Forty years later: High resolution continuous flow analysis of the Dye3 ice core

<div>The Dye-3 ice core was drilled to bedrock at the Southern part of the central Greenland ice sheet (65&#176;11'N, 43&#176;50'W) in 1979-1981. The southern location is characterized by high accumulation rates compared to more central locations of the ice sheet. Since its drilling, numerous analyses of the core have been performed, and the ice has since been in freezer storage both in the USA and in Denmark.</div><div>In October and November 2019, the remaining ice, two mostly complete sections covering the depths of 1753&#8211;1820m and 1865&#8211;1918m of the Dye-3 core, were melted during a continuous flow analysis (CFA) campaign at the Physics of Ice, Climate, and Earth (PICE) group at the University of Copenhagen. The data represents both Holocene, Younger Dryas and Glacial sections (GS 5 to 12).</div><div>&#160;</div><div>The measured data consist chemistry and impurities contained in the ice, isotopes, as well as analysis of methane and other atmospheric gases.&#160;</div><div>The chemistry measurements include NH4+, Ca2+, and Na+&#160;ions, which besides being influenced by transport, provide information about forest fires, wind-blown dust, and sea ice, respectively, as well as acidity, which aids in the identification of volcanic events contained in the core. The quantity and grain size distribution of insoluble particles was analyzed by means of an Abakus laser particle counter.</div><div>&#160;</div><div>We compare the new high-resolution CFA record of dye3 with previous analysis and thus evaluate the progress made over 40 years. Further we compare overlapping time periods with other central Greenland ice cores and discuss spatial patterns in relation to the presented climate proxies.</div>

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High resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores

10.5194/essd-2021-324 ◽

2021 ◽

Author(s):

Tobias Erhardt ◽

Matthias Bigler ◽

Urs Federer ◽

Gideo Gfeller ◽

Daiana Leuenberger ◽

...

Keyword(s):

High Resolution ◽

Continuous Flow ◽

Ice Core ◽

Historical Context ◽

Flow Analysis ◽

Ice Cores ◽

Deposition Flux ◽

Concentration Data ◽

Continuous Flow Analysis ◽

North Greenland

Abstract. Records of chemical impurities from ice cores enable us to reconstruct the past deposition of aerosols onto the polar ice sheets and alpine glaciers. Through that, they allow us to gain insight into changes of the source, transport and deposition processes that ultimately determine the deposition flux at the coreing location. However, the low concentrations of the aerosol species in the ice and the resulting high risk of contamination poses a formidable analytical challenge, especially if long, continuous and highly resolved records are needed. Continuous Flow Analysis, CFA, the continuous melting, decontamination and analysis of ice-core samples has mostly overcome this issue and has quickly become the de-facto standard to obtain high-resolution aerosol records from ice cores after its inception at the University of Bern in the mid 90s. Here we present continuous records of calcium (Ca2+), sodium (Na+), ammonium (NH4+), nitrate (NO3−1) and electrolytic conductivity at 1 mm depth resolution from the NGRIP (North Greenland Ice Core Project) and NEEM (North Greenland Eemian Ice Drilling) ice cores produced by the Bern Continuous Flow Analysis group in the years 2000 to 2011. Both of the records have previously been used in a number of studies but have never been published in the full 1 mm resolution. Alongside the 1 mm datasets we provide decadal averages, a detailed description of the methods, relevant references, an assessment of the quality of the data and its usable resolution. Along the way we will also give some historical context on the development of the Bern CFA system.

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Calculating uncertainty for the RICE ice core continuous flow analysis water isotope record

Atmospheric Measurement Techniques ◽

10.5194/amt-11-4725-2018 ◽

2018 ◽

Vol 11 (8) ◽

pp. 4725-4736 ◽

Cited By ~ 2

Author(s):

Elizabeth D. Keller ◽

W. Troy Baisden ◽

Nancy A. N. Bertler ◽

B. Daniel Emanuelsson ◽

Silvia Canessa ◽

...

