High-resolution 900 year volcanic and climatic record from the Vostok area, East Antarctica

Abstract. Ion chromatography measurements of 1730 snow and firn samples obtained from three short cores and one pit in the Vostok station area, East Antarctica, allowed for the production of the combined volcanic record of the last 900 years (AD 1093–2010). The resolution of the record is 2–3 samples per accumulation year. In total, 24 volcanic events have been identified, including seven well-known low-latitude eruptions (Pinatubo 1991, Agung 1963, Krakatoa 1883, Tambora 1815, Huanaputina 1600, Kuwae 1452, El Chichon 1259) found in most of the polar ice cores. In comparison with three other East Antarctic volcanic records (South Pole, Plateau Remote and Dome C), the Vostok record contains more events within the last 900 years. The differences between the records may be explained by local glaciological conditions, volcanic detection methodology, and, probably, differences in atmospheric circulation patterns. The strongest volcanic signal (both in sulfate concentration and flux) was attributed to the AD 1452 Kuwae eruption, similar to the Plateau Remote and Talos Dome records. The average snow accumulation rate calculated between volcanic stratigraphic horizons for the period AD 1260–2010 is 20.9 mm H2O. Positive (+13%) anomalies of snow accumulation were found for AD 1661–1815 and AD 1992–2010, and negative (−12%) for AD 1260–1601. We hypothesized that the changes in snow accumulation are associated with regional peculiarities in atmospheric transport.

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High resolution 900 yr volcanic and climatic record from the Vostok area, East Antarctica

The Cryosphere Discussions ◽

10.5194/tcd-7-1961-2013 ◽

2013 ◽

Vol 7 (3) ◽

pp. 1961-1986 ◽

Cited By ~ 2

Author(s):

E. Yu. Osipov ◽

T. V. Khodzher ◽

L. P. Golobokova ◽

N. A. Onischuk ◽

V. Ya. Lipenkov ◽

...

Keyword(s):

High Resolution ◽

Environmental Changes ◽

Atmospheric Transport ◽

Accumulation Rate ◽

Ice Cores ◽

High Sensitivity ◽

Snow Accumulation ◽

East Antarctica ◽

Positive Trend ◽

Decadal Scale

Abstract. Detailed volcanic record of the last 900 yr (1093–2010 AD) has been received using high resolution (2–3 samples per accumulation year) sulfate measurements in four snow/firn cores from the Vostok station area, East Antarctica. Totally, 33 volcanic events have been identified in the record, including well-known low latitude eruption signals found in many polar ice cores (e.g., Pinatubo 1991, Agung 1963, Krakatoa 1883, Tambora 1815, Huanaputina 1600, Kuwae 1452), however in comparison with other Antarctic sites the record has more events covering the last 900 yr. The strongest volcanic signals occurred during mid-13th, mid-15th and 18th centuries. The largest volcanic signal of Vostok (both in sulfate concentration and flux) is the 1452 AD Kuwae eruption. Average snow accumulation rate calculated for the period 1093–2010 AD is 21.3 ± 2.3 mm H2O. Accumulation record demonstrates a slight positive trend, however sharply increased accumulation rate during the periods from 1600 to 1815 AD (by 11% from long-term mean) and from 1963 to 2010 AD (by 15%) are typical features of the site. Na+ record shows strong decadal-scale variability probably connected with coupled changes in atmospheric transport patterns over Antarctica (meridional circulation change) and local glaciology. The obtained high resolution climatic records suggest a high sensitivity of the Vostok location to environmental changes in Southern Hemisphere.

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

10.5194/cp-2021-7 ◽

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.

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Spatial variability of snow isotopic composition and accumulation rate at the stake farm of Vostok station (Сentral Antarctica)

Arctic and Antarctic Research ◽

10.30758/0555-2648-2019-65-1-46-62 ◽

2019 ◽

Vol 65 (1) ◽

pp. 46-62 ◽

Cited By ~ 1

Author(s):

A. A. Ekaykin ◽

D. O. Vladimirova ◽

N. A. Tebenkova ◽

E. V. Brovkov ◽

A. N. Veres ◽

...

