport by wind. Atmospheric moistening by the sublimation of the windborne snow particles generally results in a strong increase in relative humidity with the magnitude of drifting snow and a decrease of its vertical gradient, suggesting that windborne-snow sublimation can be an important contributor to the local near-surface moisture budget. Despite a high incidence of drifting snow at the measurement location (61.3 % of the time), saturation, when attained, is however most often limited to a thin air layer below 2 meters above ground. The development of a near-surface saturated air layer up to the highest measurement level of 5.5 m is observed in only 9.6 % of the drifting snow occurrences or 5.9 % of the time and mainly occurs in strong wind speed and drift conditions. This rare occurrence of ambient saturation is explained by the likely existence of moisture-removal mechanisms inherent to the katabatic nature of the boundary-layer flow that weaken the negative feedback of windborne-snow sublimation. Such mechanisms, potentially quite active in katabatic-generated windborne-snow layers all over Antarctica may be very important in understanding the surface mass and atmospheric moisture budgets of the ice sheet by enhancing windborne-snow sublimation.

scholarly journals Surface and snowdrift sublimation at Princess Elisabeth station, East Antarctica

2012 ◽  
Vol 6 (4) ◽  
pp. 841-857 ◽  
Author(s):  
W. Thiery ◽  
I. V. Gorodetskaya ◽  
R. Bintanja ◽  
N. P. M. Van Lipzig ◽  
M. R. Van den Broeke ◽  
...  
Keyword(s):  
Mass Balance ◽  
East Antarctica ◽  
Lower Probability ◽  
Research Station ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Drifting Snow ◽  
Dronning Maud Land ◽  
Meteorological Observations ◽  
Strong Winds

Abstract. In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS) near the Belgian research station Princess Elisabeth in Dronning Maud Land, East-Antarctica, are used to study surface and snowdrift sublimation and to assess their impacts on both the surface mass balance and the surface energy balance during 2009 and 2010. Comparison to three other AWSs in Dronning Maud Land with 11 to 13 yr of observations shows that sublimation has a significant influence on the surface mass balance at katabatic locations by removing 10–23% of their total precipitation, but at the same time reveals anomalously low surface and snowdrift sublimation rates at Princess Elisabeth (17 mm w.e. yr−1 compared to 42 mm w.e. yr−1 at Svea Cross and 52 mm w.e. yr−1 at Wasa/Aboa). This anomaly is attributed to local topography, which shields the station from strong katabatic influence, and, therefore, on the one hand allows for a strong surface inversion to persist throughout most of the year and on the other hand causes a lower probability of occurrence of intermediately strong winds. This wind speed class turns out to contribute most to the total snowdrift sublimation mass flux, given its ability to lift a high number of particles while still allowing for considerable undersaturation.

scholarly journals How does the ice sheet surface mass balance relate to snowfall? Insights from a ground-based precipitation radar in East Antarctica

2018 ◽  
Vol 12 (6) ◽  
pp. 1987-2003 ◽  
Author(s):  
Niels Souverijns ◽  
Alexandra Gossart ◽  
Irina V. Gorodetskaya ◽  
Stef Lhermitte ◽  
Alexander Mangold ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Clear Understanding ◽  
Surface Mass ◽  
Wind Speeds ◽  
Drifting Snow ◽  
Set Up ◽  
The Antarctic

