scholarly journals Nitrate deposition and preservation in the snowpack along a traverse from coast to the ice sheet summit (Dome A) in East Antarctica

2017 ◽  
Author(s):  
Guitao Shi ◽  
Meredith G. Hastings ◽  
Jinhai Yu ◽  
Tianming Ma ◽  
Zhengyi Hu ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Aerosol Particles ◽  
Deposition Velocity ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Dome A ◽  
Surface Snow ◽  
Coexisting Ions ◽  
Snow Samples

Abstract. The Antarctic ice core nitrate (NO3−) can provide a unique record of the atmospheric reactive nitrogen cycle. However, the factors influencing the deposition and preservation of NO3− at the ice sheet surface must first be understood. Therefore, an intensive program of snow sample collections was made on a traverse from the coast to the ice sheet summit, Dome A, East Antarctica. Snow samples in this observation include 120 surface snow samples (top ~ 3 cm), 20 snowpits with depths of 150 to 300 cm, and 6 crystal ice samples (the topmost needle like layer on Dome A plateau), and NO3− concentrations in these samples were determined. The main purpose of this investigation is to characterize the distribution pattern and preservation of NO3− in the snow in different environments. Results show that an increasing trend of NO3− concentrations with distance inland is present in surface snow, and NO3− is extremely enriched in the crystal ice (with a maximum of 16.1 μeq L−1). NO3− concentration profiles for snowpits vary between coastal and inland sites. On the coast, the deposited NO3− was largely preserved, and the archived NO3− fluxes are dominated by snow accumulation. The relationship between the archived NO3− and snow accumulation rate can be well depicted by a linear model, suggesting a homogeneity of atmospheric NO3− levels. It is estimated that dry deposition contributes 27−44 % of the archived NO3− fluxes, and the dry deposition velocity and scavenging ratio for NO3− was relatively constant near the coast. Compared to the coast, the inland snow shows a relatively weak association between archived NO3− and snow accumulation, and the archived NO3− fluxes were more concentration dependent. The association between NO3− and the coexisting ions (nssSO42−, Na+ and Cl−) was assessed, and nssSO42− (the fine aerosol particles) could potentially influence NO3− concentrations, while the correlation between NO3− and Na+ (mainly associated with coarse aerosol particles) is not significant. In inland snow, there were no significant relationships found between NO3− and the coexisting ions, suggesting a dominant role of NO3− recycling in the concentration.

scholarly journals Nitrate deposition and preservation in the snowpack along a traverse from coast to the ice sheet summit (Dome A) in East Antarctica

2018 ◽  
Vol 12 (4) ◽  
pp. 1177-1194 ◽  
Author(s):  
Guitao Shi ◽  
Meredith G. Hastings ◽  
Jinhai Yu ◽  
Tianming Ma ◽  
Zhengyi Hu ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Aerosol Particles ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Dome A ◽  
Surface Snow ◽  
The Relationship ◽  
Coexisting Ions ◽  
Snow Samples

Abstract. Antarctic ice core nitrate (NO3-) can provide a unique record of the atmospheric reactive nitrogen cycle. However, the factors influencing the deposition and preservation of NO3- at the ice sheet surface must first be understood. Therefore, an intensive program of snow and atmospheric sampling was made on a traverse from the coast to the ice sheet summit, Dome A, East Antarctica. Snow samples in this observation include 120 surface snow samples (top ∼ 3 cm), 20 snow pits with depths of 150 to 300 cm, and 6 crystal ice samples (the topmost needle-like layer on Dome A plateau). The main purpose of this investigation is to characterize the distribution pattern and preservation of NO3- concentrations in the snow in different environments. Results show that an increasing trend of NO3- concentrations with distance inland is present in surface snow, and NO3- is extremely enriched in the topmost crystal ice (with a maximum of 16.1 µeq L−1). NO3- concentration profiles for snow pits vary between coastal and inland sites. On the coast, the deposited NO3- was largely preserved, and the archived NO3- fluxes are dominated by snow accumulation. The relationship between the archived NO3- and snow accumulation rate can be depicted well by a linear model, suggesting a homogeneity of atmospheric NO3- levels. It is estimated that dry deposition contributes 27–44 % of the archived NO3- fluxes, and the dry deposition velocity and scavenging ratio for NO3- were relatively constant near the coast. Compared to the coast, the inland snow shows a relatively weak correlation between archived NO3- and snow accumulation, and the archived NO3- fluxes were more dependent on concentration. The relationship between NO3- and coexisting ions (nssSO42-, Na+ and Cl−) was also investigated, and the results show a correlation between nssSO42- (fine aerosol particles) and NO3- in surface snow, while the correlation between NO3- and Na+ (mainly associated with coarse aerosol particles) is not significant. In inland snow, there were no significant relationships found between NO3- and the coexisting ions, suggesting a dominant role of NO3- recycling in determining the concentrations.

