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 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 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 Enhanced Moisture Delivery into Victoria Land, East Antarctica During the Early Last Interglacial: Implications for West Antarctic Ice Sheet Stability

2021 ◽  
Author(s):  
Yuzhen Yan ◽  
Nicole E. Spaulding ◽  
Michael L. Bender ◽  
Edward J. Brook ◽  
John A. Higgins ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Ice Age ◽  
Accumulation Rates ◽  
Last Interglacial ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Victoria Land

Abstract. The S27 ice core, drilled in the Allan Hills Blue Ice Area of East Antarctica, is located in Southern Victoria Land ~80 km away from the present-day northern edge of the Ross Ice Shelf. Here, we utilize the reconstructed accumulation rate of S27 covering the Last Interglacial (LIG) period between 129 and 116 thousand years before present (ka) to infer moisture transport into the region. The accumulation rate is based on the ice age-gas age differences calculated from the ice chronology, which is constrained by the stable water isotopes of the ice, and an improved gas chronology based on measurements of oxygen isotopes of O2 in the trapped gases. The peak accumulation rate in S27 occurred at 128.2 ka, near the peak LIG warming in Antarctica. Even the most conservative estimate yields a six-fold increase in the accumulation rate in the LIG, whereas other Antarctic ice cores are typically characterized by a glacial-interglacial difference of a factor of two to three. While part of the increase in S27 accumulation rates must originate from changes in the large-scale atmospheric circulation, additional mechanisms are needed to explain the large changes. We hypothesize that the exceptionally high snow accumulation recorded in S27 reflects open-ocean conditions in the Ross Sea, created by reduced sea ice extent and increased polynya size, and perhaps by a southward retreat of the Ross Ice Shelf relative to its present-day position near the onset of LIG. The proposed ice shelf retreat would also be compatible with a sea-level high stand around 129 ka significantly sourced from West Antarctica. The peak in S27 accumulation rates is transient, suggesting that if the Ross Ice Shelf had indeed retreated during the early LIG, it would have re-advanced by 125 ka.

scholarly journals Spatial–temporal dynamics of chemical composition of surface snow in East Antarctica along the Progress station–Vostok station transect

2014 ◽  
Vol 8 (3) ◽  
pp. 931-939 ◽  
Author(s):  
T. V. Khodzher ◽  
L. P. Golobokova ◽  
E. Yu. Osipov ◽  
Yu. A. Shibaev ◽  
V. Ya. Lipenkov ◽  
...  
Keyword(s):  
Significant Relationship ◽  
High Performance ◽  
Temporal Dynamics ◽  
Accumulation Rate ◽  
Middle Part ◽  
East Antarctica ◽  
Time Interval ◽  
Slope Gradient ◽  
Volcanic Origin ◽  
Surface Snow

Abstract. In January of 2008, during the 53rd Russian Antarctic Expedition, surface snow samples were taken from 13 shallow (0.7 to 1.5 m depth) snow pits along the first tractor traverse from Progress to Vostok stations, East Antarctica. Sub-surface snow/firn layers are dated from 2.1 to 18 yr. The total length of the coast to inland traverse is more than 1280 km. Here we analysed spatial variability of concentrations of sulphate ions and elements and their fluxes in the snow deposited within the 2006–2008 time interval. Anions were analysed by high-performance liquid chromatography (HPLC), and the determination of selected metals, including Na, K, Mg, Ca and Al, was carried out by mass spectroscopy with atomization by induced coupled plasma (ICP-MS). Surface snow concentration records were examined for trends versus distance inland, elevation, accumulation rate and slope gradient. Na shows a significant positive correlation with accumulation rate, which decreases as distance from the sea and altitude increase. K, Ca and Mg concentrations do not show any significant relationship either with distance inland or with elevation. Maximal concentrations of these elements with a prominent Al peak are revealed in the middle part of the traverse (500–600 km from the coast). Analysis of element correlations and atmospheric circulation patterns allow us to suggest their terrestrial origin (e.g. aluminosilicates carried as a continental dust) from the Antarctic nunatak areas. Sulphate concentrations show no significant relationship with distance inland, elevation, slope gradient and accumulation rate. Non-sea salt secondary sulphate is the most important contribution to the total sulphate budget along the traverse. Sulphate of volcanic origin attributed to the Pinatubo eruption (1991) was revealed in the snow pit at 1276 km (depth 120–130 cm).