Abstract. Local surface mass balance (SMB) measurements are crucial for understanding changes in the total mass of the Antarctic Ice Sheet, including its contribution to sea level rise. Despite continuous attempts to decipher mechanisms controlling the local and regional SMB, a clear understanding of the separate components is still lacking, while snowfall measurements are almost absent. In this study, the different terms of the SMB are quantified at the Princess Elisabeth (PE) station in Dronning Maud Land, East Antarctica. Furthermore, the relationship between snowfall and accumulation at the surface is investigated. To achieve this, a unique collocated set of ground-based and in situ remote sensing instrumentation (Micro Rain Radar, ceilometer, automatic weather station, among others) was set up and operated for a time period of 37 months. Snowfall originates mainly from moist and warm air advected from lower latitudes associated with cyclone activity. However, snowfall events are not always associated with accumulation. During 38 % of the observed snowfall cases, the freshly fallen snow is ablated by the wind during the course of the event. Generally, snow storms of longer duration and larger spatial extent have a higher chance of resulting in accumulation on a local scale, while shorter events usually result in ablation (on average 17 and 12 h respectively). A large part of the accumulation at the station takes place when preceding snowfall events were occurring in synoptic upstream areas. This fresh snow is easily picked up and transported in shallow drifting snow layers over tens of kilometres, even when wind speeds are relatively low (< 7 ms−1). Ablation events are mainly related to katabatic winds originating from the Antarctic plateau and the mountain ranges in the south. These dry winds are able to remove snow and lead to a decrease in the local SMB. This work highlights that the local SMB is strongly influenced by synoptic upstream conditions.

scholarly journals Surface and snowdrift sublimation at Princess Elisabeth station, East Antarctica

2012 ◽  
Vol 6 (2) ◽  
pp. 1491-1530
Author(s):  
W. Thiery ◽  
I. V. Gorodetskaya ◽  
R. Bintanja ◽  
N. P. M. van Lipzig ◽  
M. R. van den Broeke ◽  
...  
Keyword(s):  
Mass Balance ◽  
East Antarctica ◽  
Lower Probability ◽  
Research Station ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Drifting Snow ◽  
Dronning Maud Land ◽  
Meteorological Observations ◽  
Strong Winds

Abstract. In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS) near the Belgian research station Princess Elisabeth in Dronning Maud Land, East-Antarctica, are used to study surface and snowdrift sublimation and to assess their impacts on both the surface mass balance and the surface energy balance. Comparison to three other AWSs in Dronning Maud Land shows that sublimation has a significant influence on the surface mass balance at katabatic locations by removing 10–23 % of their total precipitation, but at the same time reveals anomalously low surface and snowdrift sublimation rates at Princess Elisabeth (18 mm w.e. yr–1 compared to 42 mm w.e. yr–1 at Svea Cross and 52 mm w.e. yr–1 at Wasa/Aboa). This anomaly is attributed to local topography, which shields the station from strong katabatic influence, and therefore on the one hand allows for a strong surface inversion to persist throughout most of the year and on the other hand causes a lower probability of occurrence of intermediately strong winds. These wind speed classes turn out to contribute most to the total snowdrift sublimation mass flux, given their ability to lift a high number of particles while still allowing for considerable undersaturation.

scholarly journals The interaction of katabatic winds and the formation of blue-ice areas in East Antarctica

1995 ◽  
Vol 41 (138) ◽  
pp. 395-407 ◽  
Author(s):  
Michiel Van Den Broeke ◽  
Richard Bintanja
Keyword(s):  
Wind Speed ◽  
Drainage Basin ◽  
Surface Wind ◽  
Magnitude Estimate ◽  
East Antarctica ◽  
Katabatic Wind ◽  
Diagnostic Model ◽  
Drifting Snow ◽  
Dronning Maud Land ◽  
Inversion Strength

AbstractBlue-ice areas (BIAs) are an extreme example of a local mass-balance gradient and are furthermore reasonably stable in time and space owing to local feed-back mechanisms. A meteorological experiment, performed in and around a blue-ice area in Dronning Maud Land. East Antarctica, showed that during drifting-snow conditions surface wind speed over the blue ice behind the mountain barrier is equal to that away from the mountains, when corrected for surface roughness and stability. This implies that use of diagnostic katabatic wind models to estimate divergence of drifting snow can be extended to the situation where nunataks are involved in preventing the drifting snow from passing, which is the case for most BIAs. A diagnostic model is tested for a two-dimensional profile in Terre Adélie. after which it is applied to entire East Antarctica. The present order-of-magnitude estimate shows that areas sensitive to blue-ice formation appear where precipitation is low and mean annual wind speed is high, i.e. in Dronning Maud Land and the drainage basin of Lambert Glacier. The results appeared to be especially sensitive to a change in inversion strength: a decrease in inversion strength weakens the katabatic flow, and thus the amount of snowdrift transport, reducing the area where BIAs can develop.

