scholarly journals Snowdrift modelling for Vestfonna ice cap, north-eastern Svalbard

2013 ◽  
Vol 7 (1) ◽  
pp. 709-741 ◽  
Author(s):  
T. Sauter ◽  
M. Möller ◽  
R. Finkelnburg ◽  
M. Grabiec ◽  
D. Scherer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Snow Accumulation ◽  
Glacier Mass Balance ◽  
Blowing Snow ◽  
Glacier Surface ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
Ice Cap ◽  
Drifting Snow ◽  
Snow Mass

Abstract. The redistribution of snow by drifting and blowing snow frequently leads to an inhomogeneous snow mass distribution on larger ice caps. Together with the thermodynamic impact of drifting snow sublimation on the lower atmospheric boundary layer, these processes affect the glacier surface mass balance. This study provides a first quantification of snowdrift and sublimation of blowing and drifting snow on Vestfonna ice cap (Svalbard) by using the specifically designed "snow2blow" snowdrift model. The model is forced by atmospheric fields from the Weather Research and Forecasting model and resolves processes on a spatial resolution of 250 m. Comparison with radio-echo soudings and snow-pit measurements show that important local scale processes are resolved by the model and the overall snow accumulation pattern is reproduced. The findings indicate that there is a significant redistribution of snow mass from the interior of the ice cap to the surrounding areas and ice slopes. Drifting snow sublimation of suspended snow is found to be stronger during winter. It is concluded that both processes are strong enough to have a significant impact on glacier mass balance.

scholarly journals Snowdrift modelling for the Vestfonna ice cap, north-eastern Svalbard

2013 ◽  
Vol 7 (4) ◽  
pp. 1287-1301 ◽  
Author(s):  
T. Sauter ◽  
M. Möller ◽  
R. Finkelnburg ◽  
M. Grabiec ◽  
D. Scherer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Snow Accumulation ◽  
Glacier Mass Balance ◽  
Blowing Snow ◽  
Glacier Surface ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
Ice Cap ◽  
Drifting Snow ◽  
Snow Mass

Abstract. The redistribution of snow by drifting and blowing snow frequently leads to an inhomogeneous snow mass distribution on larger ice caps. Together with the thermodynamic impact of drifting snow sublimation on the lower atmospheric boundary layer, these processes affect the glacier surface mass balance. This study provides a first quantification of snowdrift and sublimation of blowing and drifting snow on the Vestfonna ice cap (Svalbard) by using the specifically designed snow2blow snowdrift model. The model is forced by atmospheric fields from the Polar Weather Research and Forecasting model and resolves processes on a spatial resolution of 250 m. The model is applied to the Vestfonna ice cap for the accumulation period 2008/2009. Comparison with radio-echo soundings and snow-pit measurements show that important local-scale processes are resolved by the model and the overall snow accumulation pattern is reproduced. The findings indicate that there is a significant redistribution of snow mass from the interior of the ice cap to the surrounding areas and ice slopes. Drifting snow sublimation of suspended snow is found to be stronger during spring. It is concluded that the redistribution process is strong enough to have a significant impact on glacier mass balance.

scholarly journals Calibrating a surface mass-balance model for Austfonna ice cap, Svalbard

2007 ◽  
Vol 46 ◽  
pp. 241-248 ◽  
Author(s):  
Thomas Vikhamar Schuler ◽  
Even Loe ◽  
Andrea Taurisano ◽  
Trond Eiken ◽  
Jon Ove Hagen ◽  
...  
Keyword(s):  
Mass Balance ◽  
Snow Accumulation ◽  
Balance Model ◽  
Data Series ◽  
Model Parameters ◽  
Surface Mass Balance ◽  
Svalbard Archipelago ◽  
Accumulation Pattern ◽  
Surface Mass ◽  
Ice Cap

