44 results on '"Schüpbach, Simon"'
Search Results
2. High-resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores
- Author
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Erhardt, Tobias, Bigler, Matthias, Federer, Urs, Gfeller, Gideon, Leuenberger, Daiana, Stowasser, Olivia, Röthlisberger, Regine, Schüpbach, Simon, Ruth, Urs, Twarloh, Birthe, Wegner, Anna, Goto-Azuma, Kumiko, Kuramoto, Takayuki, Kjaer, Helle A., Vallelonga, Paul T., Siggaard-Andersen, Marie-Louise, Hansson, Margareta E., Benton, Ailsa K., Fleet, Louise G., Mulvaney, Rob, Thomas, Elizabeth R., Abram, Nerilie, Stocker, Thomas F., Fischer, Hubertus, Erhardt, Tobias, Bigler, Matthias, Federer, Urs, Gfeller, Gideon, Leuenberger, Daiana, Stowasser, Olivia, Röthlisberger, Regine, Schüpbach, Simon, Ruth, Urs, Twarloh, Birthe, Wegner, Anna, Goto-Azuma, Kumiko, Kuramoto, Takayuki, Kjaer, Helle A., Vallelonga, Paul T., Siggaard-Andersen, Marie-Louise, Hansson, Margareta E., Benton, Ailsa K., Fleet, Louise G., Mulvaney, Rob, Thomas, Elizabeth R., Abram, Nerilie, Stocker, Thomas F., and Fischer, Hubertus
- Abstract
Records of chemical impurities from ice cores enable us to reconstruct the past deposition of aerosols onto polar ice sheets and alpine glaciers. Through this they allow us to gain insight into changes of the source, transport and deposition processes that ultimately determine the deposition flux at the coring location. However, the low concentrations of the aerosol species in the ice and the resulting high risk of contamination pose 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-1990s. Here, we present continuous records of calcium (Ca2+), sodium (Na+), ammonium (NH+4), nitrate (NO-3) 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 (Erhardt et al., 2021). Both of the records were previously used in a number of studies but were never published in 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.
- Published
- 2022
- Full Text
- View/download PDF
3. Mode change of millennial CO₂ variability during the last glacial cycle associated with a bipolar marine carbon seesaw
- Author
-
Bereiter, Bernhard, Lüthi, Dieter, Siegrist, Michael, Schüpbach, Simon, Stocker, Thomas F., and Fischer, Hubertus
- Published
- 2012
4. High-resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores
- Author
-
Erhardt, Tobias, primary, Bigler, Matthias, additional, Federer, Urs, additional, Gfeller, Gideon, additional, Leuenberger, Daiana, additional, Stowasser, Olivia, additional, Röthlisberger, Regine, additional, Schüpbach, Simon, additional, Ruth, Urs, additional, Twarloh, Birthe, additional, Wegner, Anna, additional, Goto-Azuma, Kumiko, additional, Kuramoto, Takayuki, additional, Kjær, Helle A., additional, Vallelonga, Paul T., additional, Siggaard-Andersen, Marie-Louise, additional, Hansson, Margareta E., additional, Benton, Ailsa K., additional, Fleet, Louise G., additional, Mulvaney, Rob, additional, Thomas, Elizabeth R., additional, Abram, Nerilie, additional, Stocker, Thomas F., additional, and Fischer, Hubertus, additional
- Published
- 2022
- Full Text
- View/download PDF
5. High resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores
- Author
-
Erhardt, Tobias, primary, Bigler, Matthias, additional, Federer, Urs, additional, Gfeller, Gideo, additional, Leuenberger, Daiana, additional, Stowasser, Olivia, additional, Röthlisberger, Regine, additional, Schüpbach, Simon, additional, Ruth, Urs, additional, Twarloh, Birthe, additional, Wegner, Anna, additional, Goto-Azuma, Kumiko, additional, Kuramoto, Takayuki, additional, Kjær, Helle A., additional, Vallelonga, Paul T., additional, Siggaard-Andersen, Marie-Louise, additional, Hansson, Margaretha E., additional, Benton, Ailsa K., additional, Fleet, Louise G., additional, Mulvaney, Rob, additional, Thomas, Elizabeth R., additional, Abram, Nerilie, additional, Stocker, Thomas F., additional, and Fischer, Hubertus, additional
- Published
- 2021
- Full Text
- View/download PDF
6. Iron in the NEEM ice core relative to Asian loess records over the last glacial–interglacial cycle
- Author
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Xiao, Cunde, primary, Du, Zhiheng, additional, Handley, Mike J, additional, Mayewski, Paul A, additional, Cao, Junji, additional, Schüpbach, Simon, additional, Zhang, Tong, additional, Petit, Jean-Robert, additional, Li, Chuanjin, additional, Han, Yeongcheol, additional, Li, Yuefang, additional, and Ren, Jiawen, additional
