scholarly journals Drifting snow statistics from multiple-year autonomous measurements in Adelie Land, eastern Antarctica

2019 ◽  
Author(s):  
Charles Amory
Keyword(s):  
Temporal Frequency ◽  
Field Measurements ◽  
Near Surface ◽  
Continental Scale ◽  
Drifting Snow ◽  
Single Location ◽  
Antarctic Continent ◽  
Short Time ◽  
The Antarctic ◽  
Snow Transport

Abstract. Drifting snow is a widespread feature over the Antarctic ice sheet whose climatological and hydrological significances at the continental scale have been consequently investigated through modelling and satellite approaches. While field measurements are needed to evaluate and interpret model and punctual satellite products, most drifting snow observation campaigns in Antarctica involved data collected at a single location and over short time periods. With the aim of acquiring new data relevant to the observations and modelling of drifting snow in Antarctic conditions, two remote locations in coastal Adelie Land (East Antarctica) 100 km apart were instrumented in January 2010 with meteorological and second-generation IAV Engineering acoustic FlowCaptTM sensors. The data provided nearly continuously so far constitutes the longest dataset of autonomous near-surface (i.e., below 2 m) measurements of drifting snow currently available over the Antarctic continent. This paper presents an assessment of drifting snow occurrences and snow mass transport from up to 9 years (2010–2018) of half-hourly observational records collected in one of the Antarctic regions most prone to snow transport by wind. The dataset is freely available to the scientific community and can be used to complement satellite products and evaluate snow-transport models close to the surface and at high temporal frequency.

scholarly journals Drifting-snow statistics from multiple-year autonomous measurements in Adélie Land, East Antarctica

2020 ◽  
Vol 14 (5) ◽  
pp. 1713-1725 ◽  
Author(s):  
Charles Amory
Keyword(s):  
Temporal Frequency ◽  
Field Measurements ◽  
East Antarctica ◽  
Near Surface ◽  
Continental Scale ◽  
Drifting Snow ◽  
Single Location ◽  
Short Time ◽  
The Antarctic ◽  
Snow Transport

Abstract. Drifting snow is a widespread feature over the Antarctic ice sheet, whose climatological and hydrological significance at the continental scale have been consequently investigated through modelling and satellite approaches. While field measurements are needed to evaluate and interpret model and satellite products, most drifting-snow observation campaigns in Antarctica involved data collected at a single location and over short time periods. With the aim of acquiring new data relevant to the observation and modelling of drifting snow in Antarctic conditions, two remote locations in coastal Adélie Land (East Antarctica) that are 100 km apart were instrumented in January 2010 with meteorological and second-generation IAV Engineering acoustic FlowCapt™ sensors. The data, provided nearly continuously so far, constitute the longest dataset of autonomous near-surface (i.e. within 2 m) measurements of drifting snow currently available over the Antarctic continent. This paper presents an assessment of drifting-snow occurrences and snow mass transport from up to 9 years (2010–2018) of half-hourly observational records collected in one of the Antarctic regions most prone to snow transport by wind. The dataset is freely available to the scientific community and can be used to complement satellite products and evaluate snow-transport models close to the surface and at high temporal frequency.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

scholarly journals Antarctic Surface and Subsurface Snow and Ice Melt Fluxes

2005 ◽  
Vol 18 (10) ◽  
pp. 1469-1481 ◽  
Author(s):  
Glen E. Liston ◽  
Jan-Gunnar Winther
Keyword(s):  
Energy Balance ◽  
Dominant Role ◽  
Field Measurements ◽  
Distribution Model ◽  
Balance Model ◽  
Near Surface ◽  
Production Values ◽  
Surface Melt ◽  
The Antarctic ◽  
Snow And Ice

Abstract This paper presents modeled surface and subsurface melt fluxes across near-coastal Antarctica. Simulations were performed using a physical-based energy balance model developed in conjunction with detailed field measurements in a mixed snow and blue-ice area of Dronning Maud Land, Antarctica. The model was combined with a satellite-derived map of Antarctic snow and blue-ice areas, 10 yr (1991–2000) of Antarctic meteorological station data, and a high-resolution meteorological distribution model, to provide daily simulated melt values on a 1-km grid covering Antarctica. Model simulations showed that 11.8% and 21.6% of the Antarctic continent experienced surface and subsurface melt, respectively. In addition, the simulations produced 10-yr averaged subsurface meltwater production fluxes of 316.5 and 57.4 km3 yr−1 for snow-covered and blue-ice areas, respectively. The corresponding figures for surface melt were 46.0 and 2.0 km3 yr−1, respectively, thus demonstrating the dominant role of subsurface over surface meltwater production. In total, computed surface and subsurface meltwater production values equal 31 mm yr−1 if evenly distributed over all of Antarctica. While, at any given location, meltwater production rates were highest in blue-ice areas, total annual Antarctic meltwater production was highest for snow-covered areas due to its larger spatial extent. The simulations also showed higher interannual meltwater variations for surface melt than subsurface melt. Since most of the produced meltwater refreezes near where it was produced, the simulated melt has little effect on the Antarctic mass balance. However, the melt contribution is important for the surface energy balance and in modifying surface and near-surface snow and ice properties such as density and grain size.

