Seasonal variations of accumulation and the isotope record in ice cores: a study with surface snow samples and firn cores from Neumayer station, Antarctica

AbstractAt the German wintering base Neumayer, an intensive glacio-meteorological programme has been carried out during the last two decades. A complete meteorological dataset and data from surface snow samples, snow pits, firn cores and weekly accumulation measurements from a stake array are available. We first investigated the attenuation of the seasonal δ18O signal due to water-vapour diffusion in the snowpack. A comparison of surface snow samples and firn cores of different ages shows that only one-third of the seasonal δ18O signal of the surface snow samples remains in the cores after the first year. No further significant change in the amplitude of the seasonal δ18O signal is found later. Changes in the seasonal distribution of accumulation can lead to a bias in ice-core properties. This is studied on a short time-scale, using high-time-resolution data of accumulation, stable-isotope ratios and air temperature. Mean annual δ18O values from firn cores are not well correlated to annual mean air temperatures. However, the correlation is improved considerably by calculating an annual mean air temperature using monthly mean temperatures weighted by monthly accumulation. At Neumayer, it is mainly the cyclonic activity in late winter/early spring that determines whether and how the core data are biased.

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Ranges of moisture-source temperature estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles

Climate of the Past ◽

10.5194/cp-8-1109-2012 ◽

2012 ◽

Vol 8 (3) ◽

pp. 1109-1125 ◽

Cited By ~ 75

Author(s):

R. Uemura ◽

V. Masson-Delmotte ◽

J. Jouzel ◽

A. Landais ◽

H. Motoyama ◽

...

Keyword(s):

Air Temperature ◽

Ice Core ◽

Ice Cores ◽

Regression Equations ◽

Temperature Changes ◽

Source Temperature ◽

Moisture Source ◽

Isotopic Model ◽

Temperature Proxy ◽

Coefficient Of Regression

Abstract. A single isotope ratio (δD or δ18O) of water is widely used as an air-temperature proxy in Antarctic ice core records. These isotope ratios, however, do not solely depend on air-temperature but also on the extent of distillation of heavy isotopes out of atmospheric water vapor from an oceanic moisture source to a precipitation site. The temperature changes at the oceanic moisture source (Δ Tsource) and at the precipitation site (Δ Tsite) can be retrieved by using deuterium-excess (d) data. A new d record from Dome Fuji, Antarctica spanning the past 360 000 yr is presented and compared with records from Vostok and EPICA Dome C ice cores. In previous studies, to retrieve Δ Tsource and Δ Tsite information, different linear regression equations were proposed using theoretical isotope distillation models. A major source of uncertainty lies in the coefficient of regression, βsite which is related to the sensitivity of d to Δ Tsite. We show that different ranges of temperature and selections of isotopic model outputs may increase the value of βsite by more than a factor of two. To explore the impacts of this coefficient on reconstructed temperatures, we apply for the first time the exact same methodology to the isotope records from the three Antarctica ice cores. We show that uncertainties in the βsite coefficient strongly affect (i) the glacial–interglacial magnitude of Δ Tsource; (ii) the imprint of obliquity in Δ Tsource and in the site-source temperature gradient. By contrast, we highlight the robustness of Δ Tsite reconstruction using water isotopes records.

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Possible Causes of the Variation in Microparticle Concentration in an Ice Core from Mizuho Station, Antarctica

Annals of Glaciology ◽

10.3189/s0260305500002615 ◽

1982 ◽

Vol 3 ◽

pp. 107-112 ◽

Cited By ~ 2

Author(s):

Yoshiyuki Fujii ◽

Tetsuo Ohata

Keyword(s):

Annual Cycle ◽

Arid Regions ◽

Annual Variation ◽

Ice Core ◽

Ice Cores ◽

Layer Formation ◽

Snow Layer ◽

Discontinuous Surface ◽

Surface Snow ◽

Surface Layer Formation

Variation of the microparticle concentration in an ice core from Mizuho station, East Antarctica, does not show the annual cycle that has been demonstrated for ice cores from Antarctica and Greenland by other authors. Possible reasons for the lack of a annual cycle are considered and two causes are suggested. (1) Semi-annual variation of microparticle concentration as observed in drift-snow. The low particle concentration in March and in August to October is not due to minor particle transport, but to the dilution of microparticles transported mainly from arid regions in the southern hemisphere through the troposphere by falling snow. (2) Discontinuous surface-layer formation. A seasonal or an annual sequence of the variation in microparticle concentration in surface snow layers may be interrupted by the absence of surface snow-layer formation.