- Published
- 2020
- Full Text
- View/download PDF
7. High resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores.
- Author
-
Erhardt, Tobias, Bigler, Matthias, Federer, Urs, Gfeller, Gideo, Leuenberger, Daiana, Stowasser, Olivia, Röthlisberger, Regine, Schüpbach, Simon, Ruth, Urs, Twarloh, Birthe, Wegner, Anna, Goto-Azuma, Kumiko, Kuramoto, Takayuki, Kjær, Helle A., Vallelonga, Paul T., Siggaard-Andersen, Marie-Louise, Hansson, Margaretha E., Benton, Ailsa K., Fleet, Louise G., and Mulvaney, Rob
- Subjects
ICE cores ,NEEM ,GREENLAND ice ,AEROSOLS ,ALPINE glaciers ,ICE sheets - 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 (Ca
2+ ), 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. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
8. Iron in the NEEM ice core relative to Asian loess records over the last glacial–interglacial cycle.
- Author
-
Xiao, Cunde, Du, Zhiheng, Handley, Mike J, Mayewski, Paul A, Cao, Junji, Schüpbach, Simon, Zhang, Tong, Petit, Jean-Robert, Li, Chuanjin, Han, Yeongcheol, Li, Yuefang, and Ren, Jiawen
- Subjects
ICE cores ,NEEM ,MINERAL dusts ,LAST Glacial Maximum ,LOESS ,BIOMASS burning - Abstract
Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO
2 ) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial–interglacial cycle in response to Earth's orbital cycles. In the last glacial–interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
9. Decadal-scale progression of the onset of Dansgaard–Oeschger warming events
- Author
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Erhardt, Tobias, primary, Capron, Emilie, additional, Rasmussen, Sune Olander, additional, Schüpbach, Simon, additional, Bigler, Matthias, additional, Adolphi, Florian, additional, and Fischer, Hubertus, additional
- Published
- 2019
- Full Text
- View/download PDF
10. Decadal-scale progression of Dansgaard-Oeschger warming events
- Author
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Erhardt, Tobias, primary, Capron, Emilie, additional, Rasmussen, Sune Olander, additional, Schüpbach, Simon, additional, Bigler, Matthias, additional, Adolphi, Florian, additional, and Fischer, Hubertus, additional
- Published
- 2018
- Full Text
- View/download PDF
11. Supplementary material to "Decadal-scale progression of Dansgaard-Oeschger warming events"
- Author
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Erhardt, Tobias, primary, Capron, Emilie, additional, Rasmussen, Sune Olander, additional, Schüpbach, Simon, additional, Bigler, Matthias, additional, Adolphi, Florian, additional, and Fischer, Hubertus, additional
- Published
- 2018
- Full Text
- View/download PDF
12. Ice cores:High-resolution archive of rapid climate changes
- Author
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Schüpbach, Simon, Fischer, H., Rasmussen, Sune Olander, Svensson, Anders, Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, and White, J.W.C.
- Published
- 2016
13. Decadal-scale progression of Dansgaard-Oeschger warming events.
- Author
-
Erhardt, Tobias, Capron, Emilie, Rasmussen, Sune Olander, Schüpbach, Simon, Bigler, Matthias, Adolphi, Florian, and Fischer, Hubertus
- Abstract
During the last glacial period, proxy records throughout the Northern Hemisphere document a succession of rapid millennial-scale warming events, called Dansgaard-Oeschger (DO) events. A range of different mechanisms have been proposed that can produce similar warming in model experiments, however the progression and ultimate trigger of the events is still unknown. Because of their fast nature, the progression is challenging to reconstruct from paleoclimate data due to the limited temporal resolution achievable in many archives and cross-dating uncertainties between records. Here we use new high-resolution multi-proxy records of sea-salt (derived from sea spray and sea ice over the North Atlantic) and terrestrial (derived from the Central Asian deserts) aerosol concentrations over the period 10-60 ka from the Greenland NGRIP and NEEM ice cores in conjunction with local precipitation and temperature proxies from one of the cores to investigate the progression of environmental changes at the onset of the warming events at annual to multi-annual resolution. Our results show on average a small lead of the changes in both local precipitation and terrestrial dust aerosol concentrations over the change in sea-salt aerosol concentrations and local temperature of approximately one decade. This suggests that, connected to the reinvigoration of the Atlantic Meridional Overturning Circulation and the warming in the North Atlantic, both synoptic and hemispheric atmospheric circulation change at the onset of the DO warming, affecting both the moisture transport to Greenland and the Asian monsoon systems. Taken at face value, this suggests that a collapse of the sea-ice cover was not the initial trigger for the DO events. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
14. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores
- Author
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Dallmayr, Remi, Goto-Azuma, Kumiko, Kjær, Helle Astrid, Azuma, Nobuhiko, Takata, Morimasa, Schüpbach, Simon, Hirabayashi, Motohiro, Dallmayr, Remi, Goto-Azuma, Kumiko, Kjær, Helle Astrid, Azuma, Nobuhiko, Takata, Morimasa, Schüpbach, Simon, and Hirabayashi, Motohiro
- Abstract
In recent decades, the development of continuous flow analysis (CFA) technology for ice core analysis has enabled greater sample throughput and greater depth resolution compared with the classic discrete sampling technique. We developed the first Japanese CFA system at the National Institute of Polar Research (NIPR) in Tokyo. The system allows the continuous analysis of stable water isotopes and electrical conductivity, as well as the collection of discrete samples from both inner and outer parts of the core. This CFA system was designed to have sufficiently high temporal resolution to detect signals of abrupt climate change in deep polar ice cores. To test its performance, we used the system to analyze different climate intervals in ice drilled at the NEEM (North Greenland Eemian Ice Drilling) site, Greenland. The quality of our continuous measurement of stable water isotopes has been confirmed through a comparison with different datasets. Moreover, our system presents a better measurement efficiency to resolve the signal of electrical conductivity in the ice core sample than that obtained with a similar system developed by the University of Bern, Switzerland, during a field campaign at NEEM camp.
