Dependence of the isotopic composition of different precipitation types on air temperature in Central Antarctica

Water isotopes are key proxies to reconstruct past climatic conditions on our planet based on Antarctic ice core data. The accuracy of climate reconstructions depends on understanding the whole range of the processes involved in the formation of precipitation isotopic composition. The isotopic composition of precipitation in Central Antarctica has been studied in a number of works, but the difference between the isotopic composition of different types of precipitation has not yet been fully described.There are three main type of precipitation in Central Antarctica: snow, ice needles and hoar. The aim of this work is to establish the dependence of isotopic composition of different precipitation types on temperature. Precipitation samples were collected at Vostok station in Central Antarctica from 1998 to 2020 and further analyzed for δ18O and δD. For each precipitation event we have meteorological data, averaged over the time of precipitation fallout. Mean values of δD for each precipitation type were defined as follows: –444±6.5 ‰ for diamond dust, –480± 6 ‰ for hoar and –95±11 ‰ for snow. The seasonal variability of the temperature dependence of the isotopic composition was studied using the example of ice needles. According to our data, the dependence is insignificant in winter, but this needs to be confirmed by an extended dataset. The largest slope of the isotope-temperature dependence regression line is observed for the summer period and is equal to 5.34±3.11 ‰·°С–1, the autumn season has a slope of 2.1±1.3 ‰·°С–1, while for the spring period we do not have enough data for analysis. There is an insignificant difference in the slopes of the isotope-temperature dependence for different types of precipitation: 2.93±0.51 ‰·°С–1 for ice needles, 2.32±1.34 ‰·°С–1 for snow and 2.52±0.35 ‰·°С–1 for hoar. We studied the effect of blizzards on the isotopic composition of samples and concluded that one should avoid using data collected during a blizzard to study the differences in the formation of the isotopic signal for different types of precipitation.This work brings us closer to understanding how isotopic composition is formed in each type of precipitation and what information it provides. This will contribute to a more accurate interpretation of the isotope signal from ice cores.

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Archival processes of the water stable isotope signal in East Antarctic ice cores

10.5194/tc-2017-243 ◽

2017 ◽

Cited By ~ 1

Author(s):

Mathieu Casado ◽

Amaelle Landais ◽

Ghislain Picard ◽

Thomas Münch ◽

Thomas Laepple ◽

...

Keyword(s):

Isotopic Composition ◽

Climate Models ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Antarctic Plateau ◽

Surface Snow ◽

Rayleigh Distillation ◽

The Difference ◽

Ice Core Records

Abstract. The oldest ice core records are obtained from the East Antarctic plateau. Water isotopes records are key to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all the processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in Rayleigh distillation and isotope enabled climate models. However, a quantitative understanding of processes potentially altering the snow isotopic composition after the deposition is still missing. In low accumulation sites, such as those found in Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretation of isotopic composition. Here, we combine observations of isotopic composition in the vapour, the precipitation, the surface snow and the buried snow from Dome C, a deep ice core site on the East Antarctic Plateau. At the seasonal scale, we suggest a significant impact of metamorphism on surface snow isotopic signal compared to the initial precipitation signal. Particularly, in summer, exchanges of water molecules between vapour and snow are driven by the sublimation/condensation cycles at the diurnal scale. Using highly resolved isotopic composition profiles from pits in five Antarctic sites, we identify common patterns, despite different accumulation rates, which cannot be attributed to the seasonal variability of precipitation. Altogether, the difference in the signals observed in the precipitation, surface snow and buried snow isotopic composition constitute evidences of post-deposition processes affecting ice core records in low accumulation areas.

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Sequence of events at high resolution during deglaciations over the last 800ka from the EDC ice core

10.5194/egusphere-egu21-7850 ◽

2021 ◽

Author(s):

Antoine Grisart ◽

amaelle landais ◽

barbara stenni ◽

ilaria crotti ◽

valérie masson delmotte ◽

...