scholarly journals Climate variability along latitudinal and longitudinal transects in East Antarctica

2004 ◽  
Vol 39 ◽  
pp. 351-358 ◽  
Author(s):  
Olivier Magand ◽  
Massimo Frezzotti ◽  
Michel Pourchet ◽  
Barbara Stenni ◽  
Laura Genoni ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Accumulation Rate ◽  
Source Region ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Lapse Rate ◽  
Katabatic Wind ◽  
Surface Snow ◽  
Borehole Temperatures ◽  
Snow Samples

AbstractIn the framework of the International Trans-Antarctic Scientific Expedition (ITASE) programme, France and Italy carried out a traverse along one west–east and two north–south transects in East Antarctica from November 2001 to January 2002. Eighteen shallow snow–firn cores were drilled, and surface snow samples were collected every 5km along the traverse. Firn temperatures were measured in boreholes down to 30 m. The cores were analyzed for β radioactivity to obtain snow accumulation-rate data. The surface snow samples were analyzed for δ18O to correlate isotopic values with borehole temperatures. Multiple regression analysis shows a global near-dry-adiabatic lapse rate and a latitudinal lapse rate of 1.05˚C(˚ lat. S)–1, in the Dome C drainage area. Analysis of firn temperatures reveals a super-adiabatic lapse rate along the ice divide between Talos Dome and the Southern Ocean coast, and in some sectors along the ice divide between the Astrolabe Basin and D59. Snow accumulation rates and firn temperatures show warmer temperatures and higher accumulation values close to the ice divides extending from Talos Dome and Dome C to the Southern Ocean. The spatial pattern of data is linked with a katabatic-wind-source basin and moisture-source region.

scholarly journals Spatial and temporal variations in snow chemistry along a traverse from coastal East Antarctica to the ice sheet summit (Dome A)

2020 ◽  
Author(s):  
Guitao Shi ◽  
Hongmei Ma ◽  
Zhengyi Hu ◽  
Zhenlou Chen ◽  
Chunlei An ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Temporal Variations ◽  
East Antarctica ◽  
Spatial And Temporal Variations ◽  
Biogenic Emissions ◽  
Dome A ◽  
Sea Salts ◽  
Snow Chemistry ◽  
Winter Snow ◽  
Surface Snow

Abstract. There is a large variability in environmental conditions across the Antarctic ice sheet, and it is of significance to investigate the snow chemistry at as many locations as possible and over time, given that the ice sheet itself, and precipitation and deposition patterns and trends are changing. The China inland Antarctic traverse from coastal Zhongshan Station to the ice sheet summit (Dome A) covers a variety of environments, allowing for a vast collection of snow chemistry conditions across East Antarctica. Surface snow and snow pit samples were collected on this traverse during five campaigns, to comprehensively investigate the spatial and temporal variations in chemical ions (Cl−, NO3−, SO42−, Na+, NH4+, K+, Mg2+, and Ca2+) and the related controlling factors. Results show that spatial patterns of ions in surface snow are consistent among the five campaigns, with Cl−, Na+, K+, and Mg2+ decreasing rapidly with distance from the coast and NO3− showing an opposite pattern. No clear spatial trends in SO42−, NH4+ and Ca2+ were found. In the interior areas, an enrichment of Cl− versus Na+ with respect to seawater composition is ubiquitous as a result of the deposition of HCl, which can account for up to ~40 % of the total Cl− budget, while enriched K+ and Mg2+ are associated with terrestrial particle mass. Ca2+ and SO42− in surface snow are significantly enriched relative to Na+, related to terrestrial dust inputs and marine biogenic emissions, respectively. Snow NH4+ is mainly associated with marine biological activities, with higher concentrations in summer than in winter. On the coast, parts of the winter snow are characterized with a depletion of SO42− versus Na+, and a significant negative correlation between nssSO42− and Na+ was found, suggesting that sea salts originated from the sea ice. In the interior areas, the negative nssSO42− signal in winter snow resulted from inputs of sea salts being completely swamped by the contribution of marine biogenic emissions. Ternary plots of Cl−, Na+, and SO42− suggest that sea salt modification is generally negligible on the coast, while the degree of modification processes to sea salts is high in the interior areas, especially during the summertime. Ion flux assessment suggests an efficient transport of nssSO42− to at least as far inland as the ~2800 m contour line. The interannual variations in ion concentrations in surface snow on the traverse are likely linked to the changes in the Southern Indian Ocean low (SIOL) from year to year, and the deepening of the SIOL in summer tends to promote the transport of marine aerosols to Princess Elizabeth Land.

