Modeling air movement and bubble trapping in firn

Trudinger, Cathy M.; Enting, I. G.; Etheridge, D. M.; Francey, R. J.; Levchenko, V.A.; Steele, L. P.; Raynaud, Dominique; Arnaud, Laurent

doi:10.1029/96jd03382

Cited by 152 publications

(224 citation statements)

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“…For high accumulation rate sites like DE08, the firn column does not reach equilibrium completely and there is a difference of 6% in the effect of gravity on N 2 and CO 2 , due to different rates of diffusion relative to ice advection [Trudinger et al, 1997], and the firn model is needed to quantify this.…”

Section: Corrections For Gravitational and Diffusion Fractionation 2mentioning

confidence: 99%

“…[59] For measurements of isotopic ratios in firn and ice air samples, a so-called diffusion correction is needed [Trudinger et al, 1997]. This correction arises from the fact that an isotope ratio is the ratio of two isotopes with slightly different diffusion coefficients and therefore slightly different effective ages [Trudinger, 2000, section 3.6].…”

Section: Diffusion Correctionmentioning

confidence: 99%

“…[37] We used the CSIRO firn model [Trudinger et al, 1997[Trudinger et al, , 2013] to date firn air and provide corrections for gravity and diffusion fractionation. For each site, we specify mean annual temperature, pressure, accumulation rate, the depth profile of firn density, profiles of closed and open porosity versus density, and we calibrate effective diffusivity (or, more accurately, inverse tortuosity) versus porosity to give optimum agreement between modeled and measured concentrations of tracers.…”

Section: Firn Modelmentioning

confidence: 99%

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A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

et al. 2013

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[1] We present new measurements of ı 13 C of CO 2 extracted from a high-resolution ice core from Law Dome (East Antarctica), together with firn measurements performed at Law Dome and South Pole, covering the last 150 years. Our analysis is motivated by the need to better understand the role and feedback of the carbon (C) cycle in climate change, by advances in measurement methods, and by apparent anomalies when comparing ice core and firn air ı 13 C records from Law Dome and South Pole. We demonstrate improved consistency between Law Dome ice, South Pole firn, and the Cape Grim (Tasmania) atmospheric ı 13 C data, providing evidence that our new record reliably extends direct atmospheric measurements back in time. We also show a revised version of early ı 13 C measurements covering the last 1000 years, with a mean preindustrial level of -6.50 . Finally, we use a Kalman Filter Double Deconvolution to infer net natural CO 2 fluxes between atmosphere, ocean, and land, which cause small ı 13 C deviations from the predominant anthropogenically induced ı 13 C decrease. The main features found from the previous ı 13 C record are confirmed, including the ocean as the dominant cause for the 1940 A.D. CO 2 leveling. Our new record provides a solid basis for future investigation of the causes of decadal to centennial variations of the preindustrial atmospheric CO 2 concentration. Those causes are of potential significance for predicting future CO 2 levels and when attempting atmospheric verification of recent and future global carbon emission mitigation measures through Coupled Climate Carbon Cycle Models.

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Section: Corrections For Gravitational and Diffusion Fractionation 2mentioning

confidence: 99%

Section: Diffusion Correctionmentioning

confidence: 99%

Section: Firn Modelmentioning

confidence: 99%

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A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

et al. 2013

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“…Greenland samples were collected at the NEEM (North Greenland Eemian Ice Drilling) site in 2008 (Buizert et al, 2012). The CSIRO firn model (Trudinger et al, 1997) was used to derive age spectra for the individual firn samples and more details on these samples and their analysis are given in Vollmer et al (2016Vollmer et al ( , 2018 and . A diffusion coefficient of HFC-23 relative to CO 2 of 0.797 was used (Fuller et al, 1966).…”