Keyword(s):

High Resolution ◽

Isotopic Composition ◽

Elemental Composition ◽

Water Cycle ◽

Atmospheric Oxygen ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Low Latitude ◽

Sequence Of Events

The EPICA Dome C (EDC) ice core has been drilled from 1996 to 2004. Its study revealed a unique 800 ka long continuous climatic record including 9 deglaciations. Ice cores contain numerous proxies in the ice and in the air trapped in bubbles (chronological constraints, greenhouse gases concentration, local temperature proxies, mid to low latitude climate proxies). Here, we focus on information provided by the isotopic (and elemental) composition of water and oxygen archived in both ice and gas matrix. On one hand, the water isotopic composition brings information on past temperatures and water cycle re-organizations:&#160;&#160; d18O or dD records past temperature, whereas the combination of d18O with dD or d17O provide information on the past water cycle organization through d-excess and 17O-excess linked to climatic conditions of the evaporative regions. On the other hand, the elemental composition of oxygen expressed in the O2/N2 ratio provides key information for orbital dating over the last 800 ka in complement with the isotopic composition of atmospheric oxygen (d18O of O2 or d18Oatm) which is related as well to the low latitude water cycle.In this study, we present new high resolution records of water isotopes (d18O, d-excess and 17O-excess) as well as high resolution measurements of O2/N2 and d18Oatm over the last 9 deglaciations on the EDC ice core. We first use the high resolution records of O2/N2 and d18Oatm to improve absolute dating constrain over the glacial terminations and discuss the link between orbital forcing and climate variations recorded in the EDC ice core. In a second part, we use d-excess, 17O-excess and d18Oatm to constrain the relative chronology of high vs low latitude climatic events at sub-millennial scale over past deglaciations.

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Archival processes of the water stable isotope signal in East Antarctic ice cores

The Cryosphere ◽

10.5194/tc-12-1745-2018 ◽

2018 ◽

Vol 12 (5) ◽

pp. 1745-1766 ◽

Cited By ~ 15

Author(s):

Mathieu Casado ◽

Amaelle Landais ◽

Ghislain Picard ◽

Thomas Münch ◽

Thomas Laepple ◽

...

Keyword(s):

Isotopic Composition ◽

Climate Models ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Antarctic Plateau ◽

Surface Snow ◽

Rayleigh Distillation ◽

Deposition Processes ◽

Ice Core Records

Abstract. The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation–condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

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Large-scale drivers of Caucasus climate variability in meteorological records and Mt Elbrus ice cores

10.5194/cp-2016-62 ◽

2016 ◽

Cited By ~ 1

Author(s):

Anna Kozachek ◽

Vladimir Mikhalenko ◽

Valérie Masson-Delmotte ◽

Alexey Ekaykin ◽

Patrick Ginot ◽

...

Keyword(s):

Isotopic Composition ◽

Large Scale ◽

Isotope Composition ◽

Accumulation Rate ◽

Meteorological Data ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

The Caucasus ◽

Precipitation Record

Abstract. A 181.2 m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt. Elbrus (43°20’53.9’’ N, 42°25’36.0’’ E; 5115 m a.s.l.) in the Caucasus, Russia, in 2009 (Mikhalenko et al., 2015). Here, we report on the results of the water stable isotope composition from this ice core in comparison with results from shallow ice cores. There is a distinct seasonal cycle of the isotopic composition which allowed dating by annual layer counting. Dating has been performed for the upper 126 m of the deep core combined with shallow cores data. The whole record covers one century from 2013 back to 1914. Due to the high accumulation rate (1380 mm w.e. per year) and limited melting we obtained the isotopic composition and accumulation rate records with seasonal resolution. These values were compared with available meteorological data from 13 weather stations in the region, and also with atmosphere circulation indices, back-trajectories calculations and GNIP data in order to decipher the drivers of accumulation and ice core isotopic composition in the Caucasus region. In the summer season the isotopic composition depends on the local temperature, while in winter, the atmospheric circulation is the predominant driver of the ice core isotopic composition. The snow accumulation rate correlates well with the precipitation rate in the region all year round, this made it possible to reconstruct and expand the precipitation record at the Caucasus highlands from 1914 till 1966 when the reliable meteorological observations of precipitation at high elevation began.