Keyword(s):

Spatial Distribution ◽

Spatial Variability ◽

Isotopic Composition ◽

Accumulation Rate ◽

Ice Sheet ◽

Ice Cores ◽

Snow Accumulation ◽

Geochemical Data ◽

Snow Surface ◽

Vostok Station

The knowledge of the spatial distribution of the snow accumulation rate and isotopic composition in different scales, from local to continental, over the Antarctic Ice Sheet is critically important for the interpretation of the paleoclimate data obtained from deep ice cores, for correct assessment of the ice sheet mass balance, etc. With this in mind, we have synthesized geodetic, glaciological and geochemical data collected in the vicinity of central Antarctic Vostok station in 1970–2017 in order to shed light on the processes governing the spatial distribution of snow isotopic composition and accumulation rate in the spatial scale from 100 to 1000 m. First, we have discovered that snow surface height and snow accumulation rate field are strongly affected by the influence of the logistic convoy route annually operating between Russian Antarctic stations Vostok and Progress. This influence is detectable up to 1 km leeward from the route. At the same time the isotopic composition of the upper 10 cm of the snow does not show any anomalies in the vicinity of the route. This is an unexpected result, because large anomalies of the ice sheet surface (e.g., megadunes) are known to affect the snow isotopic composition. Second, in the undisturbed part of the snow surface near Vostok station we have discovered quasi-periodic (with the wavelength of about 400 m) low-amplitude variations of the surface height that are covariant with the corresponding waves in snow accumulation and isotopic composition. We suggest that spatial variability of the snow isotopic composition is due to the different ratio of summer and winter precipitation deposited in different locations, as evident from a strong negative correlation between δD and dxs parameters. The results of this study may explain the nature of the low-frequency noise (with the time-scale from decades to centuries) observed in the climate records obtained from shallow and deep ice cores in central Antarctica.

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

10.5194/egusphere-egu2020-9109 ◽

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

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 (&#948;15N, &#948;18O, &#916;17O) sampled from shallow snow cores and pits across East Antarctica. Our >30 sampling sites extend from coastal Ad&#233;lie 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 &#948;15N of nitrate at these sites show an inverse relationship with snow accumulation rate, with &#948;15N &#8776; 20&#8240; at the coastal sites with the highest accumulations and &#948;15N &#8776; 150-250&#8240; 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 &#948;15N 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.

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Spatial variability at shallow snow-layer depths in central Dronning Maud Land, East Antarctica

Annals of Glaciology ◽

10.3189/172756499781820905 ◽

1999 ◽

Vol 29 ◽

pp. 10-16 ◽

Cited By ~ 32

Author(s):

Cecilia Richardson ◽

Per Holmlund

Keyword(s):

Spatial Variability ◽

Accumulation Rate ◽

Marked Change ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Snow Layer ◽

Accumulation Pattern ◽

Single Action ◽

Dronning Maud Land

AbstractThe spatial variability in snow accumulation varies between different regions in Dronning Maud Land, East Antarctica. This pattern cannot easily be explained by the single action of parameters such as distance to open sea, surface elevation or slope. In 1996-97 we mapped snow-layer depths within the top 11 m of the snowpack with a ground-based radar along a 500 km traverse on the polar plateau in central Dronning Maud Land. The results showed that the general accumulation pattern could be described by three major characteristic sections: a pronounced trend of decreasing net accumulation with increasing altitude from 2400 to 2840 m a.s.l.; relatively high erosion rates and occurrence of areas with net erosion at 2840-3140 m a.s.l.; and a slight trend of decreasing net accumulation with increasing altitude from 3140 to 3450 m a.s.l. The spatial variability in snow-layer depths showed a marked change around 3080 m a.s.l., with high variability at lower elevations and low variability at higher elevations. We also determined the spatial representativeness of 11 firn cores drilled along the traverse. In general, the representativeness of the cores was high. However, the core with the lowest representativeness underestimated the mean accumulation rate around the coring site by 22%. This shows that snow-radar data on spatial snow distribution are important for the interpretation of accumulation rates obtained from firn and ice cores.