Keyword(s):

High Resolution ◽

Continuous Flow ◽

Ice Core ◽

Flow Analysis ◽

Calibration Error ◽

Data Set ◽

Total Uncertainty ◽

Continuous Flow Analysis ◽

Uncertainty Estimates ◽

Water Isotope

Abstract. We describe a systematic approach to the calibration and uncertainty estimation of a high-resolution continuous flow analysis (CFA) water isotope (δ2H, δ18O) record from the Roosevelt Island Climate Evolution (RICE) Antarctic ice core. Our method establishes robust uncertainty estimates for CFA δ2H and δ18O measurements, comparable to those reported for discrete sample δ2H and δ18O analysis. Data were calibrated using a time-weighted two-point linear calibration with two standards measured both before and after continuously melting 3 or 4 m of ice core. The error at each data point was calculated as the quadrature sum of three factors: Allan variance error, scatter over our averaging interval (error of the variance) and calibration error (error of the mean). Final mean total uncertainty for the entire record is δ2H=0.74 ‰ and δ18O=0.21 ‰. Uncertainties vary through the data set and were exacerbated by a range of factors, which typically could not be isolated due to the requirements of the multi-instrument CFA campaign. These factors likely occurred in combination and included ice quality, ice breaks, upstream equipment failure, contamination with drill fluid and leaks or valve degradation. We demonstrate that our methodology for documenting uncertainty was effective across periods of uneven system performance and delivered a significant achievement in the precision of high-resolution CFA water isotope measurements.

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Improved methodologies for continuous-flow analysis of stable water isotopes in ice cores

Atmospheric Measurement Techniques ◽

10.5194/amt-10-617-2017 ◽

2017 ◽

Vol 10 (2) ◽

pp. 617-632 ◽

Cited By ~ 14

Author(s):

Tyler R. Jones ◽

James W. C. White ◽

Eric J. Steig ◽

Bruce H. Vaughn ◽

Valerie Morris ◽

...

Keyword(s):

Continuous Flow ◽

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Isotope Ratio Mass Spectrometry ◽

Absorption Spectrometry ◽

Isotopic Analysis ◽

Water Isotopes ◽

Stable Water Isotopes ◽

Continuous Flow Analysis

Abstract. Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometry (LAS) performs as well or better than IRMS. The new LAS technology has been combined with continuous-flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system precision and mixing length into liquid and vapor components – useful measures for defining and improving the overall performance of the system. Critically, these methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the West Antarctic Ice Sheet (WAIS) Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ∼  1 m  ×  1.3 cm2 ice sticks to a temperature-controlled melt head, where the ice is converted to a continuous liquid stream and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the Vienna Standard Mean Ocean Water (VSMOW) scale, and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2  mm. As an added check on the system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS-CFA systems, including optimizing liquid and vapor mixing lengths, determining melt rates for ice cores with different accumulation and thinning histories, and removing system-wide mixing effects that are convolved with the natural diffusional signal that results primarily from water molecule diffusion in the firn column.

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First continuous high-resolution aerosol record from the East Greenland Ice Core Project (EGRIP), covering the last 15,000 years

10.5194/egusphere-egu2020-15202 ◽

2020 ◽

Author(s):

Camilla Marie Jensen ◽

Tobias Erhardt ◽

Giulia Sinnl ◽

Hubertus Fischer

Keyword(s):

High Resolution ◽

Biomass Burning ◽

Forest Fires ◽

Ice Core ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Background Level ◽

Volcanic Eruptions ◽

Atmospheric Conditions ◽

Data Set

Ice sheets are reliable archives of atmospheric impurities such as aerosols and gasses of both natural and anthropogenic origin. Impurity records from Greenland ice cores reveal much information about previous atmospheric conditions and long-range transport in the Northern hemisphere going back more than a hundred thousand years.Here we present the data from the upper 1,411 m from the EGRIP ice core, measuring conductivity, dust, sodium, calcium, ammonium, and nitrate. These records contain information about ocean sources, transport of terrestrial dust, soil and vegetation emissions as well as biomass burning, volcanic eruptions, etc., covering approximately the past 15,000 years. This newly obtained data set is unique as it provides the first high-resolution information about several thousands of years of the mid-Holocene period in Greenland that none of the previous impurity records from the other deep Greenland ice cores had managed to cover before due to brittle ice. This will contribute to further understanding of the atmospheric conditions for the pre-industrial period.The ammonium record contains peaks significantly higher than the background level. These peaks are caused by biomass burning or forest fires emitting plumes of ammonia large enough so that they can extend to the free troposphere and be efficiently transported all the way to the Greenland ice sheet. Here we present preliminary results of the wild fire frequency covering the entire Holocene, where the wild fires are defined as outliers in the ammonium record of annual means.

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Improved Methodologies for Continuous Flow Analysis of Stable Water Isotopes in Ice Cores

10.5194/amt-2016-118 ◽

2016 ◽

Cited By ~ 2

Author(s):

Tyler R. Jones ◽

James W. C. White ◽

Eric J. Steig ◽

Bruce H. Vaughn ◽

Valerie Morris ◽

...