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Triple isotopic composition of oxygen in water and dioxygen during deglaciations recorded in the EPICA Dome C ice core to link climate, biosphere productivity and water cycle

10.5194/egusphere-egu2020-5961 ◽

2020 ◽

Author(s):

Amaelle Landais ◽

Ji-Woong Yang ◽

Nicolas Pasquier ◽

Antoine Grisart ◽

Margaux Brandon ◽

...

Keyword(s):

Isotopic Composition ◽

Hydrological Cycle ◽

Water Cycle ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Added Value ◽

Air Bubbles ◽

The Past

High precision measurements of triple isotopic composition of oxygen in water is a useful tool to infer the dynamic of past hydrological cycle when measured in ice core together with &#948;18O and &#948;D. In particular, the triple isotopic composition of oxygen in water provides information on the climatic conditions of the evaporative sources. In parallel, it has been shown that the triple isotopic composition of oxygen in the atmospheric dioxygen can be a useful tracer of the global biosphere productivity and hence reconstruct the dynamic of the global biosphere productivity in the past from measurements performed in the air bubbles. Measuring triple isotopic composition of oxygen both in the water and in the atmospheric dioxygen trapped in bubbles in ice cores is thus a strong added value to study the past variability of water cycle and biosphere productivity in parallel to climate change.Here, we first present new laboratory experiments performed in closed biological chambers to show how the triple isotopic composition of oxygen in atmospheric dioxygen can be used for quantification of the biosphere productivity with determination of fractionation coefficients. Then, we present new records of triple isotopic composition of oxygen in water and O2 trapped in bubbles from the EPICA Dome C ice core over the deglaciations of the last 800 ka.

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Archival of the water stable isotope signal in East Antarctic ice cores

10.5194/tc-2016-263 ◽

2016 ◽

Cited By ~ 6

Author(s):

Mathieu Casado ◽

Amaelle Landais ◽

Ghislain Picard ◽

Thomas Münch ◽

Thomas Laepple ◽

...

Keyword(s):

Isotopic Composition ◽

Climate Models ◽

Ice Core ◽

Ice Cores ◽

Climatic Conditions ◽

Antarctic Plateau ◽

Surface Snow ◽

Rayleigh Distillation ◽

Isotopic Signal ◽

Ice Core Records

Abstract. The oldest ice core records are obtained from the East Antarctic plateau. Water stable isotopes records are key for reconstructions of past climatic conditions both over the ice sheet and at the evaporation source. The accuracy of such climate reconstructions crucially depends on the knowledge of all the processes affecting the water vapour, precipitation and snow isotopic composition. Atmospheric fractionation processes are well understood and can be integrated in Rayleigh distillation and complex isotope enabled climate models. However, a comprehensive quantitative understanding of processes potentially altering the snow isotopic composition after the deposition is still missing, especially for exchanges between vapour and snow. In low accumulation sites such as found on the East Antarctic Plateau, these poorly constrained processes are especially likely to play a significant role. This limits the interpretation of isotopic composition from ice core records, specifically at short time scales. Here, we combine observations of isotopic composition in the vapour, the precipitation, the surface snow and the buried snow from various sites of the East Antarctic Plateau. At the seasonal scale, we highlight a significant impact of metamorphism on surface snow isotopic signal compared to the initial precipitation isotopic signal. In particular, in summer, exchanges of water molecules between vapour and snow are driven by the sublimation/condensation cycles at the diurnal scale. Using highly resolved isotopic composition profiles from pits in five East Antarctic sites, we identify a common 20 cm cycle which cannot be attributed to the seasonal variability of precipitation. Altogether, the smaller range of isotopic compositions observed in the buried and in the surface snow compared to the precipitation, and also the reduced slope between surface snow isotopic composition and temperature compared to precipitation, constitute evidences of post-deposition processes affecting the variability of the isotopic composition in the snow pack. To reproduce these processes in snow-models is crucial to understand the link between snow isotopic composition and climatic conditions and to improve the interpretation of isotopic composition as a paleoclimate proxy.

