ORCID Profile
0000-0002-9905-2446
Current Organisation
Météo-France
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Publisher: Copernicus GmbH
Date: 16-01-2020
Abstract: Abstract. In the 1990's, closed and open porosity volumes of firn s les have been measured by J.-M. Barnola using the technique of gas pycnometry, on firn from three different polar sites. They are the basis of a parameterization of closed porosity in polar firn, first introduced in Goujon et al. (2003) and used in several firn physics models (e.g. Buizert et al., 2012). However, these data and their processing have not been published in their own right yet. In this short article, we detail how they were processed by J.-M. Barnola, and how the closed porosity parameterization was obtained. We show that the original data processing only partially accounts for the presence of re-opened bubbles in the s les. Since the proper correction to apply for this effect is hard to estimate, we also processed the data without including a correction for re-opened bubbles. Finally, we intend to make these pycnometry data available, in order to be used by the glaciology community, notably for the study of polar ice formation and of the composition of gas records in ice cores. They are hosted on the PANGAEA database: doi.pangaea.de/10.1594/PANGAEA.907678 (Fourteau et al., 2019a).
Publisher: Copernicus GmbH
Date: 20-05-2020
DOI: 10.5194/ESSD-12-1171-2020
Abstract: Abstract. In the 1990s, closed and open porosity volumes of firn s les were measured by J.-M. Barnola using the technique of gas pycnometry, on firn from three different polar sites. They are the basis of a parameterization of closed porosity in polar firn, first introduced in Goujon et al. (2003) and used in several firn physics models (e.g., Buizert et al., 2012). However, these data and their processing have not been published in their own right yet. In this short article, we detail how they were processed by J.-M. Barnola and how the closed porosity parameterization was obtained. We show that the original data processing only partially accounts for the presence of reopened bubbles in the s les. Since the proper correction to apply for this effect is hard to estimate, we also processed the data without including a correction for reopened bubbles. Finally, we made these pycnometry data available in order to be used by the glaciology community, notably for the study of polar ice formation and of the composition of gas records in ice cores. They are hosted on the PANGAEA database: 0.1594/PANGAEA.907678 (Fourteau et al., 2019a).
Publisher: Copernicus GmbH
Date: 21-04-2023
DOI: 10.5194/CP-2023-9
Abstract: Abstract. Carbon monoxide (CO) is a naturally occurring atmospheric trace gas, a regulated pollutant and one of the main components determining the oxidative capacity of the atmosphere. Evaluating climate-chemical models under different conditions than today and constraining past CO sources requires a reliable record of atmospheric CO mixing ratios ([CO]) since pre-industrial times. Here, we report the first continuous record of atmospheric [CO] for Southern Hemisphere (SH) high latitudes over the past three millennia. Our continuous record is a composite of three high-resolution Antarctic ice core gas records and firn air measurements from seven Antarctic locations. The ice core gas [CO] records were measured by continuous flow analysis (CFA) using an optical-feedback cavity-enhanced absorption spectrometer (OF-CEAS), achieving excellent external precision (2.8–8.8 ppbv, 2σ), and consistently low blanks (ranging from 4.1 ± 1.2 to 7.4 ± 1.4 ppbv), enabling paleo-atmospheric interpretations. Six new firn air [CO] Antarctic datasets collected between 1993 and 2016 CE at the DE08-2, DSSW19K, DSSW20K, South Pole, ABN, and Lock-In sites (and one previously published firn CO dataset at Berkner) were used to reconstruct the atmospheric history of CO from ~1897 CE using inverse modeling that incorporates the influence of gas transport in firn. Excellent consistency was observed between the youngest ice core gas [CO] and the [CO] from the base of the firn, and between the recent firn [CO] and atmospheric [CO] measurements at Mawson station (East Antarctica), yielding a consistent and contiguous record of CO across these different archives. Our Antarctic [CO] record is relatively stable from −835 to 1500 CE with mixing ratios within a 30–45 ppbv range (2σ). There is a ~5 ppbv decrease in [CO] to a minimum at around 1700 CE, during the Little Ice Age. CO mixing ratios then increase over time to reach a maximum of ~54 ppbv by ~1985 CE. Most of the industrial period [CO] growth occurred between about 1940 to 1985 CE, after which there was an overall [CO] decrease, as observed at atmospheric monitoring sites around the world and in Greenland firn air. Our Antarctic ice core gas CO observations differ from previously published records in two key aspects. First, our mixing ratios are significantly lower than reported previously, suggesting previous studies underestimated blank contributions. Second, our new CO record does not show a maximum in the late 1800s. The absence of CO peak around the turn of the century argues against there being a peak in Southern Hemisphere biomass burning at this time, which is in agreement with (i) other paleofire proxies such as ethane or acetylene and (ii) conclusions reached by paleofire modeling. The combined ice core and firn air CO history, spanning −835–1992 CE, extended to the present day by the Mawson atmospheric record, provides a useful benchmark for future atmospheric chemistry modeling studies.
Publisher: Copernicus GmbH
Date: 21-04-2023
Location: No location found
No related grants have been discovered for Kévin Fourteau.