AbstractAustfonna (8120km2) is by far the largest ice mass in the Svalbard archipelago. There is considerable uncertainty about its current state of balance and its possible response to climate change. Over the 2004/05 period, we collected continuous meteorological data series from the ice cap, performed mass-balance measurements using a network of stakes distributed across the ice cap and mapped the distribution of snow accumulation using ground-penetrating radar along several profile lines. These data are used to drive and test a model of the surface mass balance. The spatial accumulation pattern was derived from the snow depth profiles using regression techniques, and ablation was calculated using a temperature-index approach. Model parameters were calibrated using the available field data. Parameter calibration was complicated by the fact that different parameter combinations yield equally acceptable matches to the stake data while the resulting calculated net mass balance differs considerably. Testing model results against multiple criteria is an efficient method to cope with non-uniqueness. In doing so, a range of different data and observations was compared to several different aspects of the model results. We find a systematic underestimation of net balance for parameter combinations that predict observed ice ablation, which suggests that refreezing processes play an important role. To represent these effects in the model, a simple PMAX approach was included in its formulation. Used as a diagnostic tool, the model suggests that the surface mass balance for the period 29 April 2004 to 23 April 2005 was negative (–318mmw.e.).

scholarly journals The importance of wind-blown snow redistribution to snow accumulation on Bellingshausen Sea ice

2011 ◽  
Vol 52 (57) ◽  
pp. 271-278 ◽  
Author(s):  
Katherine C. Leonard ◽  
Ted Maksym
Keyword(s):  
Sea Ice ◽  
Mass Balance ◽  
Snow Accumulation ◽  
Blowing Snow ◽  
Wind Speeds ◽  
Antarctic Sea Ice ◽  
Drifting Snow ◽  
Bellingshausen Sea ◽  
Ice Mass Balance ◽  
High Winds

AbstractSnow distribution is a dominating factor in sea-ice mass balance in the Bellingshausen Sea, Antarctica, through its roles in insulating the ice and contributing to snow-ice production. the wind has long been qualitatively recognized to influence the distribution of snow accumulation on sea ice, but the relative importance of drifting and blowing snow has not been quantified over Antarctic sea ice prior to this study. the presence and magnitude of drifting snow were monitored continuously along with wind speeds at two sites on an ice floe in the Bellingshausen Sea during the October 2007 Sea Ice Mass Balance in the Antarctic (SIMBA) experiment. Contemporaneous precipitation measurements collected on board the RVIB Nathaniel B. Palmer and accumulation measurements by automated ice mass-balance buoys (IMBs) allow us to document the proportion of snowfall that accumulated on level ice surfaces in the presence of high winds and blowing-snow conditions. Accumulation on the sea ice during the experiment averaged <0.01 m w.e. at both IMB sites, during a period when European Centre for Medium-Range Weather Forecasts analyses predicted >0.03 m w.e. of precipitation on the ice floe. Accumulation changes on the ice floe were clearly associated with drifting snow and high winds. Drifting-snow transport during the SIMBA experiment was supply-limited. Using these results to inform a preliminary study using a blowing-snow model, we show that over the entire Southern Ocean approximately half of the precipitation over sea ice could be lost to leads.

scholarly journals Estimation of the Antarctic surface mass balance using MAR (1979–2015) and identification of dominant processes

2018 ◽  
Author(s):  
Cécile Agosta ◽  
Charles Amory ◽  
Christoph Kittel ◽  
Anais Orsi ◽  
Vincent Favier ◽  
...  
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Regional Climate ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Surface Mass Balance ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Drifting Snow ◽  
The Antarctic