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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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What controls the isotopic composition of Greenland surface snow?

Climate of the Past ◽

10.5194/cp-10-377-2014 ◽

2014 ◽

Vol 10 (1) ◽

pp. 377-392 ◽

Cited By ~ 82

Author(s):

H. C. Steen-Larsen ◽

V. Masson-Delmotte ◽

M. Hirabayashi ◽

R. Winkler ◽

K. Satow ◽

...

Keyword(s):

Water Vapor ◽

Isotopic Composition ◽

Air Temperature ◽

Ice Core ◽

Snow Surface ◽

Atmospheric Models ◽

Near Surface ◽

Core Data ◽

Surface Snow ◽

Precipitation Events

Abstract. Water stable isotopes in Greenland ice core data provide key paleoclimatic information, and have been compared with precipitation isotopic composition simulated by isotopically enabled atmospheric models. However, post-depositional processes linked with snow metamorphism remain poorly documented. For this purpose, monitoring of the isotopic composition (δ18O, δD) of near-surface water vapor, precipitation and samples of the top (0.5 cm) snow surface has been conducted during two summers (2011–2012) at NEEM, NW Greenland. The samples also include a subset of 17O-excess measurements over 4 days, and the measurements span the 2012 Greenland heat wave. Our observations are consistent with calculations assuming isotopic equilibrium between surface snow and water vapor. We observe a strong correlation between near-surface vapor δ18O and air temperature (0.85 ± 0.11‰ °C−1 (R = 0.76) for 2012). The correlation with air temperature is not observed in precipitation data or surface snow data. Deuterium excess (d-excess) is strongly anti-correlated with δ18O with a stronger slope for vapor than for precipitation and snow surface data. During nine 1–5-day periods between precipitation events, our data demonstrate parallel changes of δ18O and d-excess in surface snow and near-surface vapor. The changes in δ18O of the vapor are similar or larger than those of the snow δ18O. It is estimated using the CROCUS snow model that 6 to 20% of the surface snow mass is exchanged with the atmosphere. In our data, the sign of surface snow isotopic changes is not related to the sign or magnitude of sublimation or deposition. Comparisons with atmospheric models show that day-to-day variations in near-surface vapor isotopic composition are driven by synoptic variations and changes in air mass trajectories and distillation histories. We suggest that, in between precipitation events, changes in the surface snow isotopic composition are driven by these changes in near-surface vapor isotopic composition. This is consistent with an estimated 60% mass turnover of surface snow per day driven by snow recrystallization processes under NEEM summer surface snow temperature gradients. Our findings have implications for ice core data interpretation and model–data comparisons, and call for further process studies.

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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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Microfluidic device for continuous-flow analysis of organics in oldest ice

10.5194/egusphere-egu2020-19976 ◽

2020 ◽

Author(s):

Daniele FIlippi ◽

Chiara Giorio

Keyword(s):

