On the occurrence of annual layers in Dome Fuji ice core early Holocene ice

Abstract. Whereas ice cores from high-accumulation sites in coastal Antarctica clearly demonstrate annual layering, it is debated whether a seasonal signal is also preserved in ice cores from lower-accumulation sites further inland and particularly on the East Antarctic Plateau. In this study, we examine 5 m of early Holocene ice from the Dome Fuji (DF) ice core at a high temporal resolution by continuous flow analysis. The ice was continuously analysed for concentrations of dust, sodium, ammonium, liquid conductivity, and water isotopic composition. Furthermore, a dielectric profiling was performed on the solid ice. In most of the analysed ice, the multi-parameter impurity data set appears to resolve the seasonal variability although the identification of annual layers is not always unambiguous. The study thus provides information on the snow accumulation process in central East Antarctica. A layer counting based on the same principles as those previously applied to the NGRIP (North Greenland Ice core Project) and the Antarctic EPICA (European Project for Ice Coring in Antarctica) Dronning Maud Land (EDML) ice cores leads to a mean annual layer thickness for the DF ice of 3.0 ± 0.3 cm that compares well to existing estimates. The measured DF section is linked to the EDML ice core through a characteristic pattern of three significant acidity peaks that are present in both cores. The corresponding section of the EDML ice core has recently been dated by annual layer counting and the number of years identified independently in the two cores agree within error estimates. We therefore conclude that, to first order, the annual signal is preserved in this section of the DF core. This case study demonstrates the feasibility of determining annually deposited strata on the central East Antarctic Plateau. It also opens the possibility of resolving annual layers in the Eemian section of Antarctic ice cores where the accumulation is estimated to have been greater than in the Holocene.

Download Full-text

On the occurrence of annual layers in Dome Fuji ice core early Holocene ice

Climate of the Past Discussions ◽

10.5194/cpd-11-805-2015 ◽

2015 ◽

Vol 11 (2) ◽

pp. 805-830

Author(s):

A. Svensson ◽

S. Fujita ◽

M. Bigler ◽

M. Braun ◽

R. Dallmayr ◽

...

Keyword(s):

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Early Holocene ◽

High Temporal Resolution ◽

High Accumulation ◽

Antarctic Plateau ◽

Annual Layer ◽

Dronning Maud Land ◽

Seasonal Signal

Abstract. Whereas ice cores from high accumulation sites in coastal Antarctica clearly demonstrate annual layering, it is debated whether a seasonal signal is also preserved in ice cores from lower accumulation sites further inland and particularly on the East Antarctic Plateau. In this study, we examine five metres of early Holocene ice from the Dome Fuji (DF) ice core in high temporal resolution by continuous flow analysis. The ice was continuously analyzed for concentrations of dust, sodium, ammonium, liquid conductivity, and water isotopic composition. Furthermore, a dielectric profiling was performed on the solid ice. In most of the analyzed ice, the multi-parameter impurity dataset appears to resolve the seasonal variability although the identification of annual layers is not always unambiguous. A layer counting based on the same principles as those previously applied to the Greenland NGRIP and the Antarctic EPICA Dronning Maud Land (EDML) ice cores leads to a mean annual layer thickness for the DF ice of 3.0 ± 0.3 cm that compares well to existing estimates. The measured DF section is linked to the EDML ice core through a characteristic pattern of three significant acidity peaks that are present in both cores. The corresponding section of the EDML ice core has recently been dated by annual layer counting and the number of years identified independently in the two cores agree within error estimates. We therefore conclude that, to first order, the annual signal is preserved in this section of the DF core. This case study demonstrates the feasibility of determining annually deposited strata on the central Eastern Antarctic Plateau. It also opens the possibility of resolving annual layers in the Eemian section of the DF ice core where the accumulation is estimated to have been greater than in the Holocene.

Download Full-text

The WAIS Divide deep ice core WD2014 chronology – Part 1: Methane synchronization (68–31 ka BP) and the gas age–ice age difference

Climate of the Past ◽

10.5194/cp-11-153-2015 ◽

2015 ◽

Vol 11 (2) ◽

pp. 153-173 ◽

Cited By ~ 101

Author(s):

C. Buizert ◽

K. M. Cuffey ◽

J. P. Severinghaus ◽

D. Baggenstos ◽

T. J. Fudge ◽

...