Aspects of modern Antarctic meteorology and climatology

2005 ◽  
Vol 32 (2) ◽  
pp. 334-345
Author(s):  
John Turner
Keyword(s):  
Southern Ocean ◽  
Southern Oscillation ◽  
Coastal Region ◽  
First Century ◽  
Near Surface ◽  
Weather Forecasts ◽  
Air Temperatures ◽  
Oceanic Climate ◽  
Antarctic Continent ◽  
The Antarctic

Great advances have been made in recent years in our understanding of the weather of the Antarctic and how the climate of the continent varies on a range of time-scales. The observations from the stations are still the most accurate meteorological measurements that we have, but satellites have been important in providing data for remote parts of the continent and the Southern Ocean. With the large amount of data that is available today weather forecasts are much more accurate than just a few years ago and can provide valuable guidance up to several days ahead over the Southern Ocean and Antarctic coastal region. However, predicting the weather for the interior of the Antarctic is still very difficult. Recent research has shown that the climate of the Antarctic is affected by tropical atmospheric and oceanic climate cycles, such as the El Niño-Southern Oscillation, but the links are complex. The picture of climate change across the Antarctic during the last 50 years is complex, with only the Antarctic Peninsula showing a significant warming. By the end of the twenty-first century near-surface air temperatures across much of the Antarctic continent are expected to increase by several degrees. A small increase in precipitation is also expected.

scholarly journals A numerical model of blowing snow around an Antarctic building

1994 ◽  
Vol 20 ◽  
pp. 341-346
Author(s):  
I. Moore ◽  
S.D. Mobbs ◽  
D.B. Ingham ◽  
J.C. King
Keyword(s):  
Numerical Model ◽  
Qualitative Agreement ◽  
Progress Report ◽  
Blowing Snow ◽  
Ice Shelf ◽  
British Antarctic Survey ◽  
Drifting Snow ◽  
Antarctic Continent ◽  
Useful Life ◽  
The Antarctic

The accumulation of drifting snow around buildings in regions of severe climate has important implications on their design and location. This paper studies one such building, at a station run by the British Antarctic Survey and located on the Brunt Ice Shelf at the edge of the Antarctic continent. Four previous stations have been built in the area, the buildings of which were designed to become covered in snow and all have been crushed within a few years. The current station, Halley V, consists of three buildings which are all raised from the ice shelf by means of legs. They were designed in such a way that the action of the wind blowing underneath the buildings would keep them-clear of snow. This paper describes a model which predicts the shape and position of drift formation, and then compares the results with those observed at Halley. This model is a first attempt to address the problem and as such the paper can be considered to be a progress report; improvements arc currently being made as part of continuing research. It is found that there is some qualitative agreement and possible reasons for a few quantitative discrepancies are discussed. Both the model and the true data show clearly that the new design is very effective in prolonging the useful life of the buildings.

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

2019 ◽  
Vol 13 (1) ◽  
pp. 281-296 ◽  
Author(s):  
Cécile Agosta ◽  
Charles Amory ◽  
Christoph Kittel ◽  
Anais Orsi ◽  
Vincent Favier ◽  
...  
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Regional Climate ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Drifting Snow ◽  
The Antarctic ◽  
Snow Transport

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 SMB 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 MERRA-2, for the period 1979–2015, and we compare MAR 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 or underestimated 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 drifting snow transport fluxes not included in MAR and probably underestimated in RACMO2 by a factor of 3. Our results tend to confirm that drifting snow transport and sublimation fluxes are much larger than previous model-based estimates and need to be better resolved and constrained in climate models. Sublimation of precipitating particles in low-level atmospheric layers is responsible for the significantly lower snowfall rates in MAR than in RACMO2 in katabatic channels at the ice sheet margins. Atmospheric sublimation in MAR represents 363 Gt yr−1 over the grounded ice sheet for the year 2015, which is 16 % of the simulated snowfall loaded at the ground. This estimate is consistent with a recent study based on precipitation radar observations and is more than twice as much as simulated in RACMO2 because of different time residence of precipitating particles in the atmosphere. The remaining spatial differences in snowfall between MAR and RACMO2 are attributed to differences in advection of precipitation with snowfall particles being likely advected too far inland in MAR.