Time Resolution ◽

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Core Sample ◽

High Time ◽

High Time Resolution ◽

Continuous Analysis ◽

Climate History ◽

History Of

The Beyond EPICA Oldest Ice (BEOI) project will drill an ice core dating back to 1.5 million-years (1.5 Myr) ago. This ice core is of particular interest to the scientific community as it will be the only one covering the climate history of the Mid Pleistocene Transition, when glacial-interglacial cycles changed from a 40 Kyr to 100 Kyr cyclicity, and for which causes are not well understood currently. Obtaining useful climatic information beyond 800 Kyr represents an analytical challenge due to the fact that the deepest section of the ice core is very compact and the amount of sample available is very low.Current analytical methods for the determination of organics in ice are characterized by a large number of steps that requires large amounts of sample for a single analysis. This results in the loss of the high time resolution desired from ice cores which is particularly problematic for deeper (i.e. older) records where the ice is more compact.This work aims at combining the growing field of microfluidics with improvements to conventional mass spectrometry to allow for continuous analysis of organics in ice cores, melted in continuous on a melting-head. In fact, microfluidic is a powerful technology in which, only a small amount of liquid (10-9-10-18 liters) is manipulated and controlled with an extremely high precision. The method invokes a three-step process: (1) the melted ice core sample is sent to a nebulizer to produce aerosol, then (2) the aerosol is dried to remove water content and concentrate the sample, and (3) the aerosol is sent to a mass spectrometer for continuous analysis through a modified electrospray ionization (ESI) probe.This novel system, once operational, can be applied to a range of ice cores but is especially useful for older ice cores given the stratification of deeper segments. It will allow the research community to measure organic compounds with a high time resolution, even in the oldest of ice, to retrieve paleoclimatic information that would otherwise be lost using traditional methods.

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Air–snow transfer of nitrate on the East Antarctic Plateau – Part 2: An isotopic model for the interpretation of deep ice-core records

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-12079-2015 ◽

2015 ◽

Vol 15 (20) ◽

pp. 12079-12113 ◽

Cited By ~ 17

Author(s):

J. Erbland ◽

J. Savarino ◽

S. Morin ◽

J. L. France ◽

M. M. Frey ◽

...

Keyword(s):

Mass Fraction ◽

Ice Core ◽

Ice Cores ◽

Reactive Nitrogen ◽

Antarctic Plateau ◽

Surface Snow ◽

Rate Building ◽

The Antarctic ◽

The Impact ◽

Ice Core Records

Abstract. Unraveling the modern budget of reactive nitrogen on the Antarctic Plateau is critical for the interpretation of ice-core records of nitrate. This requires accounting for nitrate recycling processes occurring in near-surface snow and the overlying atmospheric boundary layer. Not only concentration measurements but also isotopic ratios of nitrogen and oxygen in nitrate provide constraints on the processes at play. However, due to the large number of intertwined chemical and physical phenomena involved, numerical modeling is required to test hypotheses in a quantitative manner. Here we introduce the model TRANSITS (TRansfer of Atmospheric Nitrate Stable Isotopes To the Snow), a novel conceptual, multi-layer and one-dimensional model representing the impact of processes operating on nitrate at the air–snow interface on the East Antarctic Plateau, in terms of concentrations (mass fraction) and nitrogen (δ15N) and oxygen isotopic composition (17O excess, Δ17O) in nitrate. At the air–snow interface at Dome C (DC; 75° 06' S, 123° 19' E), the model reproduces well the values of δ15N in atmospheric and surface snow (skin layer) nitrate as well as in the δ15N profile in DC snow, including the observed extraordinary high positive values (around +300 ‰) below 2 cm. The model also captures the observed variability in nitrate mass fraction in the snow. While oxygen data are qualitatively reproduced at the air–snow interface at DC and in East Antarctica, the simulated Δ17O values underestimate the observed Δ17O values by several per mill. This is explained by the simplifications made in the description of the atmospheric cycling and oxidation of NO2 as well as by our lack of understanding of the NOx chemistry at Dome C. The model reproduces well the sensitivity of δ15N, Δ17O and the apparent fractionation constants (15&varepsilon;app, 17Eapp) to the snow accumulation rate. Building on this development, we propose a framework for the interpretation of nitrate records measured from ice cores. Measurement of nitrate mass fractions and δ15N in the nitrate archived in an ice core may be used to derive information about past variations in the total ozone column and/or the primary inputs of nitrate above Antarctica as well as in nitrate trapping efficiency (defined as the ratio between the archived nitrate flux and the primary nitrate input flux). The Δ17O of nitrate could then be corrected from the impact of cage recombination effects associated with the photolysis of nitrate in snow. Past changes in the relative contributions of the Δ17O in the primary inputs of nitrate and the Δ17O in the locally cycled NO2 and that inherited from the additional O atom in the oxidation of NO2 could then be determined. Therefore, information about the past variations in the local and long-range processes operating on reactive nitrogen species could be obtained from ice cores collected in low-accumulation regions such as the Antarctic Plateau.