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Non-climatic signal in ice core records: lessons from Antarctic megadunes

The Cryosphere ◽

10.5194/tc-10-1217-2016 ◽

2016 ◽

Vol 10 (3) ◽

pp. 1217-1227 ◽

Cited By ~ 4

Author(s):

Alexey Ekaykin ◽

Lutz Eberlein ◽

Vladimir Lipenkov ◽

Sergey Popov ◽

Mirko Scheinert ◽

...

Keyword(s):

Spatial Variability ◽

Isotopic Composition ◽

Vertical Profile ◽

Accumulation Rate ◽

Climatic Variability ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Vostok Station ◽

Isotope Content

Abstract. We present the results of glaciological investigations in the megadune area located 30 km to the east of Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the megadune ridge accompanied by precise GPS altitude measurements and ground penetrating radar (GPR) survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance < 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (22 mm w.e.) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the megadunes compared to the surrounding plateau. The snow isotopic composition is in negative correlation with the snow accumulation. Analysing dxs ∕ δD and 17O-excess ∕ δD slopes (where dxs =  δD − 8 ⋅ δ18O and 17O-excess  =  ln(δ17O  ∕  1000 + 1) −0.528 ⋅ ln (δ18O ∕ 1000 + 1)), we conclude that the spatial variability of the snow isotopic composition in the megadune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr−1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, a core drilled in the megadune area would exhibit the non-climatic 410-year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the megadune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the megadune areas.

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Non-climatic signal in ice core records: lessons from Antarctic mega-dunes

The Cryosphere Discussions ◽

10.5194/tcd-9-6909-2015 ◽

2015 ◽

Vol 9 (6) ◽

pp. 6909-6936

Author(s):

A. Ekaykin ◽

L. Eberlein ◽

V. Lipenkov ◽

S. Popov ◽

M. Scheinert ◽

...

Keyword(s):

Spatial Variability ◽

Isotopic Composition ◽

Vertical Profile ◽

Accumulation Rate ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Vostok Station ◽

Isotope Content ◽

Dune Area

Abstract. We present the results of glaciological investigations in the mega-dune area located 30 km to the east from Vostok Station (central East Antarctica) implemented during the 58th, 59th and 60th Russian Antarctic Expedition (January 2013–January 2015). Snow accumulation rate and isotope content (δD, δ18O and δ17O) were measured along the 2 km profile across the mega-dune ridge accompanied by precise GPS altitude measurements and GPR survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by one order of magnitude within the distance < 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (22 mm we) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the mega-dunes compared to the surrounding plateau. The snow isotopic composition is in negative correlation with the snow accumulation. Analyzing dxs/δD and 17O-excess/δD slopes, we conclude that the spatial variability of the snow isotopic composition in the mega-dune area could be explained by post-depositional snow modifications. Using the GPR data, we estimated the apparent dune drift velocity (4.6 ± 1.1 m yr−1). The full cycle of the dune drift is thus about 410 years. Since the spatial anomalies of snow accumulation and isotopic composition are supposed to drift with the dune, an ice core drilled in the mega-dune area would exhibit the non-climatic 410 year cycle of these two parameters. We simulated a vertical profile of snow isotopic composition with such a non-climatic variability, using the data on the dune size and velocity. This artificial profile is then compared with the real vertical profile of snow isotopic composition obtained from a core drilled in the mega-dune area. We note that the two profiles are very similar. The obtained results are discussed in terms of interpretation of data obtained from ice cores drilled beyond the mega-dune areas.

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Enhanced moisture delivery into Victoria Land, East Antarctica, during the early Last Interglacial: implications for West Antarctic Ice Sheet stability

Climate of the Past ◽

10.5194/cp-17-1841-2021 ◽

2021 ◽

Vol 17 (5) ◽

pp. 1841-1855

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 ka and 116 ka (where ka indicates thousands of years before present) 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 an order-of-magnitude increase in the accumulation rate during the LIG maximum, whereas other Antarctic ice cores are typically characterized by a glacial–interglacial difference of a factor of 2 to 3. 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 the 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.