- Published
- 2016
15. Multiple sources of Greenland dust throughout the Holocene
- Author
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Kettner, Ernesto, Wegner, Anna, Erhardt, Tobias, Schüpbach, Simon, Svensson, Anders, and Fiore, Saverio
- Subjects
530 Physics - Abstract
It is contested that the mineral dust found in Greenlandic ice cores during the Holocene stems from multiple source areas. Particles entrained above a more productive, primary source dominate the signal’s multi-seasonal average. Data in sub-annual resolution, however, reveal at least one further source. Whereas distinct inputs from the primary source are visible in elevated concentration levels, various inputs of the secondary source(s) are reflected by multiple maxima in the coarse particle percentage. As long as the dust sources’ respective seasonal cycles are preserved, primary and secondary source can be distinguished. Since the two source’s ejecta eventually detected differ in size, which can be attributed to a change in atmospheric residence times, it is suggested that the secondary source is located in closer proximity to the drilling site than the primary one.
- Published
- 2014
16. Evaluation of aeolian dust records obtained from Polar Ice Cores
- Author
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Kettner, Ernesto, Grinsted, Aslak, Wegner, Anna, Petit, Jean Robert, Erhardt, Tobias, Schüpbach, Simon, Vallelonga, Paul, Svensson, Anders, and Fiore, Saverio
- Subjects
530 Physics - Abstract
When an ice core sample is analysed for its aeolian dust content, it is melted and the particles detected are suspended in water. Consequently, dust measurement techniques employed in the ice core community differ from those used for in-situ studies of airborne dust. Methods commonly used to classify insolubles suspended in a liquid are either based on the particles’ interaction with light or on the detection of resistive pulses by means of Coulter counting. Data sets obtained with Coulter counters are widely accepted as references and other techniques are judged against their ability to reproduce these. Unfortunately, optically acquired ice core dust records were found to differ. By analyzing two sections of the NEEM dust record, two different evaluation procedures are discussed before a third protocol is proposed. It is found that relative changes in the archived dust load can be reproduced, while the simultaneous attainment of absolute concentrations or changes in the grain size frequency histograms in high resolution remains difficult.
- Published
- 2014
17. Boreal fire records in Northern Hemisphere ice cores: a review
- Author
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Legrand, Michel, primary, McConnell, Joseph, additional, Fischer, Hubertus, additional, Wolff, Eric W., additional, Preunkert, Susanne, additional, Arienzo, Monica, additional, Chellman, Nathan, additional, Leuenberger, Daiana, additional, Maselli, Olivia, additional, Place, Philip, additional, Sigl, Michael, additional, Schüpbach, Simon, additional, and Flannigan, Mike, additional
- Published
- 2016
- Full Text
- View/download PDF
18. Ice cores: High-resolution archive of rapid climate changes
- Author
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Schüpbach, Simon, primary, Fischer, H, additional, Rasmussen, SO, additional, Svensson, A, additional, Dahl-Jensen, D, additional, Steffensen, JP, additional, and White, JWC, additional
- Published
- 2016
- Full Text
- View/download PDF
19. Geochemical and Microbiological Studies of Nitrous Oxide Variations within the New NEEM Greenland Ice Core during the Last Glacial Period
- Author
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Miteva, Vanya, primary, Sowers, Todd, additional, Schüpbach, Simon, additional, Fischer, Hubertus, additional, and Brenchley, Jean, additional
- Published
- 2016
- Full Text
- View/download PDF
20. A High-Resolution Continuous Flow Analysis System for Polar Ice Cores
- Author
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DALLMAYR, Rémi, primary, GOTO-AZUMA, Kumiko, additional, ASTRID KJÆR, Helle, additional, AZUMA, Nobuhiko, additional, TAKATA, Morimasa, additional, SCHÜPBACH, Simon, additional, and HIRABAYASHI, Motohiro, additional
- Published
- 2016
- Full Text
- View/download PDF
21. Lasterabtragung an einer Überbauung in Konstanz : Neubauprojektierung eines Hotel- und Bürogebäudes im Seerhein-Areal in Konstanz
- Author
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Heuvel, Dominik van den, Rohrbach, Robert, and Schüpbach, Simon
- Published
- 2011
- Full Text
- View/download PDF
22. Chemical compositions of solid particles present in the Greenland NEEM ice core over the last 110,000 years
- Author
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Oyabu, Ikumi, primary, Iizuka, Yoshinori, additional, Fischer, Hubertus, additional, Schüpbach, Simon, additional, Gfeller, Gideon, additional, Svensson, Anders, additional, Fukui, Manabu, additional, Steffensen, Jørgen Peder, additional, and Hansson, Margareta, additional
- Published
- 2015
- Full Text
- View/download PDF
23. Millennial changes in North American wildfire and soil activity over the last glacial cycle
- Author
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Fischer, Hubertus, primary, Schüpbach, Simon, additional, Gfeller, Gideon, additional, Bigler, Matthias, additional, Röthlisberger, Regine, additional, Erhardt, Tobias, additional, Stocker, Thomas F., additional, Mulvaney, Robert, additional, and Wolff, Eric W., additional
- Published
- 2015
- Full Text
- View/download PDF
24. Multiple sources of Greenland dust throughout the Holocene
- Author
-
Fiore, Saverio, Kettner, Ernesto, Wegner, Anna, Erhardt, Tobias, Schüpbach, Simon, Svensson, Anders, Fiore, Saverio, Kettner, Ernesto, Wegner, Anna, Erhardt, Tobias, Schüpbach, Simon, and Svensson, Anders
- Abstract
It is contested that the mineral dust found in Greenlandic ice cores during the Holocene stems from multiple source areas. Particles entrained above a more productive, primary source dominate the signal’s multi-seasonal average. Data in sub-annual resolution, however, reveal at least one further source. Whereas distinct inputs from the primary source are visible in elevated concentration levels, various inputs of the secondary source(s) are reflected by multiple maxima in the coarse particle percentage. As long as the dust sources’ respective seasonal cycles are preserved, primary and secondary source can be distinguished. Since the two source’s ejecta eventually detected differ in size, which can be attributed to a change in atmospheric residence times, it is suggested that the secondary source is located in closer proximity to the drilling site than the primary one.