scholarly journals Performance of MAR (v3.11) in simulating the drifting-snow climate and surface mass balance of Adélie Land, East Antarctica

2021 ◽  
Vol 14 (6) ◽  
pp. 3487-3510
Author(s):  
Charles Amory ◽  
Christoph Kittel ◽  
Louis Le Toumelin ◽  
Cécile Agosta ◽  
Alison Delhasse ◽  
...  
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Climate Model ◽  
Comprehensive Evaluation ◽  
Regional Climate ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Near Surface ◽  
Surface Mass ◽  
Drifting Snow

Abstract. Drifting snow, or the wind-driven transport of snow particles originating from clouds and the surface below and above 2 m above ground and their concurrent sublimation, is a poorly documented process on the Antarctic ice sheet, which is inherently lacking in most climate models. Since drifting snow mostly results from erosion of surface particles, a comprehensive evaluation of this process in climate models requires a concurrent assessment of simulated drifting-snow transport and the surface mass balance (SMB). In this paper a new version of the drifting-snow scheme currently embedded in the regional climate model MAR (v3.11) is extensively described. Several important modifications relative to previous version have been implemented and include notably a parameterization for drifting-snow compaction of the uppermost snowpack layer, differentiated snow density at deposition between precipitation and drifting snow, and a rewrite of the threshold friction velocity above which snow erosion initiates. Model results at high resolution (10 km) over Adélie Land, East Antarctica, for the period 2004–2018 are presented and evaluated against available near-surface meteorological observations at half-hourly resolution and annual SMB estimates. The evaluation demonstrates that MAR resolves the local drifting-snow frequency and transport up to the scale of the drifting-snow event and captures the resulting observed climate and SMB variability, suggesting that this model version can be used for continent-wide applications.

scholarly journals Changes in the firn structure of the Greenland Ice Sheet caused by recent warming

2015 ◽  
Vol 9 (1) ◽  
pp. 541-565 ◽  
Author(s):  
S. de la Peña ◽  
I. M. Howat ◽  
P. W. Nienow ◽  
M. R. van den Broeke ◽  
E. Mosley-Thompson ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Gain ◽  
High Elevation ◽  
Near Surface ◽  
Surface Mass ◽  
Ice Sheet Mass Balance ◽  
Ice Content ◽  
Percolation Zone

Abstract. Atmospheric warming over the Greenland Ice Sheet during the last two decades has increased the amount of surface meltwater production, resulting in the migration of melt and percolation regimes to higher altitudes and an increase in the amount of solid ice from refrozen meltwater found in the firn above the equilibrium line. Here we present observations of near-surface (0–20 m) firn conditions in western Greenland obtained from campaigns between 1998 and 2014. We find a sharp increase in firn ice content in the form of thick widespread layers in the percolation zone, which decreases the capacity of the firn to store meltwater. The estimated total annual ice content retained in the firn in areas with positive surface mass balance west of the ice divide in Greenland reached a maximum of 74 ± 25 Gt in 2012, compared to the 1958–1999 average of 13 ± 2 Gt, while the percolation zone area more than doubled between 2003 and 2012. Increased melt and column densification resulted in surface lowering averaging −0.80 ± 0.39 m yr−1 between 1800 and 2800 m in the accumulation zone of western Greenland. Since 2007, annual melt and refreezing rates in the percolation zone at elevations below 2100 m surpass the annual snowfall from the previous year, implying that mass gain in the region is now in the form of refrozen meltwater. If current melt trends over high elevation regions continue, subsequent changes in firn structure will have implications for the hydrology of the ice sheet and related abrupt seasonal densification could become increasingly significant for altimetry-derived ice sheet mass balance estimates.

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