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On the relationship between stable isotopes and major impurity species as inferred from a two-dimensional firn sampling approach at EDML, East Antarctica

10.5194/egusphere-egu21-10362 ◽

2021 ◽

Author(s):

Thomas Münch ◽

Maria Hörhold ◽

Johannes Freitag ◽

Melanie Behrens ◽

Thomas Laepple

Keyword(s):

Isotopic Composition ◽

Interannual Variability ◽

Ice Core ◽

Ice Cores ◽

Temperature Changes ◽

Impurity Species ◽

Intermittent Precipitation ◽

Ice Core Record ◽

Stable Oxygen ◽

Atmospheric Variations

Ice cores constitute a major palaeoclimate archive by recording, among many others, the atmospheric variations of stable oxygen and hydrogen isotopic composition of water and of soluble ionic impurities. While impurities are used as proxies for, e.g., variations in sea ice, marine biological activity and volcanism, stable isotope records are the main source of information for the reconstruction of polar temperature changes.However, such reconstruction efforts are complicated by the fact that temperature is by far not the only driver of isotopic composition changes. A single isotopic ice-core record will comprise variations caused by a multitude of processes, from variable atmospheric circulation and moisture pathways to the intermittency of precipitation and finally to the mixing and re-location of surface snow by wind drift (stratigraphic noise). Under the assumption that specific trace components are originally deposited with the precipitated snow and its isotopic composition, the retrieved impurity records should display a similar spatial and seasonal to interannual variability as the isotope records, caused by local stratigraphic noise as well as the time-variable and intermittent precipitation patterns, respectively.In this contribution, we investigate the possible relationship between isotope and impurity data at the East Antarctic low-accumulation site EDML. We sampled and analysed isotopic composition and major impurity species on a four metre deep and 50&#160;metre long trench. This enables us (1) to study the spatial (horizontal times vertical) relationship in the data, and (2) to analyse and compare the seasonal and interannual variability after removing the strong contribution of local stratigraphic noise. By this, the study improves our understanding of the depositional mechanisms that play an important role for the formation of ice-core records, and it offers to investigate the potential of using impurities to correct isotopic variability in order to improve temperature reconstructions.

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New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr

Climate of the Past ◽

10.5194/cp-3-527-2007 ◽

2007 ◽

Vol 3 (3) ◽

pp. 527-540 ◽

Cited By ~ 78

Author(s):

L. Loulergue ◽

F. Parrenin ◽

T. Blunier ◽

J.-M. Barnola ◽

R. Spahni ◽

...

Keyword(s):

Ice Core ◽

Phase Relationship ◽

Ice Cores ◽

Climatic Conditions ◽

Ice Age ◽

Age Difference ◽

Last Deglaciation ◽

Last Glacial Period ◽

Polar Ice Sheets ◽

Dronning Maud Land

Abstract. Gas is trapped in polar ice sheets at ~50–120 m below the surface and is therefore younger than the surrounding ice. Firn densification models are used to evaluate this ice age-gas age difference (Δage) in the past. However, such models need to be validated by data, in particular for periods colder than present day on the East Antarctic plateau. Here we bring new constraints to test a firn densification model applied to the EPICA Dome C (EDC) site for the last 50 kyr, by linking the EDC ice core to the EPICA Dronning Maud Land (EDML) ice core, both in the ice phase (using volcanic horizons) and in the gas phase (using rapid methane variations). We also use the structured 10Be peak, occurring 41 kyr before present (BP) and due to the low geomagnetic field associated with the Laschamp event, to experimentally estimate the Δage during this event. Our results seem to reveal an overestimate of the Δage by the firn densification model during the last glacial period at EDC. Tests with different accumulation rates and temperature scenarios do not entirely resolve this discrepancy. Although the exact reasons for the Δage overestimate at the two EPICA sites remain unknown at this stage, we conclude that current densification model simulations have deficits under glacial climatic conditions. Whatever the cause of the Δage overestimate, our finding suggests that the phase relationship between CO2 and EDC temperature previously inferred for the start of the last deglaciation (lag of CO2 by 800±600 yr) seems to be overestimated.