Keyword(s):

Ice Core ◽

Impurity Content ◽

Ice Cores ◽

Ice Age ◽

Age Difference ◽

Atmospheric Methane ◽

High Accumulation ◽

Data Set ◽

Annual Layer ◽

West Antarctic

Abstract. The West Antarctic Ice Sheet Divide (WAIS Divide, WD) ice core is a newly drilled, high-accumulation deep ice core that provides Antarctic climate records of the past ∼68 ka at unprecedented temporal resolution. The upper 2850 m (back to 31.2 ka BP) have been dated using annual-layer counting. Here we present a chronology for the deep part of the core (67.8–31.2 ka BP), which is based on stratigraphic matching to annual-layer-counted Greenland ice cores using globally well-mixed atmospheric methane. We calculate the WD gas age–ice age difference (Δage) using a combination of firn densification modeling, ice-flow modeling, and a data set of δ15N-N2, a proxy for past firn column thickness. The largest Δage at WD occurs during the Last Glacial Maximum, and is 525 ± 120 years. Internally consistent solutions can be found only when assuming little to no influence of impurity content on densification rates, contrary to a recently proposed hypothesis. We synchronize the WD chronology to a linearly scaled version of the layer-counted Greenland Ice Core Chronology (GICC05), which brings the age of Dansgaard–Oeschger (DO) events into agreement with the U/Th absolutely dated Hulu Cave speleothem record. The small Δage at WD provides valuable opportunities to investigate the timing of atmospheric greenhouse gas variations relative to Antarctic climate, as well as the interhemispheric phasing of the "bipolar seesaw".

Download Full-text

Local scale depositional processes of surface snow on the Greenland ice sheet

10.5194/tc-2021-36 ◽

2021 ◽

Author(s):

Alexandra M. Zuhr ◽

Thomas Münch ◽

Hans Christian Steen-Larsen ◽

Maria Hörhold ◽

Thomas Laepple

Keyword(s):

Spatial Scales ◽

Ice Core ◽

Negative Relationship ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Snow Accumulation ◽

Data Set ◽

Climate Signal ◽

Depositional Processes ◽

Snow Deposition

Abstract. Ice cores from polar ice sheets and glaciers are an important climate archive. Snow layers, consecutively deposited and buried, contain climatic information of the time of their formation. However, particularly low-accumulation areas are characterised by temporally intermittent precipitation, which can be further re-distributed after initial deposition. Therefore, the local conditions of accumulation at an ice core site influence the quantity and quality of the recorded climate signal in proxy records. Local surface features at different spatial scales further affect the signal imprint. This study therefore aims to characterise the local accumulation patterns and the evolution of the snow height to describe the contribution of snow (re-)deposition to noise in climate records from ice cores. By using a photogrammetry Structure-from-Motion approach, we generated near-daily elevation models of the snow surface for a 195 m2 area in the vicinity of the deep drilling site of the East Greenland Ice Core Project in northeast Greenland. Based on the snow height information we derived snow height changes on a day-to-day basis throughout our observation period from May to August 2018. Specifically, the average snow height increased by ~11 cm. The spatial and temporal data set allowed an investigation of snow deposition versus depositional modifications. We observed irregular snow deposition, erosion, and the re-distribution of snow, which caused uneven snow accumulation patterns, a removal of more than 60 % of the deposited snow, and a negative relationship between the initial snow height and the amount of accumulated snow. Furthermore, the surface roughness decreased from 4 to 2 cm throughout the spring and summer season at our study site. Finally, our study further shows that our method has several advantages over previous approaches, making it possible to demonstrate the importance of accumulation intermittency, and the potential influences of depositional processes on proxy signals in snow and ice.

Download Full-text

A portable Lightweight In Situ Analysis (LISA) box for ice and snow analysis

10.5194/tc-2021-51 ◽

2021 ◽

Author(s):

Helle Astrid Kjær ◽

Lisa Lolk Hauge ◽

Marius Simonsen ◽

Zurine Yoldi ◽

Iben Koldtoft ◽

...

Keyword(s):

Ice Core ◽

Flow Analysis ◽

Snow Accumulation ◽

Field Conditions ◽

In Situ Analysis ◽

Transport Costs ◽

Water Conductivity ◽

Annual Layer ◽

Drilling Site

Abstract. Polar researchers spend enormous costs transporting snow and ice samples to home laboratories for simple analyses in order to constrain annual layer thicknesses and identifying accumulation rates of specific sites. It is well known that depositional noise, incurred from wind drifts, seasonally-biased deposition, melt layers and more, can influence individual snow and firn records and that multiple cores are required to produce statistically robust time series. Thus at many sites core samples are measured in the field for densification, but the annual accumulation and the content of chemical impurities are often represented by just one core to reduce transport costs. We have developed a portable Light weight in Situ Analysis (LISA) box for ice, firn and snow analysis capable of constraining annual layers through the continuous flow analysis of melt water conductivity and peroxide under field conditions. The box can run using a small gasoline-generator and weighs less than 50 kg. The LISA box was tested under field conditions at the deep ice core drilling site EastGRIP in Northern Greenland. Analysis of the top 2 metres of snow from 7 sites in Northern Greenland (Figure 1) allowed the reconstruction of regional snow accumulation patterns for the period 2015–2019.