- Published
- 2014
25. Evaluation of aeolian dust records obtained from Polar Ice Cores
- Author
-
Fiore, Saverio, Kettner, Ernesto, Grindsted, Aslak, Wegner, Anna, Petit, Jean Robert, Erhardt, Tobias, Schüpbach, Simon, Vallelonga, Paul, Svensson, Anders, Fiore, Saverio, Kettner, Ernesto, Grindsted, Aslak, Wegner, Anna, Petit, Jean Robert, Erhardt, Tobias, Schüpbach, Simon, Vallelonga, Paul, and Svensson, Anders
- Abstract
When an ice core sample is analysed for its aeolian dust content, it is melted and the particles detected are suspended in water. Consequently, dust measurement techniques employed in the ice core community differ from those used for in-situ studies of airborne dust. Methods commonly used to classify insolubles suspended in a liquid are either based on the particles’ interaction with light or on the detection of resistive pulses by means of Coulter counting. Data sets obtained with Coulter counters are widely accepted as references and other techniques are judged against their ability to reproduce these. Unfortunately, optically acquired ice core dust records were found to differ. By analyzing two sections of the NEEM dust record, two different evaluation procedures are discussed before a third protocol is proposed. It is found that relative changes in the archived dust load can be reproduced, while the simultaneous attainment of absolute concentrations or changes in the grain size frequency histograms in high resolution remains difficult.
- Published
- 2014
26. Atmospheric nitrous oxide during the last 140,000 years
- Author
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Schilt, Adrian, Baumgartner, Matthias, Schwander, Jakob, Buiron, Daphné, Capron, Emilie, Chappellaz, Jérôme, Loulergue, Laetitia, Schüpbach, Simon, Spahni, Renato, Fischer, Hubertus, and Stocker, Thomas F.
- Published
- 2010
- Full Text
- View/download PDF
27. A new method for high-resolution methane measurements on polar ice cores using continuous flow analysis
- Author
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Schüpbach, Simon, Federer, Urs, Kaufmann, Patrik R., Hutterli, Manuel A., Buiron, Daphné, Blunier, Thomas, Fischer, Hubertus, Stocker, Thomas F., Schüpbach, Simon, Federer, Urs, Kaufmann, Patrik R., Hutterli, Manuel A., Buiron, Daphné, Blunier, Thomas, Fischer, Hubertus, and Stocker, Thomas F.
- Abstract
Methane (CH4) is the second most important anthropogenic greenhouse gas in the atmosphere. Rapid variations of the CH4 concentration, as frequently registered, for example during the last ice age, have been used as reliable time markers for the definition of a common time scale of polar ice cores. In addition, these variations indicate changes in the sources of methane primarily associated with the presence of wetlands. In order to determine the exact time evolution of such fast concentration changes, CH4 measurements of the highest resoution in the ice core archive are required. Here,we present a new, semicontinuous and field-deployable CH4 detection method, which was incorporated in a continuous flow analysis (CFA) system. In CFA, samples cut along the axis of an ice core are melted at a melt speed of typically 3.5 cm/min. The air from bubbles in the ice core is extracted continuously from the meltwater and forwarded to a gas chromatograph (GC) for high-resolution CH4 Measurements, The GC performs a measurement every 3.5 min, hence, a depth resolution of 15 cm is achieved at the chosen melt rate. An even higher resolution is not necessary due to the low pass filtering of air in ice cores caused by the slow bubble enclosure process and the diffusion of air in firn. Reproducibility of the new method is 3%, thus, for a typical CH4 concentration of 500 ppb during an ice age, this corresponds to an absolute precision of 15 ppb, comparable to traditional analyses on discrete samples. Results of CFA-CH4 measurements on the ice core from Talos Dome (Antarctica) illustrate the much higher temporal resolution of our method compared with established melt-refreeze CH4 measurements and demonstrate the feasibility of the new method.