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Climatic and atmospheric circulation pattern variability from ice-core isotope/geochemistry records (Altai, Tien Shan and Tibet)

Annals of Glaciology ◽

10.3189/172756406781812078 ◽

2006 ◽

Vol 43 ◽

pp. 49-60 ◽

Cited By ~ 87

Author(s):

Vladimir B. Aizen ◽

Elena M. Aizen ◽

Daniel R. Joswiak ◽

Koji Fujita ◽

Nozomu Takeuchi ◽

...

Keyword(s):

Air Temperature ◽

Isotope Geochemistry ◽

Eastern Mediterranean ◽

Meteorological Data ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Tien Shan ◽

Synoptic Climatology ◽

The Tibetan Plateau

AbstractSeveral firn/ice cores were recovered from the Siberian Altai (Belukha plateau), central Tien Shan (Inilchek glacier) and the Tibetan Plateau (Zuoqiupu glacier, Bomi) from 1998 to 2003. The comparison analyses of stable-isotope/geochemistry records obtained from these firn/ice cores identified the physical links controlling the climate-related signals at the seasonal-scale variability. The core data related to physical stratigraphy, meteorology and synoptic atmospheric dynamics were the basis for calibration, validation and clustering of the relationships between the firn-/ice-core isotope/ geochemistry and snow accumulation, air temperature and precipitation origin. The mean annual accumulation (in water equivalent) was 106 gcm−2 a−1 at Inilchek glacier, 69 gcm−2 a−1 at Belukha and 196 g cm−2 a−1 at Zuoqiupu. The slopes in regression lines between the δ18O ice-core records and air temperature were found to be positive for the Tien Shan and Altai glaciers and negative for southeastern Tibet, where heavy amounts of isotopically depleted precipitation occur during summer monsoons. The technique of coupling synoptic climatology and meteorological data with δ18O and d-excess in firn-core records was developed to determine climate-related signals and to identify the origin of moisture. In Altai, two-thirds of accumulation from 1984 to 2001 was formed from oceanic precipitation, and the rest of the precipitation was recycled over Aral–Caspian sources. In the Tien Shan, 87% of snow accumulation forms by precipitation originating from the Aral–Caspian closed basin, the eastern Mediterranean and Black Seas, and 13% from the North Atlantic.

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Spatial variability of surface snow isotopic composition on the East Antarctic Plateau and implications for climate reconstructions

10.5194/egusphere-egu2020-13653 ◽

2020 ◽

Author(s):

Maria Hörhold ◽

Alexander Weinhart ◽

Sepp Kipfstuhl ◽

Johannes Freitag ◽

Georgia Micha ◽

...

Keyword(s):

Isotopic Composition ◽

Ice Core ◽

Empirical Relationship ◽

Ice Cores ◽

Stable Water Isotopes ◽

Antarctic Plateau ◽

Mean Temperature ◽

Spatial Coverage ◽

Surface Snow ◽

Relationship Of

The reconstruction of past temperatures based on ice core records relies on the quantitative but empirical relationship of stable water isotopes and annual mean temperature. However, its relation varies through space and time. On the East Antarctic Plateau, temperature reconstructions from ice cores are poorly constrained or even fail on decadal and smaller time scales. The observed discrepancy between annual mean temperature and isotopic composition partly relies on surface processes altering the signal after deposition but also, to a great deal, on spatially coherent processes prior to or during deposition. However, spatial coverage over larger areas on the East Antarctic Plateau is challenging. We here present in-situ measurements of the isotopic composition of surface snow with unprecedented statistical quality and coverage. 1m surface snow profiles were collected during an overland traverse between Kohnen station and Plateau Station, covering a 1200km long transect. We explore regional differences of the temperature-isotope relationship and discuss possible mechanisms affecting the isotopic composition in areas with accumulation rates lower than 60mmWEa^-1.

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