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.

scholarly journals Iron in ice cores from Law Dome, East Antarctica: implications for past deposition of aerosol iron

1998 ◽  
Vol 27 ◽  
pp. 365-370 ◽  
Author(s):  
R. Edwards ◽  
P. N. Sedwick ◽  
Vin Morgan ◽  
C. F. Boutron ◽  
S. Hong
Keyword(s):  
Southern Ocean ◽  
Late Holocene ◽  
Ice Core ◽  
Iron Concentration ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Iron Deposition ◽  
Past Century ◽  
Preliminary Estimate

Total-dissolvable iron has been measured in sections of three ice cores from Law Dome, East Antarctica, and the results used to calculate atmospheric iron deposition over this region during the late Holocene and to provide a preliminary estimate of aerosol iron deposition during the Last Glaciol Maximum I LGM). Ice-core sections dating from 56-2730 BP (late Holocene) and ~18000 BP (LGM) were decontaminated using trace-metal clean techniques, and total-dissolvable iron was determined in the acidified meltwatcrs by flow-injection analysis. Our results suggest that the atmospheric iron flux onto the Law Dome region has varied significantly over time-scales ranging from seasonal to Glaciol-interglaciol. The iron concentrations in ice-core sections from the past century suggest (1) a 2 4-fold variation in the atmospheric iron flux over a single annual cycle, with the highest flux occurring during the spring and summer, and (2) a nearly 7-fold variation in the annual maximum atmospheric iron flux over a 14 year period. The average estimated atmospheric iron flux calculated from our late-Holocene samples is 0.056-0.14 mg m a−1, which agrees well with Holocene flux estimates derived from aluminium measurements in inland Antarctic ice cores and a recent order-of-magnitude estimate of present-day atmospheric iron deposition over the Southern Ocean. The iron concentration of an ice-corc section dating from the LGM was more than 50 times higher than in the late-Holocene ice samples. Using a snow-accumulation rate estimate of 130 kg m −2 a−1 for this period, we calculate 0.87 mgm −2 a−1 as a preliminary estimate of atmospheric iron deposition during the LGM, which is 6-16 times greater than our average late-Holocene iron flux. Our data are consistent with the suggestion that there was a significantly greater flux of atmospheric iron onto the Southern Ocean during the LGM than during then Holocene.

scholarly journals A 2000-year annual record of snow accumulation rates for Law Dome, East Antarctica

2015 ◽  
Vol 11 (5) ◽  
pp. 697-707 ◽  
Author(s):  
J. Roberts ◽  
C. Plummer ◽  
T. Vance ◽  
T. van Ommen ◽  
A. Moy ◽  
...  
Keyword(s):  
Southern Oscillation ◽  
Accumulation Rate ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Accumulation Rates ◽  
Annual Layer ◽  
Decadal Scale ◽  
Ice Sheet Mass Balance ◽  
The Law ◽  
Rate Profile

Abstract. Accurate high-resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to the mid-latitudes as well as regional Antarctic snowfall. Here, we extend the length of the Law Dome accumulation record from 750 years to 2035 years, using recent annual layer dating that extends to 22 BCE. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long-term mean accumulation rate. The modelled layer thicknesses were based on a power-law vertical strain rate profile fitted to observed annual layer thickness. The periods 380–442, 727–783 and 1970–2009 CE have above-average snow accumulation rates, while 663–704, 933–975 and 1429–1468 CE were below average, and decadal-scale snow accumulation anomalies were found to be relatively common (74 events in the 2035-year record). The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger-scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to El Niño–Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO) frequencies.

scholarly journals Retention and radiative forcing of black carbon in eastern Sierra Nevada snow

2013 ◽  
Vol 7 (1) ◽  
pp. 365-374 ◽  
Author(s):  
K. M. Sterle ◽  
J. R. McConnell ◽  
J. Dozier ◽  
R. Edwards ◽  
M. G. Flanner
Keyword(s):  
Black Carbon ◽  
Sierra Nevada ◽  
Radiative Forcing ◽  
Major Ions ◽  
Snow Accumulation ◽  
Radiation Balance ◽  
Surface Snow ◽  
Dust Surface ◽  
Snow Samples ◽  
Eastern Sierra Nevada

Abstract. When contaminated by absorbing particles, such as refractory black carbon (rBC) and continental dust, snow's albedo decreases and thus its absorption of solar radiation increases, thereby hastening snowmelt. For this reason, an understanding of rBC's affect on snow albedo, melt processes, and radiation balance is critical for water management, especially in a changing climate. Measurements of rBC in a sequence of snow pits and surface snow samples in the eastern Sierra Nevada of California during the snow accumulation and ablation seasons of 2009 show that concentrations of rBC were enhanced sevenfold in surface snow (~25 ng g–1) compared to bulk values in the snowpack (~3 ng g–1). Unlike major ions, which were preferentially released during the initial melt, rBC and continental dust were retained in the snow, enhancing concentrations well into late spring, until a final flush occurred during the ablation period. We estimate a combined rBC and continental dust surface radiative forcing of 20 to 40 W m−2 during April and May, with dust likely contributing a greater share of the forcing.