- Published
- 2009
28. An improved continuous flow analysis system for high-resolution field measurements on ice cores
- Author
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Kaufmann, Patrik R., Federer, Urs, Hutterli, Manuel A., Bigler, Matthias, Schüpbach, Simon, Ruth, Urs, Schmitt, Jochen, Stocker, Thomas F., Kaufmann, Patrik R., Federer, Urs, Hutterli, Manuel A., Bigler, Matthias, Schüpbach, Simon, Ruth, Urs, Schmitt, Jochen, and Stocker, Thomas F.
- Abstract
Continuous flow analysis (CFA) is a well-established method to obtain information about impurity contents in ice cores as indicators of past changes in the climate system. A section of an ice core is continuously melted on a melter head supplying a sample water flow which is analyzed online. This provides high depth and time resolution of the ice core records and very efficient sample decontamination as only the inner part of the ice sample is analyzed. Here we present an improved CFA system which has been totally redesigned in view of a significantly enhanced overall efficiency and flexibility, signal quality, compactness, and ease of use. These are critical requirements especially for operations of CFA during field campaigns, e.g., in Antarctica or Greenland. Furthermore,a novel device to measure the total air content in the ice was developed. Subsequently, the air bubbles are now extracted continuously from the sample water flow for subsequent gas measurements.
- Published
- 2008
29. Continuous flow analysis of total organic carbon in polar ice cores
- Author
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Federer, Urs, Kaufmann, Patrik R., Hutterli, Manuel A., Schüpbach, Simon, Stocker, Thomas F., Federer, Urs, Kaufmann, Patrik R., Hutterli, Manuel A., Schüpbach, Simon, and Stocker, Thomas F.
- Abstract
Ice cores are a widely used archive to reconstruct past changes of the climate system. This is done by measuring the concentration of substances in the ice and in the air of bubbles enclosed in ice. Some species pertaining to the carbon cycle (e.g., CO2, CH4) are routinely measured. However, information about the organic fraction of the impurities in polar ice is still very limited. Therefore, we developed a new method to determine the content of total organic carbon (TOC) in ice cores using a continuous flow analysis (CFA) system. The method is based on photochemical oxidation of TOC and the electrolytic quantification of theCO2 producedduring oxidation. The TOC instrument features a limit of detection of 2 ppbC and a response time of 60 s at a sample flow rate of 0.7 mL/ min and a linear measurement range of 2-4000 ppbC. First measurements on the ice core from Talos Dome, Antarctica, reveal TOC concentrations varying between 80 and 360 ppbC in the 20 m section presented.
- Published
- 2008
30. Mode change of millennial CO 2 variability during the last glacial cycle associated with a bipolar marine carbon seesaw
- Author
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Bereiter, Bernhard, primary, Lüthi, Dieter, additional, Siegrist, Michael, additional, Schüpbach, Simon, additional, Stocker, Thomas F., additional, and Fischer, Hubertus, additional
- Published
- 2012
- Full Text
- View/download PDF
31. Continuous Flow Analysis of Total Organic Carbon in Polar Ice Cores
- Author
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Federer, Urs, primary, Kaufmann, Patrik R., additional, Hutterli, Manuel A., additional, Schüpbach, Simon, additional, and Stocker, Thomas F., additional
- Published
- 2008
- Full Text
- View/download PDF
32. An Improved Continuous Flow Analysis System for High-Resolution Field Measurements on Ice Cores
- Author
-
Kaufmann, Patrik R., primary, Federer, Urs, additional, Hutterli, Manuel A., additional, Bigler, Matthias, additional, Schüpbach, Simon, additional, Ruth, Urs, additional, Schmitt, Jochen, additional, and Stocker, Thomas F., additional
- Published
- 2008
- Full Text
- View/download PDF
33. Fourier reconstruction in optoacoustic imaging using truncated regularized inverse k -space interpolation
- Author
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Jaeger, Michael, primary, Schüpbach, Simon, additional, Gertsch, Andreas, additional, Kitz, Michael, additional, and Frenz, Martin, additional
- Published
- 2007
- Full Text
- View/download PDF
34. Mode change of millennial C02 variability during the last glacial cycle associated with a bipolar marine carbon seesaw.
- Author
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Bereiter, Bernhard, Lüthi, Dieter, Siegrist, Michael, Schüpbach, Simon, Stockera, Thomas F., and Fischer, Hubertus
- Subjects
CLIMATE change ,GLOBAL warming ,PLEISTOCENE Epoch ,OCEAN circulation ,OCEAN temperature ,CARBON content of water ,ICE cores - Abstract
Important elements of natural climate variations during the last ice age are abrupt temperature increases over Greenland and related warming and cooling periods over Antarctica. Records from Antarctic ice cores have shown that the global carbon cycle also plays a role in these changes. The available data shows that atmospheric C0
2 follows closely temperatures reconstructed from Antarctic ice cores during these variations. Here, we present new high-resolution C02 data from Antarctic ice cores, which cover the period between 115,000 and 38,000 y before present. Our measurements show that also smaller Antarctic warming events have an imprint in C02 concentrations. Moreover, they indicate that during Marine Isotope Stage (MIS) 5, the peak of millennial C02 variations lags the onset of Dansgaard/Oeschger warmings by 250 ± 190 y. During MIS 3, this lag increases significantly to 870 ± 90 y. Considerations of the ocean circulation suggest that the millennial variability associated with the Atlantic Meridional Overturning Circulation (AMOC) undergoes a mode change from MIS 5 to MIS 4 and 3. Ocean carbon inventory estimates imply that during MIS 3 additional carbon is derived from an extended mass of carbon-enriched Antarctic Bottom Water. The absence of such a carbon-enriched water mass in the North Atlantic during MIS 5 can explain the smaller amount of carbon released to the atmosphere after the Antarctic temperature maximum and, hence, the shorter lag. Our new data provides further constraints for transient coupled carbon cycleclimate simulations during the entire last glacial cycle. [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
- View/download PDF
35. Method for the determination of specific molecular markers of biomass burning in lake sediments
- Author
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Kehrwald, N., Barbante, C., McWethy, D.B., Schüpbach, Simon, and Kirchgeorg, T.