Download Full-text

New LA-ICP-MS cryocell and calibration technique for sub-millimeter analysis of ice cores

Journal of Glaciology ◽

10.3189/2015jog14j139 ◽

2015 ◽

Vol 61 (226) ◽

pp. 233-242 ◽

Cited By ~ 22

Author(s):

Sharon B. Sneed ◽

Paul A. Mayewski ◽

W.G. Sayre ◽

Michael J. Handley ◽

Andrei V. Kurbatov ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Chemical Constituents ◽

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Calibration Technique ◽

Inductively Coupled ◽

Annual Layer ◽

Icp Ms ◽

Plasma Mass Spectrometry

AbstractIce cores provide a robust reconstruction of past climate. However, development of timescales by annual-layer counting, essential to detailed climate reconstruction and interpretation, on ice cores collected at low-accumulation sites or in regions of compressed ice, is problematic due to closely spaced layers. Ice-core analysis by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) provides sub-millimeter-scale sampling resolution (on the order of 100 μm in this study) and the low detection limits (ng L−1) necessary to measure the chemical constituents preserved in ice cores. We present a newly developed cryocell that can hold a 1 m long section of ice core, and an alternative strategy for calibration. Using ice-core samples from central Greenland, we demonstrate the repeatability of multiple ablation passes, highlight the improved sampling resolution, verify the calibration technique and identify annual layers in the chemical profile in a deep section of an ice core where annual layers have not previously been identified using chemistry. In addition, using sections of cores from the Swiss/Italian Alps we illustrate the relationship between Ca, Na and Fe and particle concentration and conductivity, and validate the LA-ICP-MS Ca profile through a direct comparison with continuous flow analysis results.

Download Full-text

Local-scale deposition of surface snow on the Greenland ice sheet

The Cryosphere ◽

10.5194/tc-15-4873-2021 ◽

2021 ◽

Vol 15 (10) ◽

pp. 4873-4900

Author(s):

Alexandra M. Zuhr ◽

Thomas Münch ◽

Hans Christian Steen-Larsen ◽

Maria Hörhold ◽

Thomas Laepple

Keyword(s):

Structure From Motion ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Data Set ◽

Simple Method ◽

Climate Signal ◽

Depositional Processes ◽

Surface Snow ◽

Snow Deposition

Abstract. Ice cores from polar ice sheets and glaciers are an important climate archive. Snow layers, consecutively deposited and buried, contain climatic information from the time of their formation. However, particularly low-accumulation areas are characterised by temporally intermittent precipitation, which can be further redistributed after initial deposition, depending on the local surface features at different spatial scales. Therefore, the accumulation conditions at an ice core site influence the quantity and quality of the recorded climate signal in proxy records. This study aims to characterise the local accumulation patterns and the evolution of the snow height to describe the contribution of the snow (re-)deposition to the overall noise level in climate records from ice cores. To this end, we applied a structure-from-motion photogrammetry approach to generate near-daily elevation models of the surface snow for a 195 m2 area in the vicinity of the deep drilling site of the East Greenland Ice-core Project in northeast Greenland. Based on the snow height information we derive snow height changes on a day-to-day basis throughout our observation period from May to August 2018 and find an average snow height increase of ∼ 11 cm. The spatial and temporal data set also allows an investigation of snow deposition versus depositional modifications. We observe irregular snow deposition and erosion causing uneven snow accumulation patterns, a removal of more than 60 % of the deposited snow, and a negative relationship between the initial snow height and the amount of accumulated snow. Furthermore, the surface roughness decreased by approximately a factor of 2 throughout the spring and summer season at our study site. Finally, our study shows that structure from motion is a relatively simple method to demonstrate the potential influences of depositional processes on proxy signals in snow and ice.