scholarly journals Reexamination of the Near-Surface Airflow over the Antarctic Continent and Implications on Atmospheric Circulations at High Southern Latitudes*

2007 ◽  
Vol 135 (5) ◽  
pp. 1961-1973 ◽  
Author(s):  
Thomas R. Parish ◽  
David H. Bromwich
Keyword(s):  
Mesoscale Model ◽  
Numerical Models ◽  
Weather Prediction ◽  
Ice Sheets ◽  
Lower Atmosphere ◽  
Diagnostic Model ◽  
Near Surface ◽  
Antarctic Continent ◽  
The Mean ◽  
The Antarctic

Abstract Previous work has shown that winds in the lower atmosphere over the Antarctic continent are among the most persistent on earth with directions coupled to the underlying ice topography. In 1987, Parish and Bromwich used a diagnostic model to depict details of the Antarctic near-surface airflow. A radially outward drainage pattern off the highest elevations of the ice sheets was displayed with wind speeds that generally increase from the high interior to the coast. These winds are often referred to as “katabatic,” with the implication that they are driven by radiational cooling of near-surface air over the sloping ice terrain. It has been shown that the Antarctic orography constrains the low-level wind regime through other forcing mechanisms as well. Dynamics of the lower atmosphere have been investigated increasingly by the use of numerical models since the observational network over the Antarctic remains quite sparse. Real-time numerical weather prediction for the U.S. Antarctic Program has been ongoing since the 2000–01 austral summer season via the Antarctic Mesoscale Prediction System (AMPS). AMPS output, which is based on a polar optimized version of the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model, is used for a 1-yr period from June 2003 to May 2004 to investigate the mean annual and seasonal airflow patterns over the Antarctic continent to compare with previous streamline depictions. Divergent outflow from atop the continental interior implies that subsidence must exist over the continent and a direct thermal circulation over the high southern latitudes results. Estimates of the north–south mass fluxes are obtained from the mean airflow patterns to infer the influence of the elevated ice sheets on the mean meridional circulation over Antarctica.

scholarly journals Evaluation of CloudSat snowfall rate profiles by a comparison with in-situ micro rain radars observations in East Antarctica

2018 ◽  
Author(s):  
Florentin Lemonnier ◽  
Jean-Baptiste Madeleine ◽  
Chantal Claud ◽  
Christophe Genthon ◽  
Claudio Durán-Alarcón ◽  
...  
Keyword(s):  
Climate Models ◽  
Water Reservoir ◽  
Data Sets ◽  
Spatial Average ◽  
Dronning Maud Land ◽  
Antarctic Continent ◽  
Unknown Area ◽  
Short Time ◽  
The Antarctic

Abstract. The Antarctic continent is a vast desert, the coldest and the most unknown area on Earth. It contains the Antarctic ice sheet, the largest continental water reservoir on Earth that could be affected by the current global warming, leading to sea level rise. The only significant supply of ice is through precipitation, which can be observed from the surface and from space. Remote sensing observations of the coastal regions and the inner continent using CloudSat radar give an estimated rate of snowfall but with uncertainties twice as large as each single measured value, whereas climate models give a range from half to twice the time and spatial average observations. The aim of this study is the evaluation of the vertical precipitation rate profiles of CloudSat radar by comparison with two surface-based Micro-Rain Radars (MRR), located at the coastal French Dumont d'Urville station and at the Belgian Princess Elisabeth station, located in the Dronning Maud Land escarpment zone, respectively. This in turn leads to a better understanding and reassessment of CloudSat uncertainties. We compared a total of four precipitation events, two per station, when CloudSat overpassed within 10 km of the stations and we compared these two different data sets at each vertical level. The correlation between both datasets is near-perfect, even though climatic and geographic conditions are different for the stations. Using different CloudSat and MRR vertical levels, we obtain 10km-space and seconds-short-time CloudSat uncertainties from −24 % up to +21 %. This confirms the robustness of the CloudSat retrievals of snowfall over Antarctica above the blind zone and justifies further analyses of this dataset.

scholarly journals Ice Induced Sea Level Change in the Late Neogene

2021 ◽  
Author(s):  
◽  
Gary Steven Wilson
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Level Fluctuation ◽  
Antarctic Ice Sheet ◽  
Continental Scale ◽  
Base Level ◽  
Late Neogene ◽  
Antarctic Continent ◽  
Sea Level Fluctuation ◽  
The Antarctic

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

scholarly journals Ice Induced Sea Level Change in the Late Neogene

2021 ◽  
Author(s):  
◽  
Gary Steven Wilson
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Level Fluctuation ◽  
Antarctic Ice Sheet ◽  
Continental Scale ◽  
Base Level ◽  
Late Neogene ◽  
Antarctic Continent ◽  
Sea Level Fluctuation ◽  
The Antarctic

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

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