- Subjects
13. Climate action ,530 Physics - Abstract
Fire has an influence on regional to global atmospheric chemistry and climate. Molecular markers of biomass burning archived in lake sediments are becoming increasingly important in paleoenvironmental reconstruction and may help determine the interaction between climate and fire activity. Here, we present a high performance anion exchange chromatography–mass spectrometry method to allow separation and analysis of levoglucosan, mannosan and galactosan in lake sediments, with implications for reconstructing past biomass burning events. Determining mannosan and galactosan in Lake Kirkpatrick, New Zealand (45.03°S, 168.57°E) sediment cores and comparing these isomers with the more abundant biomass burning markers levoglucosan and charcoal represents a significant advancement in our ability to analyze past fire activity. Levoglucosan, mannosan and galactosan concentrations correlated significantly with macroscopic charcoal concentration. Levoglucosan/mannosan and levoglucosan/(mannosan + galactosan) ratios may help determine not only when fires occurred, but also if changes in the primary burned vegetation occurred.
36. Chemical compositions of solid particles present in the Greenland NEEM ice core over the last 110,000 years
- Author
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Steffensen, Jørgen Peder, Fischer, Hubertus, Fukui, Manabu, Svensson, Anders, Oyabu, Ikumi, Hansson, Margareta, Iizuka, Yoshinori, Gfeller, Gideon, and Schüpbach, Simon
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13. Climate action ,530 Physics - Abstract
This study reports the chemical composition of particles present along Greenland’s North Greenland Eemian Ice Drilling (NEEM) ice core, back to 110,000 years before present. Insoluble and soluble particles larger than 0.45 μm were extracted from the ice core by ice sublimation, and their chemical composition was analyzed using scanning electron microscope and energy dispersive X-ray spectroscopy and micro-Raman spectroscopy. We show that the dominant insoluble components are silicates, whereas NaCl, Na₂SO₄, CaSO ₄, and CaCO₃ represent major soluble salts. For the first time, particles of CaMg(CO₃)₂ and Ca(NO₃)₂ 4H₂O are identified in a Greenland ice core. The chemical speciation of salts varies with past climatic conditions. Whereas the fraction of Na salts (NaCl + Na₂SO₄) exceeds that of Ca salts (CaSO₄+ CaCO₃) during the Holocene (0.6–11.7 kyr B.P.), the two fractions are similar during the Bølling-Allerød period (12.9–14.6 kyr B.P.). During cold climate such as over the Younger Dryas (12.0–12.6 kyr B.P.) and the Last Glacial Maximum (15.0–26.9 kyr B.P.), the fraction of Ca salts exceeds that of Na salts, showing that the most abundant ion generally controls the salt budget in each period. High-resolution analyses reveal changing particle compositions: those in Holocene ice show seasonal changes, and those in LGM ice show a difference between cloudy bands and clear layers, which again can be largely explained by the availability of ionic components in the atmospheric aerosol body of air masses reaching Greenland.
37. Decadal-scale progression of the onset of Dansgaard–Oeschger warming events
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Erhardt, Tobias, Capron, Emilie, Rasmussen, Sune Olander, Schüpbach, Simon, Bigler, Matthias, Adolphi, Florian, and Fischer, Hubertus
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13. Climate action ,530 Physics ,550 Earth sciences & geology - Abstract
During the last glacial period, proxy records throughout the Northern Hemisphere document a succession of rapid millennial-scale warming events, called Dansgaard–Oeschger (DO) events. A range of different mechanisms has been proposed that can produce similar warming in model experiments; however, the progression and ultimate trigger of the events are still unknown. Because of their fast nature, the progression is challenging to reconstruct from paleoclimate data due to the limited temporal resolution achievable in many archives and cross-dating uncertainties between records. Here, we use new high-resolution multi-proxy records of sea-salt (derived from sea spray and sea ice over the North Atlantic) and terrestrial (derived from the central Asian deserts) aerosol concentrations over the period 10–60 ka from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores in conjunction with local precipitation and temperature proxies from the NGRIP ice core to investigate the progression of environmental changes at the onset of the warming events at annual to multi-annual resolution. Our results show on average a small lead of the changes in both local precipitation and terrestrial dust aerosol concentrations over the change in sea-salt aerosol concentrations and local temperature of approximately one decade. This suggests that, connected to the reinvigoration of the Atlantic meridional overturning circulation and the warming in the North Atlantic, both synoptic and hemispheric atmospheric circulation changes at the onset of the DO warming, affecting both the moisture transport to Greenland and the Asian monsoon systems. Taken at face value, this suggests that a collapse of the sea-ice cover may not have been the initial trigger for the DO warming.