Download Full-text

Snow Accumulation and Oxygen-Isotope Records at the Law Dome Summit, Antarctica (Abstract)

Annals of Glaciology ◽

10.3189/s0260305500006844 ◽

1988 ◽

Vol 11 ◽

pp. 220-220

Author(s):

V. I. Morgan

Keyword(s):

Oxygen Isotope ◽

Isotope Ratio ◽

Meteorological Data ◽

Ice Core ◽

Surface Profile ◽

Correlation Coefficients ◽

Ice Cores ◽

Snow Accumulation ◽

Annual Layer ◽

The Law

At the summit of Law Dome (66°44′S, 112°50′E) the annual snow accumulation is equivalent to 0.7 m of water, and seasonal cycles of oxygen-isotope ratio are preserved clearly in the firn. Isotope-ratio measurements on three 28 m deep ice cores taken 15 m apart near the summit show that although annual layer thicknesses are well correlated between the cores, the actual isotope values (even when averaged over several years’ accumulation) are poorly correlated.Since the three sites must obviously receive the same precipitation, the differences in isotope ratio imply that the amounts of the precipitation retained as accumulation from individual snow-falls throughout the year must vary. The large seasonal variation in isotope ratio then easily accounts for the offsets.In the Law Dome region, precipitation occurs mainly as a result of cyclonic activity in spring, winter and autumn. The stronger winds experienced at these times cause the snow to be formed into large dunes, which are the stable (although moving) surface configuration under these conditions. The movement of dunes by erosion on one face and deposition on the other causes the snow in them to be well mixed. Isotope measurements on a 0.7 m high dune on the inland ice cap showed that it was composed of “winter” snow, with an average isotope value of −28.2% and a range of only 1%. The harder underlying snow had values which varied between −24.2 and −27.4%.During periods of relatively calm or warm conditions the dunes become consolidated and their movement is greatly reduced. Further snow-falls then do not add accumulation to the top and up-wind side of the dunes but tend to fill them in on the down-wind side. In particular it is observed that for Law Dome the surface profile is quite rough in winter and spring, but the more gentle winds and light snow-falls experienced in summer produce a very smooth surface at the beginning of autumn, with all the surface hollows filled in.The ice-core isotope profiles confirm the evenness of the summer accumulation, compared to that of winter. Correlation coefficients are typically 0.26 for the winter minima and 0.65 for the summer peak in isotope ratio. This means that somewhat shorter averaging times can be used when compiling “climatic” records from isotope profiles if only the “summer” isotope values are used. This is useful in comparison of isotopic and meteorological data when only a limited time span is available.Apart from the short-term effects, which can be reduced as desired by longer averaging periods, these core studies also demonstrate how any process which can modulate the precipitation or accumulation will also affect the isotopic composition of the accumulated snow.

Download Full-text

Phase relationships between orbital forcing and the composition of air trapped in Antarctic ice cores

Climate of the Past ◽

10.5194/cp-12-729-2016 ◽

2016 ◽

Vol 12 (3) ◽

pp. 729-748 ◽

Cited By ~ 6

Author(s):

Lucie Bazin ◽

Amaelle Landais ◽

Emilie Capron ◽

Valérie Masson-Delmotte ◽

Catherine Ritz ◽

...

Keyword(s):

Ice Core ◽

Ice Cores ◽

Data Set ◽

Air Content ◽

Annual Layer ◽

Polar Ice Sheets ◽

Orbital Tuning ◽

Two Parameters ◽

First Time ◽

Mis 5

Abstract. Orbital tuning is central for ice core chronologies beyond annual layer counting, available back to 60 ka (i.e. thousands of years before 1950) for Greenland ice cores. While several complementary orbital tuning tools have recently been developed using δ18Oatm, δO2⁄N2 and air content with different orbital targets, quantifying their uncertainties remains a challenge. Indeed, the exact processes linking variations of these parameters, measured in the air trapped in ice, to their orbital targets are not yet fully understood. Here, we provide new series of δO2∕N2 and δ18Oatm data encompassing Marine Isotopic Stage (MIS) 5 (between 100 and 160 ka) and the oldest part (340–800 ka) of the East Antarctic EPICA Dome C (EDC) ice core. For the first time, the measurements over MIS 5 allow an inter-comparison of δO2∕N2 and δ18Oatm records from three East Antarctic ice core sites (EDC, Vostok and Dome F). This comparison highlights some site-specific δO2∕N2 variations. Such an observation, the evidence of a 100 ka periodicity in the δO2∕N2 signal and the difficulty to identify extrema and mid-slopes in δO2∕N2 increase the uncertainty associated with the use of δO2∕N2 as an orbital tuning tool, now calculated to be 3–4 ka. When combining records of δ18Oatm and δO2∕N2 from Vostok and EDC, we find a loss of orbital signature for these two parameters during periods of minimum eccentricity (∼ 400 ka, ∼ 720–800 ka). Our data set reveals a time-varying offset between δO2∕N2 and δ18Oatm records over the last 800 ka that we interpret as variations in the lagged response of δ18Oatm to precession. The largest offsets are identified during Terminations II, MIS 8 and MIS 16, corresponding to periods of destabilization of the Northern polar ice sheets. We therefore suggest that the occurrence of Heinrich–like events influences the response of δ18Oatm to precession.