Keyword(s):

Continuous Flow ◽

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Isotope Ratio Mass Spectrometry ◽

Isotopic Analysis ◽

Water Isotopes ◽

Mixing Length ◽

Stable Water Isotopes ◽

Continuous Flow Analysis

Abstract. Water isotopes in ice cores are used as a climate proxy for local temperature and regional atmospheric circulation as well as evaporative conditions in moisture source regions. Traditional measurements of water isotopes have been achieved using magnetic sector isotope ratio mass spectrometry (IRMS). However, a number of recent studies have shown that laser absorption spectrometers (LAS) perform as well or better than IRMS. The new LAS technology has been combined with continuous flow analysis (CFA) to improve data density and sample throughput in numerous prior ice coring projects. Here, we present a comparable semi-automated LAS-CFA system for measuring high-resolution water isotopes of ice cores. We outline new methods for partitioning both system uncertainty and system mixing length into liquid and vapor components – useful measures for defining and improving the overall performance of the system. Critically, our methods take into account the uncertainty of depth registration that is not present in IRMS nor fully accounted for in other CFA studies. We also explain a method for introducing consecutive sections of isotopically distinct ice at the melt head to define the system-wide mixing length. These analyses are achieved using samples from a South Pole firn core, a Greenland ice core, and the WAIS Divide ice core. The measurement system utilizes a 16-position carousel contained in a freezer to consecutively deliver ~ 1 m × 1.3 cm2 ice sticks to a temperature controlled melt head, where the ice is converted to a continuous liquid stream, and eventually vaporized using a concentric nebulizer for isotopic analysis. An integrated delivery system for water isotope standards is used for calibration to the VSMOW-SLAP scale and depth registration is achieved using a precise overhead laser distance device with an uncertainty of ±0.2 mm. As an added check on our system, we perform inter-lab LAS comparisons using WAIS Divide ice samples, a corroboratory step not taken in prior CFA studies. The overall results are important for substantiating data obtained from LAS-CFA systems, including optimizing liquid and vapor mixing lengths, determining melt rates for ice cores with different accumulation and thinning histories, and removing system-wide mixing effects that are convolved with the natural diffusional signal that results primarily from water molecule diffusion in the firn column.

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New δ18Oatm, δ18Oice and δDice profiles from deep ice of the TALDICE core

10.5194/egusphere-egu2020-4179 ◽

2020 ◽

Author(s):

Ilaria Crotti ◽

Carlo Barbante ◽

Massimo Frezzotti ◽

Wei Jiang ◽

Amaelle Landais ◽

...

Keyword(s):

High Resolution ◽

Ice Core ◽

Ice Sheet ◽

Ice Cores ◽

Radiometric Dating ◽

The Core ◽

Climatic Signal ◽

High Frequency Variability ◽

The One ◽

Depth Relationship

The study of the deep portions of ice cores still represents a poorly explored field due to the presence of processes acting in the lowermost layers and possibly affecting the preservation of the original climatic signal. For the 1620 m TALDICE ice core, drilled at Talos Dome (East Antarctica), the high-resolution climate reconstruction and chronology definition are available only until the depth of ~1450 m (150 kyr BP) (Stenni et al., 2011, Bazin et al., 2013). Our aim is to investigate the portion below 1460 m depth to the bottom of the core, where radargrams show the presence of an unconformity in the ice sheet, to define a preliminary chronology and identify a discernible climatic signal.Here we present the new TALDICE &#948;18Oatm record in the air bubbles, in association with the new high-resolution &#948;18Oice and &#948;Dice profiles and an 81Kr radiometric date. New 46 measurements of &#948;18Oatm&#160; allowed to increase the resolution of the available profile from 1357 to 1553.95 m depth and to extend the record till the bottom of the core at 1617 m depth. The comparison between the &#948;18Oatm profile of TALDICE and the one of EPICA Dome C (EDC) ice core (Extier et al., 2018) allows to solidly define a preliminary age-depth relationship for the TALDICE core until 1500 m depth, where the gas age is estimated to be ~200 kyr BP. Below 1500 m, supplementary &#948;18Oatm measurements will be needed to identify older precession cycles and to extend the age-depth relationship further back in time. On the other hand, the high-resolution isotopic profiles in the ice (18O/16O and D/H ratios) obtained below the depth of 1528 m and compared with the EDC ones suggest that the climatic signal in the ice is preserved until to the lower level of 1547.8 m, which is dated back to 343 kyr BP. However, the lack of similarities with the EDC water isotopes record below this depth, in spite of the 81 Kr radiometric age 459 &#177; 50 kyr BP at the depth of 1574-1578 m, indicates the missing of the MIS 11 in the isotopic profiles. Moreover, the increase of high-frequency variability in the &#948;18Oice and &#948;Dice below 1547.8 m depth implies that this part of the core lays in an area of the ice sheet characterized by different properties in comparison to the ice above.Additional &#948;18Oatm, 40Ar, &#948;18Oice, and &#948;Dice measurements will be performed in the lowermost portion of the core and the results will be compared with the new 81Kr radiometric dating at the depth of 1560-1564 m and 1614-1619 m to better constrain the chronology and to investigate the ice properties in the deeper portion of the core.