38. High-resolution mineral dust and sea ice proxy records from the Talos Dome ice core
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Kaufmann, Patrik, Federer, Urs, Schüpbach, Simon, Barbante, C., Albani, S., Stocker, Thomas, and Fischer, Hubertus
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13. Climate action ,530 Physics - Abstract
In this study we report on new non-sea salt calcium (nssCa2+, mineral dust proxy) and sea salt sodium (ssNa+, sea ice proxy) records along the East Antarctic Talos Dome deep ice core in centennial resolution reaching back 150 thousand years (ka) before present. During glacial conditions nssCa2+ fluxes in Talos Dome are strongly related to temperature as has been observed before in other deep Antarctic ice core records, and has been associated with synchronous changes in the main source region (southern South America) during climate variations in the last glacial. However, during warmer climate conditions Talos Dome mineral dust input is clearly elevated compared to other records mainly due to the contribution of additional local dust sources in the Ross Sea area. Based on a simple transport model, we compare nssCa2+ fluxes of different East Antarctic ice cores. From this multi-site comparison we conclude that changes in transport efficiency or atmospheric lifetime of dust particles do have a minor effect compared to source strength changes on the large-scale concentration changes observed in Antarctic ice cores during climate variations of the past 150 ka. Our transport model applied on ice core data is further validated by climate model data. The availability of multiple East Antarctic nssCa2+ records also allows for a revision of a former estimate on the atmospheric CO2 sensitivity to reduced dust induced iron fertilisation in the Southern Ocean during the transition from the Last Glacial Maximum to the Holocene (T1). While a former estimate based on the EPICA Dome C (EDC) record only suggested 20 ppm, we find that reduced dust induced iron fertilisation in the Southern Ocean may be responsible for up to 40 ppm of the total atmospheric CO2 increase during T1. During the last interglacial, ssNa+ levels of EDC and EPICA Dronning Maud Land (EDML) are only half of the Holocene levels, in line with higher temperatures during that period, indicating much reduced sea ice extent in the Atlantic as well as the Indian Ocean sector of the Southern Ocean. In contrast, Holocene ssNa+ flux in Talos Dome is about the same as during the last interglacial, indicating that there was similar ice cover present in the Ross Sea area during MIS 5.5 as during the Holocene.
39. High-resolution glacial and deglacial record of atmospheric methane by continuous-flow and laser spectrometer analysis along the NEEM ice core
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Mitchell, L. E., Chappellaz, L., Brook, E. J., Lee, J. E., Pascual, O., Blunier, T., Romanini, D., Rosen, J., Dallmayr, R., Baslev-Clausen, D., Stowasser, C., Schüpbach, Simon, and Faïn, X.
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13. Climate action ,530 Physics - Abstract
The Greenland NEEM (North Greenland Eemian Ice Drilling) operation in 2010 provided the first opportunity to combine trace-gas measurements by laser spectroscopic instruments and continuous-flow analysis along a freshly drilled ice core in a field-based setting. We present the resulting atmospheric methane (CH4) record covering the time period from 107.7 to 9.5 ka b2k (thousand years before 2000 AD). Companion discrete CH4 measurements are required to transfer the laser spectroscopic data from a relative to an absolute scale. However, even on a relative scale, the high-resolution CH4 data set significantly improves our knowledge of past atmospheric methane concentration changes. New significant sub-millennial-scale features appear during interstadials and stadials, generally associated with similar changes in water isotopic ratios of the ice, a proxy for local temperature. In addition to the midpoint of Dansgaard–Oeschger (D/O) CH4 transitions usually used for cross-dating, sharp definition of the start and end of these events brings precise depth markers (with ±20 cm uncertainty) for further cross-dating with other palaeo- or ice core records, e.g. speleothems. The method also provides an estimate of CH4 rates of change. The onsets of D/O events in the methane signal show a more rapid rate of change than their endings. The rate of CH4 increase associated with the onsets of D/O events progressively declines from 1.7 to 0.6 ppbv yr−1 in the course of marine isotope stage 3. The largest observed rate of increase takes place at the onset of D/O event #21 and reaches 2.5 ppbv yr−1.
40. Millennial changes in North American wildfire and soil activity over the last glacial cycle
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Wolff, Eric W., Mulvaney, Robert, Fischer, Hubertus, Gfeller, Gideon, Stocker, Thomas F., Röthlisberger, Regine, Erhardt, Tobias, Bigler, Matthias, and Schüpbach, Simon
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13. Climate action ,530 Physics - Abstract
Climate changes in the North Atlantic region during the last glacial cycle were dominated by the slow waxing and waning of the North American ice sheet as well as by intermittent, millennial-scale Dansgaard–Oeschger climate oscillations. However, prior to the last deglaciation, the responses of North American vegetation and biomass burning to these climate variations are uncertain. Ammonium in Greenland ice cores, a product from North American soil emissions and biomass burning events, can help to fill this gap. Here we use continuous, high-resolution measurements of ammonium concentrations between 110,000 to 10,000 years ago from the Greenland NGRIP and GRIP ice cores to reconstruct North American wildfire activity and soil ammonium emissions. We find that on orbital timescales soil emissions increased under warmer climate conditions when vegetation expanded northwards into previously ice-covered areas. For millennial-scale interstadial warm periods during Marine Isotope Stage 3, the fire recurrence rate increased in parallel to the rapid warmings, whereas soil emissions rose more slowly, reflecting slow ice shrinkage and delayed ecosystem changes. We conclude that sudden warming events had little impact on soil ammonium emissions and ammonium transport to Greenland, but did result in a substantial increase in the frequency of North American wildfires.