Snow accumulation rate and atmospheric oxidation pathway proxies from nitrate isotopes in East Antarctica

2020 ◽  
Author(s):  
Pete Akers ◽  
Joël Savarino ◽  
Nicolas Caillon
Keyword(s):  
Oxygen Isotope ◽  
Accumulation Rate ◽  
Isotopic Fractionation ◽  
Ice Cores ◽  
Snow Accumulation ◽  
East Antarctica ◽  
Atmospheric Oxidation ◽  
High Accumulation ◽  
Antarctic Snow ◽  
History Of

<p>Nitrate is naturally deposited in Antarctic snow and is detectable at low concentrations throughout our deepest ice cores. However, nitrate is photoreactive under ultraviolet light and experiences significant post-depositional loss. This nitrate loss favors 14NO3- over 15NO3-, and the resulting isotopic fractionation can be used as a proxy for duration of sunlight exposure. Here, we present nitrate isotope data (δ15N, δ18O, Δ17O) sampled from shallow snow cores and pits across East Antarctica. Our >30 sampling sites extend from coastal Adélie Land onto the high East Antarctic Plateau at Dome C and beyond, covering annual snow mass balances that range from 240 mm/yr to less than 30 mm/yr (water equivalent). The δ15N of nitrate at these sites show an inverse relationship with snow accumulation rate, with δ15N ≈ 20‰ at the coastal sites with the highest accumulations and δ15N ≈ 150-250‰ at the driest inland sites. This relationship develops because newly deposited nitrate is buried below the level of light penetration by new snow relatively quickly at high accumulation sites, but nitrate at drier sites can be exposed to sunlight for several years. After burial below the reach of sunlight, the δ15N signature of nitrate is preserved and thus offers a new proxy for snow accumulation rate in East Antarctic ice cores. In contrast, the oxygen isotopes of nitrate isotopically exchange with surrounding ice after burial, which complicates their interpretation. However, our large sample set allows an estimation of the rate of isotopic exchange at various sites, and the original isotopic values at the time of deposition may be approximated after correcting for this rate of exchange. These oxygen isotope values likely reflect in part the atmospheric oxidation history of the nitrate and its nitrogen oxide progenitor, but further study is needed to fully understand nitrate oxygen isotope dynamics.</p>

scholarly journals Snow accumulation rates in northern Victoria Land, Antarctica, by firn-core analysis

2000 ◽  
Vol 46 (155) ◽  
pp. 541-552 ◽  
Author(s):  
Barbara Stenni ◽  
Francesca Serra ◽  
Massimo Frezzotti ◽  
Valter Maggi ◽  
Rita Traversi ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Katabatic Wind ◽  
Climatic Data ◽  
Accumulation Rates ◽  
Surface Mass ◽  
Physical Study ◽  
Victoria Land ◽  
The Mean

AbstractA multiparametric (chemical, isotopic and physical) study on three shallow firn cores sampled in northern Victoria Land was carried out to obtain glaciological information and climatic data in this Antarctic region. Sampling areas were accurately prospected to identify sites, located at different altitudes and distances from the sea, where the snow accumulation was not influenced by katabatic wind redistribution or summer melting. Stratigraphic, isotopic (δl8O) and chemical (H2O2, MSA and nssSO42−) profiles were mutually examined for dating purposes and to determine the mean snow-accumulation rates at three different stations. Annual accumulation rates of 85–420 kg m−2 a−1 were determined in the period 1971–92. An inverse pattern between accumulation rate and altitude was shown by the progression of the mean annual rates of 160, 203 and 260 kg m−2 a−1, respectively, in the highest, medium and lowest stations. The mean accumulation value of all northern Victoria Land data available, 170 kg m−2 a−1, represents a decrease of up to 35% with respect to the estimated value most widely used until now. Our accumulation value is very close to that required for a zero net surface mass balance according to ice discharge. A linear relationship with a gradient of 0.81‰ °C−1 has been found between mean δ18O values and mean annual surface temperature for different ice cores drilled in northern Victoria Land.

Sign in / Sign up

Export Citation Format

Share Document