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Reconstructing Antarctic snow accumulation using nitrogen isotopes of nitrate

10.5194/egusphere-egu21-672 ◽

2021 ◽

Author(s):

Pete D. Akers ◽

Joël Savarino ◽

Nicolas Caillon ◽

Mark Curran ◽

Tas Van Ommen

Keyword(s):

Nitrogen Isotopes ◽

Full Range ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Accumulation Rates ◽

Sea Levels ◽

Antarctic Snow ◽

Parallel Reconstruction

Precise Antarctic snow accumulation estimates are needed to understand past and future changes in global sea levels, but standard reconstructions using water isotopes suffer from competing isotopic effects external to accumulation. We present here an alternative accumulation proxy based on the post-depositional photolytic fractionation of nitrogen isotopes (d15N) in nitrate. On the high plateau of East Antarctica, sunlight penetrating the uppermost snow layers converts snow-borne nitrate into nitrogen oxide gas that can be lost to the atmosphere. This nitrate loss favors 14NO3- over 15NO3-, and thus the d15N of nitrate remaining in the snow will steadily increase until the nitrate is eventually buried beneath the reach of light. Because the duration of time until burial is dependent upon the rate of net snow accumulation, sites with lower accumulation rates have a longer burial wait and thus higher d15N values. A linear relationship (r2 = 0.86) between d15N and net accumulation-1 is calculated from over 120 samples representing 105 sites spanning East Antarctica. These sites largely encompass the full range of snow accumulation rates observed in East Antarctica, from 25 kg m-2 yr-1 at deep interior sites to >400 kg m-2 yr-1 at near coastal sites. We apply this relationship as a transfer function to an Aurora Basin ice core to produce a 700-year record of accumulation changes. Our nitrate-based estimate compares very well with a parallel reconstruction for Aurora Basin that uses volcanic horizons and ice-penetrating radar. Continued improvements to our database may enable precise independent estimates of millennial-scale accumulation changes using deep ice cores such as EPICA Dome C and Beyond EPICA-Oldest Ice.

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Diatoms in Ice Cores, a new proxy for reconstructing past wind strength in the Amundsen-Bellingshausen Seas region, Antarctica

10.5194/egusphere-egu21-15893 ◽

2021 ◽

Author(s):

Dieter Tetzner ◽

Liz Thomas ◽

Claire Allen

Keyword(s):

Antarctic Peninsula ◽

Ice Cores ◽

Environmental Parameters ◽

Time Frame ◽

Regional Variability ◽

Atmospheric Circulation Patterns ◽

Surface Temperatures ◽

Circulation Patterns ◽

And Shifts ◽

Basal Melting

In the last decade, several efforts have been carried out to assess the causes of the current rapid recent warming measured on West Antarctica and Antarctic Peninsula. The increase in wind strength and shifts in atmospheric circulation patterns have shown to play a key role in driving the advection of warm air from mid-latitudes to high-latitudes. Winds are also responsible for driving surface melting in the ice shelves, enhancing the removal of surface snow, and for promoting basal melting through the upwelling of deep warm water. All these combined have shown to produce substantial effects on environmental parameters, such as sea surface temperatures, sea ice extension, air surface temperatures and precipitation.Even though winds are fundamental components of the climatic system, there is a lack of reliable long-term observational wind records in the region. This has hindered the ability to place the recent observed changes in the context of a longer time frame.In this work, we present annual and sub-annual records of marine diatoms preserved in a set of ice cores retrieved from the southern Antarctic Peninsula and Ellsworth Land region, Antarctica. The diatom abundance and species assemblages from these ice cores prove to represent the local/regional variability in wind strength and circulation patterns that influence the onshore northerly winds.&#160; The spatial distribution of these ice cores enabled to identify regional trends (coastal/inland) and to validate the proxy across the region. Our findings highlight the potential this novel proxy to produce an annual reconstruction of westerly winds in the Amundsen - Bellingshausen seas region.&#160;

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