Abstract. The Antarctic ice sheet mass balance is a major component of the sea level budget and results from the difference of two fluxes of a similar magnitude: ice flow discharging in the ocean and net snow accumulation on the ice sheet surface, i.e. the surface mass balance (SMB). Separately modelling ice dynamics and surface mass balance is the only way to project future trends. In addition, mass balance studies frequently use regional climate models (RCMs) outputs as an alternative to observed fields because SMB observations are particularly scarce on the ice sheet. Here we evaluate new simulations of the polar RCM MAR forced by three reanalyses, ERA-Interim, JRA-55 and MERRA2, for the period 1979–2015, and we compare our results to the last outputs of the RCM RACMO2 forced by ERA-Interim. We show that MAR and RACMO2 perform similarly well in simulating coast to plateau SMB gradients, and we find no significant differences in their simulated SMB when integrated over the ice sheet or its major basins. More importantly, we outline and quantify missing processes in both RCMs. Along stake transects, we show that both models accumulate too much snow on crests, and not enough snow in valleys, as a result of erosion-deposition processes not included in MAR, where the drifting snow module has been switched off, and probably underestimated in RACMO2 by a factor of three. As a consequence, the amount of drifting snow sublimating in the atmospheric boundary layer remains a potentially large mass sink needed to be better constrained. Moreover, MAR generally simulates larger SMB and snowfall amounts than RACMO2 inland, whereas snowfall rates are significantly lower in MAR than in RACMO2 at the ice sheet margins. This divergent behaviour at the margins results from differences in model parameterisations, as MAR explicitly advects precipitating particles through the atmospheric layers and sublimates snowflakes in the undersaturated katabatic layer, whereas in RACMO2 precipitation is added to the surface without advection through the atmosphere. Consequently, we corroborate a recent study concluding that sublimation of precipitation in the low-level atmospheric layers is a significant mass sink for the Antarctic SMB, as it may represent ∼ 240 ± 25 Gt yr-1 of difference in snowfall between RACMO2 and MAR for the period 1979–2015, which is 10 % of the simulated snowfall loaded on the ice sheet and more than twice the surface snow sublimation as currently simulated by MAR.

scholarly journals Micrometeorological conditions and surface mass and energy fluxes on Lewis Glacier, Mt Kenya, in relation to other tropical glaciers

2013 ◽  
Vol 7 (4) ◽  
pp. 1205-1225 ◽  
Author(s):  
L. I. Nicholson ◽  
R. Prinz ◽  
T. Mölg ◽  
G. Kaser
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Cloud Cover ◽  
Meteorological Data ◽  
Snow Accumulation ◽  
Energy Fluxes ◽  
Glacier Surface ◽  
Monte Carlo Optimization ◽  
Surface Mass ◽  
Tropical Glaciers

Abstract. The Lewis Glacier on Mt Kenya is one of the best-studied tropical glaciers, but full understanding of the interaction of the glacier mass balance and its climatic drivers has been hampered by a lack of long-term meteorological data. Here we present 2.5 yr of meteorological data collected from the glacier surface from October 2009 to February 2012. The location of measurements is in the upper portion of Lewis Glacier, but this location experiences negative annual mass balance, and the conditions are comparable to those experienced in the lower ablation zones of South American glaciers in the inner tropics. In the context of other glaciated mountains of equatorial East Africa, the summit zone of Mt Kenya shows strong diurnal cycles of convective cloud development as opposed to the Rwenzoris, where cloud cover persists throughout the diurnal cycle, and Kilimanjaro, where clear skies prevail. Surface energy fluxes were calculated for the meteorological station site using a physical mass- and energy-balance model driven by measured meteorological data and additional input parameters that were determined by Monte Carlo optimization. Sublimation rate was lower than those reported on other tropical glaciers, and melt rate was high throughout the year, with the glacier surface reaching the melting point on an almost daily basis. Surface mass balance is influenced by both solid precipitation and air temperature, with radiation providing the greatest net source of energy to the surface. Cloud cover typically reduces the net radiation balance compared to clear-sky conditions, and thus the frequent formation of convective clouds over the summit of Mt Kenya and the associated higher rate of snow accumulation are important in limiting the rate of mass loss from the glacier surface. The analyses shown here form the basis for future glacier-wide mass and energy balance modeling to determine the climate proxy offered by the glaciers of Mt Kenya.

scholarly journals Influence of precipitation seasonality on glacier mass balance and its sensitivity to climate change

2008 ◽  
Vol 48 ◽  
pp. 88-92 ◽  
Author(s):  
Koji Fujita
Keyword(s):  
Mass Balance ◽  
Surface Albedo ◽  
Summer Precipitation ◽  
Arid Environment ◽  
Climatic Conditions ◽  
Snow Accumulation ◽  
Annual Precipitation ◽  
Glacier Mass Balance ◽  
Accumulation Pattern ◽  
Precipitation Seasonality