scholarly journals Snow surface height variations on the Antarctic ice sheet in Princess Elizabeth Land, Antarctica: 1 year of data from an automatic weather station

2004 ◽  
Vol 39 ◽  
pp. 181-187 ◽  
Author(s):  
Qin Dahe ◽  
Xiao Cunde ◽  
Ian Allison ◽  
Bian Lingen ◽  
Rod Stephenson ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Cloud Amount ◽  
Snow Accumulation ◽  
Strong Wind ◽  
Weather Station ◽  
Automatic Weather Station ◽  
Antarctic Ice Sheet ◽  
Total Cloud Amount ◽  
Surface Snow ◽  
The Antarctic

AbstractThe net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation and wind redistribution. We present a 1 year record of hourly snow-height measurements that shows its seasonal variability. The measurements were made with an ultrasonic sensor mounted on an automatic weather station (AWS) installed at LGB69, Princess Elizabeth Land, Antarctica (70.835˚S, 77.075˚E; 1850 ma.s.l.). The average accumulation at this site is approximately 0.70 m snow a–1. Throughout the winter, between April and September, there was little change in surface snow height. The strongest accumulation occurred during the period October–March, with four episodic increases occurring during 2002. These episodic events coincided with obvious humidity ‘pulses’ and decreases of incoming solar radiation as recorded by the AWS. Observations of the total cloud amount at Davis station, 160 km north-northeast of LGB69, showed good correlation with major accumulation events recorded at LGB69. There was an obvious anticorrelation between the lowest cloud height at Davis and the daily accumulation rate at LGB69. Although there was no correlation over the total year between wind speed and accumulation at LGB69, large individual accumulation events are associated with episodes of strong wind. Strong accumulation events at LGB69 are associated with major storms in the region and inland transport of moist air masses from the coast.

scholarly journals The Weddell Sea region: an important precipitation channel to the interior of the Antarctic ice sheet as revealed by glaciochemical investigation of surface snow along the longest trans-Antarctic route

1999 ◽  
Vol 29 ◽  
pp. 55-60 ◽  
Author(s):  
Qin Dahe ◽  
Paul A. Mayewski ◽  
Ren Jiawen ◽  
Xiao Cunde ◽  
Sun Junying
Keyword(s):  
Ice Sheet ◽  
Weddell Sea ◽  
Sea Salt ◽  
East Antarctica ◽  
Antarctic Ice Sheet ◽  
Air Masses ◽  
Antarctic Plateau ◽  
Salt Ions ◽  
Surface Snow ◽  
The Antarctic

AbstractGlaciochemical analysis of surface snow samples, collected along a profile crossing the Antarctic ice sheet from the Larsen Ice Shelf, Antarctic Peninsula, via the Antarctic Plateau through South Pole, Vostok and Komsomolskaya to Mirny station (at the east margin of East Antarctica), shows that the Weddell Sea region is an important channel for air masses to the high plateau of the Antarctic ice sheet (>2000 m a.s.l.). This opinion is supported by the following. (1) The fluxes of sea-salt ions such as Na+, Mg2 + and CF display a decreasing trend from the west to the east of interior Antarctica. In |eneral, as sea-salt aerosols are injected into the atmosphere over the Antarctic ice sheet from the Weddell Sea, large aerosols tend to decrease. For the inland plateau, few large particles of sea-salt aerosol reach the area, and the sea-salt concentration levels are low (2) The high altitude of the East Antarctic plateau, as well as the polar cold high-pressure system, obstruct the intrusive air masses mainly from the South Indian Ocean sector. (3) For the coastal regions of the East Antarctic ice sheet, the elevation rises to 2000 m over a distance from several to several tens of km. High concentrations of sea salt exist in snow in East Antarctica but are limited to a narrow coastal zone. (4) Fluxes of calcium and non-sea-salt sulfate in snow from the interior plateau do not display an eastward-decreasing trend. Since calcium is mainly derived from crustal sources, and nssSO42- is a secondary aerosol, this again confirms that the eastward-declining tendency of sea-salt ions indicates the transfer direction of precipitation vapor.

