ORCID Profile
0000-0001-9610-7141
Current Organisations
University of California, Irvine
,
University of Cambridge
,
Springer Nature New York
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Publications
Ice core chemistry database: an Antarctic compilation of sodium and sulfate records spanning the past 2000 years
Publisher: Copernicus GmbH
Date: 20-06-2023
DOI: 10.5194/ESSD-15-2517-2023
Abstract: Abstract. Changes in sea ice conditions and atmospheric circulation over the Southern Ocean play an important role in modulating Antarctic climate. However, observations of both sea ice and wind conditions are limited in Antarctica and the Southern Ocean, both temporally and spatially, prior to the satellite era (1970 onwards). Ice core chemistry data can be used to reconstruct changes over annual, decadal, and millennial timescales. To facilitate sea ice and wind reconstructions, the CLIVASH2k (CLimate Variability in Antarctica and the Southern Hemisphere over the past 2000 years) working group has compiled a database of two species, sodium [Na+] and sulfate [SO42-], commonly measured ionic species. The database (0.5285/9E0ED16E-F2AB-4372-8DF3-FDE7E388C9A7 Thomas et al., 2022) comprises records from 105 Antarctic ice cores, containing records with a maximum age duration of 2000 years. An initial filter has been applied, based on evaluation against sea ice concentration, geopotential height (500 hPa), and surface wind fields to identify sites suitable for reconstructing past sea ice conditions, wind strength, or atmospheric circulation.
Ice core chemistry database: an Antarctic compilation of sodium and sulphate records spanning the past 2000 years
Publisher: Copernicus GmbH
Date: 12-12-2022
Abstract: Abstract. Changes in sea ice conditions and atmospheric circulation over the Southern Ocean play an important role in modulating Antarctic climate. However, observations of both sea ice and wind conditions are limited in Antarctica and the Southern Ocean, both temporally and spatially. Ice core chemistry data can be used to reconstruct changes over annual, decadal, and millennial timescales. To facilitate sea ice and wind reconstructions, the CLIVASH2k working group has compiled a database of two species, sodium [Na+] and sulphate [SO42-], commonly measured ionic species. The database contains records from 105 Antarctic ice cores, containing records with a maximum age duration of 2000 years. An initial filter has been applied, based on evaluation against climate observations, to identify sites suitable for reconstructing past sea ice conditions, wind strength, or atmospheric circulation.
Supplementary material to Ice core chemistry database: an Antarctic compilation of sodium and sulphate records spanning the past 2000 years
Publisher: Copernicus GmbH
Date: 12-12-2022
Supplementary material to The ST22 chronology for the Skytrain Ice Rise ice core – part 1: A stratigraphic chronology of the last 2000 years
Publisher: Copernicus GmbH
Date: 23-03-2022
The ST22 chronology for the Skytrain Ice Rise ice core – Part 1: A stratigraphic chronology of the last 2000 years
Publisher: Copernicus GmbH
Date: 10-08-2022
Abstract: Abstract. A new ice core was drilled in West Antarctica on Skytrain Ice Rise in field season 2018/2019. This 651 m ice core is one of the main targets of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project. A present-day accumulation rate of 13.5 cm w.e. yr−1 was derived. Although the project mainly aims to investigate the last interglacial (115–130 ka), a robust chronology period covering the recent past is needed to constrain the age models for the deepest ice. Additionally, this time period is important for understanding current climatic changes in the West Antarctic region. Here, we present a stratigraphic chronology for the top 184.14 m of the Skytrain ice core based on absolute age tie points interpolated using annual layer counting encompassing the last 2000 years of climate history. Together with a model-based depth–age relationship of the deeper part of the ice core, this will form the ST22 chronology. The chemical composition, dust content, liquid conductivity, water isotope concentration and methane content of the whole core was analysed via continuous flow analysis (CFA) at the British Antarctic Survey. Annual layer counting was performed by manual counting of seasonal variations in mainly the sodium and calcium records. This counted chronology was informed and anchored by absolute age tie points, namely, the tritium peak (1965 CE) and six volcanic eruptions. Methane concentration variations were used to further constrain the counting error. A minimal error of ±1 year at the tie points was derived, accumulating to ± 5 %–10 % of the age in the unconstrained sections between tie points. This level of accuracy enables data interpretation on at least decadal timescales and provides a solid base for the dating of deeper ice, which is the second part of the chronology.
A high-accuracy Total Air Content setup: System performance and first results from Skytrain Ice Rise, Antarctica
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-9210
Abstract: & & Some modelling studies and sea level reconstructions suggest the loss of the West Antarctic Ice Sheet (WAIS) during the Last Interglacial (LIG) about ~120& #8217 ago, but direct evidence for a collapse of the WAIS is lacking. The WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial (WACSWAIN) project aims at providing direct evidence allowing for a comprehensive assessment of whether or not the WAIS collapsed during the LIG. One of the expected consequences of such massive ice mass loss is the change of the elevation of land masses in close proximity of the WAIS due to isostatic adjustments. This process, together with changes in ice sheet thickness, may have altered the elevation of Skytrain Ice Rise above sea level on the order of 200 m. Such major changes in the elevation should be imprinted in the Total Air Content (TAC) based on simple barometric considerations. Here we present a new experimental setup of a high-accuracy, high-precision TAC measurement system constructed at the British Antarctic Survey. This setup is dedicated to and optimised for the measurement of TAC and is based on a vacuum extraction principle. The air is extracted from the ice by melting the s le by thermal radiation and the released air is dried and directly expanded into a 30-litre expansion chamber. State-of-the-art pressure gauges and thorough temperature control allow for an accuracy of 0.2% with a real ice reproducibility of 0.2% to 0.4% for 100 g and 30 g s les, respectively. Here, we discuss the performance of this new TAC system and present first TAC data from the Holocene section of the Skytrain Ice Core, Antarctica.& &
The ST22 chronology for the Skytrain Ice Rise ice core – part 1: A stratigraphic chronology of the last 2000 years
Publisher: Copernicus GmbH
Date: 23-03-2022
DOI: 10.5194/CP-2022-28
Abstract: Abstract. A new ice core was drilled in West Antarctica on Skytrain Ice Rise in field season 2018 / 2019. This 651 m ice core is one of the main targets of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project. A present-day accumulation rate of 13.5 cm w.e./year was derived. Although the project mainly aims to investigate the last interglacial (115–130 ka BP), a robust chronology period covering the recent past is needed to constrain the age models for the deepest ice. Additionally, this time period is important for understanding current climatic changes in theWest Antarctic region. Here, we present a stratigraphic chronology for the top 184.14 m of the Skytrain ice core covering the last 2000 years based on absolute age tie points interpolated using annual layer counting encompassing the last 2000 years of climate history. Together with a model-based depth-age relationship of the deeper part of the ice core, this will form the ST22 chronology. The chemical composition, dust content, liquid conductivity, water isotope concentration and methane content of the whole core was analysed via continuous flow analysis (CFA) at the British Antarctic Survey. Annual layer counting was performed by manual counting of seasonal variations in mainly the sodium and calcium records. This counted chronology was informed and anchored by absolute age tie points, namely, the tritium peak (1965 CE) and six volcanic eruptions. Methane concentration variations were used to further constrain the counting error. A minimal error of ± 1 year at the tie points was derived, accumulating to ± 5–10 % of the age in the unconstrained sections between tie points. This level of accuracy enables data interpretation on at least decadal timescales and provides a solid base for the dating of deeper ice, which is the second part of the chronology.
Related Organisations
University Of Cambridge
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for Mackenzie Grieman.