AbstractNumerical calculations are described, aimed at evaluating the influence of precipitation seasonality (summer and winter) on glacier mass balance. First, equilibrium-line altitudes (ELAs) are modeled using idealized meteorological variables. Modeled climatic conditions (summer mean temperature and annual precipitation) at the ELA of glaciers located within a winter accumulation pattern confirm the observational results of earlier studies. However, the ELA of glaciers located within a summer accumulation climate pattern locates in a colder environment than that of glaciers located within a winter accumulation climate pattern. This difference is mainly due to the annual snow accumulation and the surface albedo. A warming test (+1K) reveals higher sensitivities for the glaciers located within a summer accumulation pattern than for the glaciers located within a winter accumulation pattern. In a humid environment, a significant decrease in snow accumulation on the glaciers located within a summer accumulation pattern directly causes higher sensitivities. In an arid environment, on the other hand, the decreased summer snow induces accelerated melting by lowering the surface albedo and thus increasing absorption of solar radiation on the glaciers located within a summer accumulation pattern. Both influences are due to significant differences in summer precipitation. This study shows the importance of precipitation seasonality on the climatic sensitivity of glacier mass balance, which in previous studies has been linked only with annual precipitation.

scholarly journals Micrometeorological conditions and surface mass and energy fluxes on Lewis glacier, Mt Kenya, in relation to other tropical glaciers

2012 ◽  
Vol 6 (6) ◽  
pp. 5181-5224 ◽  
Author(s):  
L. Nicholson ◽  
R. Prinz ◽  
T. Mölg ◽  
G. Kaser
Keyword(s):  
Energy Balance ◽  
Mass Balance ◽  
Cloud Cover ◽  
Meteorological Data ◽  
Snow Accumulation ◽  
Energy Fluxes ◽  
Glacier Surface ◽  
Monte Carlo Optimization ◽  
Surface Mass ◽  
Tropical Glaciers

Abstract. The Lewis Glacier on Mt Kenya is one of the best-studied tropical glaciers, but full understanding of the interaction of the glacier mass balance and climate forcing has been hampered by a lack of long term meteorological data. Here we present 2.5 yr of meteorological data collected from the glacier surface from October 2009–February 2012, which indicate that mean meteorological conditions in the upper zone of Lewis Glacier are comparable to those experienced in the ablation zones of South American tropical glaciers. In the context of other glaciated mountains of equatorial east Africa, the summit zone of Mt Kenya shows strong diurnal cycles of convective cloud development as opposed to the Rwenzoris where cloud cover persists throughout the diurnal cycle and Kilimanjaro where clear skies prevail. Surface energy fluxes were calculated for the meteorological station site using a physical mass- and energy-balance model driven by hourly measured meteorological data and additional input parameters that were determined by Monte Carlo optimization. Sublimation rate was lower than those reported on other tropical glaciers and melt rate was high throughout the year, with the glacier surface reaching the melting point on an almost daily basis. Surface mass balance is influenced by both solid precipitation and air temperature, with radiation providing the greatest net source of energy to the surface. Cloud cover typically reduces the net radiation balance compared to clear sky conditions, and thus the more frequent formation of convective clouds over the summit of Mt Kenya, and the associated higher rate of snow accumulation are important in limiting the rate of mass loss from the glacier surface. The analyses shown here are the basis for glacier-wide mass and energy balance modeling to determine the climate proxy offered by the glaciers of Mt Kenya.

scholarly journals The Influence of Air Temperature Inversions on Snowmelt and Glacier Mass Balance Simulations, Ammassalik Island, Southeast Greenland

2010 ◽  
Vol 49 (1) ◽  
pp. 47-67 ◽  
Author(s):  
Sebastian H. Mernild ◽  
Glen E. Liston
Keyword(s):  
Mass Balance ◽  
Air Temperature ◽  
Inversion Layer ◽  
Snow Accumulation ◽  
Glacier Mass Balance ◽  
Equilibrium Line Altitude ◽  
Surface Mass ◽  
Simulation Domain ◽  
Glacier Ice ◽  
Temperature Inversions