Download Full-text

Representativeness of decadal-scale climate signals in ice-core aerosol records

10.5194/egusphere-egu2020-14381 ◽

2020 ◽

Author(s):

Tobias Erhardt ◽

Camilla Jensen ◽

Maria Hörhold ◽

Hubertus Fischer

Keyword(s):

High Resolution ◽

Time Scales ◽

Decadal Variability ◽

Ice Core ◽

Ice Cores ◽

Aerosol Deposition ◽

High Temporal Resolution ◽

Annual Layer ◽

Decadal Scale ◽

Climate Signals

<p>Records of past aerosol deposition to the polar ice sheets have enabled us to study variability in different parts of the earth system in great temporal detail over past glacial cycles. Furthermore, the high temporal resolution of ice-core aerosol records has been the basis for precise dating of climate records using annual layer counting. Nonetheless, the intermittent character of show deposition and especially the redistribution of snow on the surface of the ice sheet intrinsically affects the preservation of climate signals in the ice. This strongly limits how representative a climate record from a single ice core can be. It has been well established that even though seasonal variability might be preserved in an ice-core aerosol record, the inter annual variability of that record is different from a different core from the same site.</p><p>Until now most of the investigations have focused on inter annual representatives. This is mostly due to limited sample availability as multiple long records are needed for investigations on longer time scales. However, with the prospect of new high-resolution records over the Holocene from the EastGRIP ice core, understanding the representativeness of this record on decadal time scales is an important question. To tackle this problem, we use high-resolution aerosol records from multiple closely spaced ice cores from the EastGRIP deep ice core drill site. The records approximately cover the last millennium and are sub-seasonally resolved enabling the study of interannual to decadal variability over multiple aerosol species. All records are dated using annual layer counting and cross dating to the EastGRIP deep ice core using volcanic match points. In the presented pilot study, we focus on records of sea-salt and dust related aerosol species as well as on episodic aerosol signals from volcanos and wildfires.</p>

Download Full-text

A 485 year record of atmospheric chloride, nitrate and sulfate: results of chemical analysis of ice cores from Dyer Plateau, Antarctic Peninsula

Annals of Glaciology ◽

10.3189/s0260305500015792 ◽

1995 ◽

Vol 21 ◽

pp. 182-188 ◽

Cited By ~ 5

Author(s):

Jihong Cole Dai ◽

Lonnie G. Thompson ◽

Ellen Mosley-Thompson

Keyword(s):

Sea Water ◽

Accumulation Rate ◽

Linear Regression Analysis ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Sea Salt ◽

Volcanic Emissions ◽

Data Set ◽

Snow Chemistry

Detailed ionic analyses of Dyer Plateau snow show that major soluble impurities in snow consist of sodium (Na+), chloride (Cl−), nitrate (NO3−), sulfate (SO42−), and acidity (H+). The ratios of Na+ to Cl− concentrations are close to that of sea water, indicating little or no fractionation of sea-salt aerosols. The analyses of core sections from three sites along a 10 km transect show that local spatial variation of snow chemistry in this area is minimal and that temporal (decadal, inter-annual and sub-annual) variations in snow chemistry are very well preserved.Anion analyses of the upper 181 m section of two 235 m ice cores yield a data set of 485 years (1505-1989) of annual snow accumulation and fluxes of Cl−, NO3−, and non-sea-salt (nss) SO42−. No significant long-term trends are observed in any of the anion fluxes. This is consistent with other Antarctic ice-core records showing no significant anthropogenic atmospheric pollution in the high southern latitudes. Linear regression analysis shows that Cl− flux is independent of snow-accumulation rate. Significant positive correlations are found between accumulation rate and both NO3− flux and background nss-SO42− flux. These results suggest that dry deposition is primarily responsible for air-to-ground Cl− flux while wet deposition dominates the NO3− and nss-SO42− flux (≥90% and ≥75%, respectively). The nss-S042− fluxes provide a chronology of explosive volcanic emissions reaching the Antarctic region for the past 485 years.

Download Full-text