scholarly journals Identification of multiple natural and anthropogenic sources of dust in snow from Zhongshan Station to Dome A, East Antarctica

2018 ◽  
Vol 64 (248) ◽  
pp. 855-865 ◽  
Author(s):  
ZHIHENG DU ◽  
CUNDE XIAO ◽  
MINGHU DING ◽  
CHUANJIN LI
Keyword(s):  
Major Ions ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
East Antarctica ◽  
Anthropogenic Sources ◽  
Dome A ◽  
Long Distance ◽  
Anthropogenic Pollutants ◽  
Zhongshan Station ◽  
Snow Samples

ABSTRACTThe stable oxygen isotope composition, major ions and isotopic compositions of strontium (Sr), neodymium (Nd) and lead (Pb) in insoluble dust from recent surface snow samples along the transect from the Zhongshan and Progress stations (located on the Amery Ice Shelf, East Antarctica) to Dome A (Summit, Antarctica) were analysed. No previous isotopic fingerprinting studies have been conducted for this transect. These data were used to document the dust provenances in Antarctica along the transect up to the highest site, Dome A, for the first time. The insoluble dust in snow samples along the coast displays an overall crust-line isotopic signature that is characterised by highly radiogenic 87Sr/86Sr values and less radiogenic 143Nd/144Nd values. These signatures are comparable with those of samples collected near the ice-free areas of the Zhongshan and Progress stations. Spatial differences are statistically significant along the transect, and the Sr, Nd and Pb isotope components in insoluble dust from two continuous snow samples at Dome A exhibit marked differences, indicating that additional dust reaches the East Antarctic Plateau. The isotopic characteristics of insoluble dust from this transect indicate that the long-distance natural dust and anthropogenic pollutants in these samples primarily originate from Australia.

Glaciochemistry of surface snow from the Ingrid Christensen Coast, East Antarctica, and its environmental implications

2010 ◽  
Vol 22 (4) ◽  
pp. 435-441 ◽  
Author(s):  
M. Thamban ◽  
C.M. Laluraj ◽  
K. Mahalinganathan ◽  
B.L. Redkar ◽  
S.S. Naik ◽  
...  
Keyword(s):  
Biological Activities ◽  
Enrichment Factors ◽  
Sea Salt ◽  
East Antarctica ◽  
Sea Spray ◽  
Environmental Implications ◽  
Study Region ◽  
Surface Snow ◽  
Crustal Contribution ◽  
Snow Samples

AbstractSpatial variations in the ion composition were studied in 55 surface snow samples collected along three transects in the Ingrid Christensen Coast of East Antarctica. The sea-salt ion constituents revealed a drastic reduction from the ice edge to inland sites. The computed sea-salt sodium and non-sea-salt calcium concentrations suggest that while sea spray primarily contributes to the Na+, the crustal contribution dominates the Ca2+ in snow samples. The Cl-/ssNa+ ratios of the snow samples from the Larsemann transect varied between 4.7 and 1.05, indicating that additional Cl- sources like soil dust are important in the inland sites. The enrichment factors (Ef) confirm a dominant crustal source for Ca2+ in all transects. The Ef(K+) values indicate a dominant sea spray source for K+ in the coastal stations of the Larsemann and Publications transects. The Ef(Mg2+) values indicate the absence of any significant Mg2+ enrichment compared to seawater values. Secondary sulphur species (nssSO42- and MSA) within the snow samples suggest that both vary independently of each other, possibly influenced by the local biological activities. The nssSO42- data revealed that several summer snow deposits in the study region are significantly fractionated, apparently related to the sea ice existence during summer.

Thermodynamics of the interaction between ice shelves and the sea

Polar Record ◽  
1976 ◽  
Vol 18 (112) ◽  
pp. 37-41 ◽  
Author(s):  
C. S. M. Doake
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
Surface Snow ◽  
Seaward Edge ◽  
The Antarctic

An ice shelf is a floating ice sheet, attached to land where ice is grounded along the coastline. Nourished both by surface snow accumulation and by glaciers and ice sheets flowing off the land, ice shelves can reach a considerable thickness, varying from up to 1 300 m when the ice starts to float to 200 m or less at the seaward edge (known as the ice front). Nearly all the world's ice shelves are found in Antarctica, where they cover an area of about one and a half million square kilometres. The two largest are the Ross Ice Shelf and the Filchner-Ronne ice shelf, each with an area of about half a million square kilometres. Smaller ice shelves fringe other parts of the Antarctic coastline.

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