Section: Firn and Archived Airmentioning

confidence: 99%

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF<sub>3</sub>) and the link to HCFC-22 (CHClF<sub>2</sub>) production

et al. 2018

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Abstract. High frequency measurements of trifluoromethane (HFC-23, CHF 3 ), a potent hydrofluorocarbon greenhouse gas, largely emitted to the atmosphere as a by-product of the production of the hydrochlorofluorocarbon HCFC-22 (CHClF 2 ), at five core stations of the Advanced Global Atmospheric Gases Experiment (AGAGE) network, combined with measurements on firn air, old Northern Hemisphere air samples and Cape Grim Air Archive (CGAA) air samples, are used to explore the current and historic changes in the atmospheric abundance of HFC-23. These measurements are used in combination with the AGAGE 2-D atmospheric 12-box model and a Bayesian inversion methodology to determine model atmospheric mole fractions and the history of global HFC-23 emissions. The global modelled annual mole fraction of HFC-23 in the background atmosphere was 28.9 ± 0.6 pmol mol −1 at the end of 2016, representing a 28 % increase from 22.6 ± 0.4 pmol mol −1 in 2009. Over the same time frame, the modelled mole fraction of HCFC-22 increased by 19 % from 199 ± 2 to 237 ± 2 pmol mol −1 . However, unlike HFC-23, the annual average HCFC-22 growth rate slowed from 2009 to 2016 at an annual average rate of −0.5 pmol mol −1 yr −2 . This slowing atmospheric growth is consistent with HCFC-22 moving from dispersive (high fractional emissions) to feedstock (low fractional emissions) uses, with HFC-23 emissions remaining as a consequence of incomplete mitigation from all HCFC-22 production.Our results demonstrate that, following a minimum in HFC-23 global emissions in 2009 of 9.6 ± 0.6, emissions increased to a maximum in 2014 of 14.5 ± 0.6 Gg yr −1 and then declined to 12.7 ± 0.6 Gg yr −1 (157 Mt CO 2 eq. yr −1 ) in 2016. The 2009 emissions minimum is consistent with estimates based on national reports and is likely a response to the implementation of the Clean Development Mechanism (CDM) to mitigate HFC-23 emissions by incineration in developing (non-Annex 1) countries under the Kyoto Protocol. Our derived cumulative emissions of HFC-23 during 2010-2016 were 89 ± 2 Gg (1.1 ± 0.2 Gt CO 2 eq.), which led to an increase in radiative forcing of 1.0 ± 0.1 mW m −2 over the same period. Although the CDM had reduced global HFC-23 emissions, it cannot now offset the higher emissions from increasing HCFC-22 production in non-Annex 1 countries, as the CDM was closed to new entrants in 2009. We also find that the cumulative European HFC-23 emissions from 2010 to 2016 were ∼ 1.3 Gg, corresponding to just 1.5 % ofPublished by Copernicus Publications on behalf of the European Geosciences Union. The majority of the increase in global HFC-23 emissions since 2010 is attributed to a delay in the adoption of mitigation technologies, predominantly in China and East Asia. However, a reduction in emissions is anticipated, when the Kigali 2016 amendment to the Montreal Protocol, requiring HCFC and HFC production facilities to introduce destruction of HFC-23, is fully implemented.

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“…This may have significant effects on CH4 isotopic ratios when rapid atmospheric growth creates gradients in the CH4 mixing ratio in the fire, such as during the industrial period. Fractionation by both gravity and diffusion have been modeled by Trudinger et al [1997] and the corrections for each effect on the isotopic ratios and mixing ratios at DE08-2 have been determined.…”

Section: Air Enclosure and Chronologymentioning

confidence: 99%

Atmospheric methane between 1000 A.D. and present: Evidence of anthropogenic emissions and climatic variability

Etheridge¹,

Steele²,

Francey³

et al. 1998

J. Geophys. Res.

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Modeling air movement and bubble trapping in firn

Cited by 152 publications

References 30 publications

A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF<sub>3</sub>) and the link to HCFC-22 (CHClF<sub>2</sub>) production

Atmospheric methane between 1000 A.D. and present: Evidence of anthropogenic emissions and climatic variability

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Modeling air movement and bubble trapping in firn

Cited by 152 publications

References 30 publications

A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica

A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF&lt;sub&gt;3&lt;/sub&gt;) and the link to HCFC-22 (CHClF&lt;sub&gt;2&lt;/sub&gt;) production

Atmospheric methane between 1000 A.D. and present: Evidence of anthropogenic emissions and climatic variability

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A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

A revised 1000 year atmospheric δ¹³C‐CO₂ record from Law Dome and South Pole, Antarctica

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF<sub>3</sub>) and the link to HCFC-22 (CHClF<sub>2</sub>) production