Abstract In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow evolution modeling system (SnowModel) was used to simulate 8 yr (1998/99–2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution submodel used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates because of the potential of inversion breakup. Field observations showed inversions to extend from sea level to approximately 300 m MSL, and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower-elevation areas and cooler higher-elevation areas than without inversion routines because of the use of cold sea-breeze-based temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1–3 weeks later snowmelt in the higher-elevation areas of the simulation domain. Averaged mean annual modeled surface mass balance for all glaciers (mainly located above the inversion layer) was −720 ± 620 mm w.eq. yr−1 (w.eq. is water equivalent) for inversion simulations, and −880 ± 620 mm w.eq. yr−1 without the inversion routines, a difference of 160 mm w.eq. yr−1. The annual glacier loss for the two simulations was 50.7 × 106 and 64.4 × 106 m3 yr−1 for all glaciers—a difference of ∼21%. The average equilibrium line altitude (ELA) for all glaciers in the simulation domain was located at 875 and 900 m MSL for simulations with or without inversion routines, respectively.

Climatic Interpretation of Alpine Snowline Variations on Millennial Time Scales

1994 ◽  
Vol 41 (2) ◽  
pp. 154-159 ◽  
Author(s):  
Geoffrey O. Seltzer
Keyword(s):  
Mass Balance ◽  
Time Scales ◽  
Snow Accumulation ◽  
Lapse Rate ◽  
Glacier Mass Balance ◽  
Glacier Surface ◽  
Proxy Records ◽  
Alpine Glaciers ◽  
Number Of Factors ◽  
Mass Balance Approach

AbstractThe depression of snowlines, or equilibrium-line altitudes, of alpine glaciers is often used by glacial geologists to infer variations in mass balance. The climatic interpretation of snowline depression, however, is complicated by the number of factors that control glacier mass balance. The simple lapse-rate method of temperature interpretation ignores the effects of changes in radiation and snow accumulation. The statistical approach to temperature interpretation, which regresses precipitation and temperature against snowline altitude, neglects the effect of radiation. The most comprehensive approach for the climatic interpretation of snowline depression couples the heat and mass balances of a glacier surface. A sensitivity analysis that utilizes the coupled heat- and mass-balance approach indicates that the ∼1000-m variation in snowline of alpine glaciers on glacial-to-interglacial time scales could be a result of significant changes in temperature, and to a lesser extent changes in insolation. Snowline variations are sensitive only to relatively large changes in annual accumulation, which should also be evident in other proxy records of moisture change. The approaches outlined here provide glacial geologists with a summary of how various climatic forcings associated with glaciation may be quantified from snowline data.

Detailed simulations of snow properties and accumulation across the Antarctic Ice Sheet

2020 ◽  
Author(s):  
Jan Lenaerts ◽  
Eric Keenan ◽  
Nander Wever ◽  
Marissa Dattler ◽  
Carleen Reijmer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Small Scale ◽  
Blowing Snow ◽  
Antarctic Ice Sheet ◽  
Near Surface ◽  
Surface Mass ◽  
Order Of Magnitude ◽  
Snow Model

&lt;p&gt;Surface mass balance (SMB) represents a large uncertainty in characterizing Antarctic Ice Sheet (AIS) mass balance. Atmospheric reanalysis products, which are commonly used for AIS SMB studies, do not include small-scale snow redistribution processes even though these can be of the same order of magnitude as snow accumulation in many parts of the AIS. Therefore, a proper representation of these processes is critical to interpret local SMB and firn observations, such as from ICESat-2 repeat altimetry. In this study, we use a detailed, multi-layer snow model (SNOWPACK) forced by a global atmospheric reanalysis (MERRA-2). Firstly, we show that a new accumulation scheme, designed to better represent wind-driven snow compaction in SNOWPACK, substantially reduces simulated biases in near-surface snow density at 131 locations across the AIS. Next, we employ a distributed version of SNOWPACK to two regions on the AIS, and compare the simulation output to airborne radar and in-situ observations of SMB. Our results demonstrate that SNOWPACK can capture the timing of blowing snow events, snow erosion events, as well as observed kilometer-scale spatial SMB variability. This study illustrates the importance of using high-resolution SMB models when converting surface height (volume) observations to mass changes.&lt;/p&gt;

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