41. Geochemical and Microbiological Studies of Nitrous Oxide Variations within the New NEEM Greenland Ice Core During the Last Glacial Period
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Miteva, Vanya, Schüpbach, Simon, Sowers, Todd, Brenchley, Jean, and Fischer, Hubertus
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13. Climate action ,530 Physics - Abstract
Deep polar ice cores provide atmospheric records of nitrous oxide (N₂O) and other trace gases reflecting climate history along with a parallel archive of microbial cells transported with mineral dust, marine and volcanic aerosols from around the globe. Our interdisciplinary study of 32 samples from different depths of the recently drilled NEEM Greenland ice core addressed the question whether the identified microorganisms were capable of post-depositional biological production of N₂O in situ. We used high-resolution geochemical and microbiological approaches to examine the N₂O concentrations, the quantitative distributions of dust, Ca⁺², NH₄⁺ and NO₃⁻ ¡ons related to N cycle pathways, the microbial abundance and diversity at specific NEEM core depths from 1758 m to 1867.8 m. Results showed varying concentrations of N₂O (220 –271.5 ppb). Microbial abundance fluctuated between 3.3 x 10⁴ and 3.3 x 10⁶ cells mL⁻¹ in direct correlation with dust and Ca²⁺ concentrations with higher cell numbers deposited during colder periods. The average values of NH₄⁺ and NO₃⁻ indicated that substrates were available for the microorganisms capable of utilizing them. PCR amplification of selected functional genes involved in bacterial and archaeal nitrification and denitrification was not successful. Sanger and Illumina MiSeq sequence analyses of SSU rRNA genes showed variable representation of Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Actinobacteria, chloroplasts and fungi. The metabolic potential of the dominant genera of Proteobacteria and Firmicutes as possible N₂O producers suggested that denitrification activity may have led to in-situ production and accumulation of N₂O.
42. Boreal fire records in Northern Hemisphere ice cores: a review
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McConnell, Joseph, Fischer, Hubertus, Schüpbach, Simon, Chellman, Nathan, Leuenberger, Daiana, Arienzo, Monica, Flannigan, Mike, Sigl, Michael, Preunkert, Susanne, Wolff, Eric W., Place, Philip, Maselli, Olivia, and Legrand, Michel
- Subjects
13. Climate action ,530 Physics ,15. Life on land - Abstract
Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. pre-industrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species – potassium, nitrate, and carboxylates (except formate) – is complicated by either post-depositional effects or existence of large non-biomass-burning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of high-resolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region.
43. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene
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Schüpbach, Simon, Fischer, Hubertus, Bigler, M., Erhardt, Tobias, Gfeller, Gideon, Leuenberger, Daiana, Mini, Olivia, Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, Florian, Maselli, O., McConnell, J., and Wolff, E. W.
- Subjects
13. Climate action ,530 Physics ,complex mixtures - Abstract
The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
44. A new method for high-resolution methane measurements on polar ice cores using continuous flow analysis.
- Author
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Schüpbach S, Federer U, Kaufmann PR, Hutterli MA, Buiron D, Blunier T, Fischer H, and Stocker TF
- Subjects
- Antarctic Regions, Atmosphere chemistry, Calibration, Climate, Humans, Reproducibility of Results, Chromatography instrumentation, Chromatography methods, Environmental Monitoring methods, Fractionation, Field Flow instrumentation, Fractionation, Field Flow methods, Ice analysis, Methane analysis
- Abstract
Methane (CH4) is the second most important anthropogenic greenhouse gas in the atmosphere. Rapid variations of the CH4 concentration, as frequently registered, for example, during the last ice age, have been used as reliable time markers for the definition of a common time scale of polar ice cores. In addition, these variations indicate changes in the sources of methane primarily associated with the presence of wetlands. In order to determine the exact time evolution of such fast concentration changes, CH4 measurements of the highest resolution in the ice core archive are required. Here, we present a new, semicontinuous and field-deployable CH4 detection method, which was incorporated in a continuous flow analysis (CFA) system. In CFA, samples cut along the axis of an ice core are melted at a melt speed of typically 3.5 cm/min. The air from bubbles in the ice core is extracted continuously from the meltwater and forwarded to a gas chromatograph (GC) for high-resolution CH4 measurements. The GC performs a measurement every 3.5 min, hence, a depth resolution of 15 cm is achieved atthe chosen melt rate. An even higher resolution is not necessary due to the low pass filtering of air in ice cores caused by the slow bubble enclosure process and the diffusion of air in firn. Reproducibility of the new method is 3%, thus, for a typical CH4 concentration of 500 ppb during an ice age, this corresponds to an absolute precision of 15 ppb, comparable to traditional analyses on discrete samples. Results of CFA-CH4 measurements on the ice core from Talos Dome (Antarctica) illustrate the much higher temporal resolution of our method compared with established melt-refreeze CH4 measurements and demonstrate the feasibility of the new method.
- Published
- 2009
- Full Text
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