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Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

Environmental Science & Technology ◽

10.1021/es200118j ◽

2011 ◽

Vol 45 (10) ◽

pp. 4483-4489 ◽

Cited By ~ 56

Author(s):

Matthias Bigler ◽

Anders Svensson ◽

Ernesto Kettner ◽

Paul Vallelonga ◽

Maibritt E. Nielsen ◽

...

Keyword(s):

High Resolution ◽

Continuous Flow ◽

Flow Analysis ◽

Ice Cores ◽

Continuous Flow Analysis ◽

Climate Signals

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A High-Resolution Continuous Flow Analysis System for Polar Ice Cores

Bulletin of Glaciological Research ◽

10.5331/bgr.16r03 ◽

2016 ◽

Vol 34 (0) ◽

pp. 11-20 ◽

Cited By ~ 1

Author(s):

Rémi DALLMAYR ◽

Kumiko GOTO-AZUMA ◽

Helle ASTRID KJÆR ◽

Nobuhiko AZUMA ◽

Morimasa TAKATA ◽

...

Keyword(s):

High Resolution ◽

Continuous Flow ◽

Flow Analysis ◽

Ice Cores ◽

Polar Ice ◽

Continuous Flow Analysis ◽

Analysis System

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High-resolution continuous flow analysis setup for water isotopic measurement from ice cores using laser spectroscopy

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-12081-2014 ◽

2014 ◽

Vol 7 (12) ◽

pp. 12081-12124 ◽

Cited By ~ 1

Author(s):

B. D. Emanuelsson ◽

W. T. Baisden ◽

N. A. N. Bertler ◽

E. D. Keller ◽

V. Gkinis

Keyword(s):

Response Time ◽

Laser Spectroscopy ◽

Temporal Resolution ◽

Continuous Flow ◽

Ice Core ◽

Flow Analysis ◽

Ice Cores ◽

Flow Measurements ◽

Continuous Flow Analysis ◽

Δ18o And Δd

Abstract. Here we present an experimental setup for water stable isotopes (δ18O and δD) continuous flow measurements. It is the first continuous flow laser spectroscopy system that is using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS; analyzer manufactured by Los Gatos Research – LGR) in combination with an evaporation unit to continuously analyze sample from an ice core. A Water Vapor Isotopic Standard Source (WVISS) calibration unit, manufactured by LGR, was modified to: (1) increase the temporal resolution by reducing the response time (2) enable measurements on several water standards, and (3) to reduce the influence from memory effects. While this setup was designed for the Continuous Flow Analysis (CFA) of ice cores, it can also continuously analyze other liquid or vapor sources. The modified setup provides a shorter response time (~54 and 18 s for 2013 and 2014 setup, respectively) compared to the original WVISS unit (~62 s), which is an improvement in measurement resolution. Another improvement compared to the original WVISS is that the modified setup has a reduced memory effect. Stability tests comparing the modified WVISS and WVISS setups were performed and Allan deviations (σAllan) were calculated to determine precision at different averaging times. For the 2013 modified setup the precision after integration times of 103 s are 0.060 and 0.070‰ for δ18O and δD, respectively. For the WVISS setup the corresponding σAllan values are 0.030, 0.060 and 0.043‰ for δ18O, δD and δ17O, respectively. For the WVISS setup the precision is 0.035, 0.070 and 0.042‰ after 103 s for δ18O, δD and δ17O, respectively. Both the modified setups and WVISS setup are influenced by instrumental drift with δ18O being more drift sensitive than δD. The σAllan values for δ18O of 0.30 and 0.18‰ for the modified (2013) and WVISS setup, respectively after averaging times of 104 s (2.78 h). The Isotopic Water Analyzer (IWA)-modified WVISS setup used during the 2013 Roosevelt Island Climate Evolution (RICE) ice core processing campaign achieved high precision measurements, in particular for δD, with high temporal resolution for the upper part of the core, where a seasonally resolved isotopic signal is preserved.

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