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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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Climatological significance of δ18 O in precipitation and ice cores: a case study at the head of the Ürümqi river, Tien Shan, China

Journal of Glaciology ◽

10.3189/s0022143000001374 ◽

1999 ◽

Vol 45 (151) ◽

pp. 517-523

Author(s):

Hou Shugui ◽

Qin Dahe ◽

Paul A. Mayewski ◽

Yang Qinzhao ◽

Ren Jiawen ◽

...

Keyword(s):

Air Temperature ◽

Ice Core ◽

Sampling Site ◽

Surface Air Temperature ◽

Ice Cores ◽

Tien Shan ◽

Condensation Temperature ◽

Oxygen Isotope Ratios ◽

Stable Oxygen ◽

The Relationship

AbstractStable-oxygen-isotope ratios (δ18O) of precipitation and ice-core samples collected from the headwaters of the Urümqi river, Tien Shan, China, were used to test the relationship between δ18O and contemporaneous surface air temperature (Ta). A strong temporal relationship is found between δ18O in precipitation and Ta, particularly for the monthly averages which remove synoptic-scale influences such as changes in condensation level, condensation temperature and moisture sources ( Yao and others, 1996). Linear fits as high as 0.95‰° C-1 for precipitation events and 1.23‰° C-1 for monthly averages are found. Although the δ18O amplitude in ice cores drilled at the nearby Ürümqi glacier No.1(~2 km from the precipitation sampling site) decreased dramatically compared to the precipitation samples, the ice-core records of annually averaged δ18 are still positively correlated with contemporaneous air temperature, especially summer air temperature, at the nearby Daxigou meteorological station. Nevertheless, the relationship between the ice-core δ18O records and contemporaneous air temperature is less significant than that for the precipitation samples due to depositional and post-depositional modification processes, which are highlighted by the successive snow-pit δ18O profiles from the Ürümqi glacier No.1. Our results might extend the application of high-altitude and subtropical ice-core δ18O —Ta records for paleoclimate reconstruction.

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Climatological significance of δ18 O in precipitation and ice cores: a case study at the head of the Ürümqi river, Tien Shan, China

Journal of Glaciology ◽

10.1017/s0022143000001374 ◽

1999 ◽

Vol 45 (151) ◽

pp. 517-523 ◽

Cited By ~ 13

Author(s):

Hou Shugui ◽

Qin Dahe ◽

Paul A. Mayewski ◽

Yang Qinzhao ◽

Ren Jiawen ◽

...

Keyword(s):

Air Temperature ◽

Ice Core ◽

Sampling Site ◽

Surface Air Temperature ◽

Ice Cores ◽

Tien Shan ◽

Condensation Temperature ◽

Oxygen Isotope Ratios ◽

Stable Oxygen ◽

The Relationship

AbstractStable-oxygen-isotope ratios(δ18O)of precipitation and ice-core samples collected from the headwaters of the Urümqi river, Tien Shan, China, were used to test the relationship betweenδ18Oand contemporaneous surface air temperature (Ta). A strong temporal relationship is found betweenδ18Oin precipitation andTa,particularly for the monthly averages which remove synoptic-scale influences such as changes in condensation level, condensation temperature and moisture sources ( Yao and others, 1996). Linear fits as high as 0.95‰° C-1for precipitation events and 1.23‰° C-1for monthly averages are found. Although theδ18O amplitude in ice cores drilled at the nearby Ürümqi glacier No.1(~2 km from the precipitation sampling site) decreased dramatically compared to the precipitation samples, the ice-core records of annually averagedδ18are still positively correlated with contemporaneous air temperature, especially summer air temperature, at the nearby Daxigou meteorological station. Nevertheless, the relationship between the ice-coreδ18Orecords and contemporaneous air temperature is less significant than that for the precipitation samples due to depositional and post-depositional modification processes, which are highlighted by the successive snow-pitδ18Oprofiles from the Ürümqi glacier No.1. Our results might extend the application of high-altitude and subtropical ice-coreδ18O—Tarecords for paleoclimate reconstruction.

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