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Papers by Jocelyn Turnbull

AGU Fall Meeting Abstracts, Dec 1, 2019

Boletín - Organización Meteorológica Mundial, 2020

Quaternary Science Reviews

... in trace gases, but occasionally even the precision of these instruments can seem like a blun... more ... in trace gases, but occasionally even the precision of these instruments can seem like a blunt tool for ... Attributes whose fields never change once assigned make suitable keys. ... Trace Gas Data Management” (Masarie and Tans 2003) is intended to serve as a starting point for new ...

Radiocarbon, 2013

A workshop on atmospheric radiocarbon measurements was held in conjunction with the 21st Internat... more A workshop on atmospheric radiocarbon measurements was held in conjunction with the 21st International Radiocarbon conference in July 2012. The main topics were intercomparison of measurements of 14 C in atmospheric CO 2 , the potential for use of gas standards for atmospheric 14 C measurements, reporting of uncertainties, and expansion of intercomparison activities to other atmospheric trace gases. This report documents the discussions and conclusions of this workshop.

The state of California is leading the United States by enacting legislation (AB-32) to reduce gr... more The state of California is leading the United States by enacting legislation (AB-32) to reduce greenhouse gas emissions to 1990 levels by 2020. The success of reduction efforts can be gauged with accurate emissions inventories and potentially verified with atmospheric measurements of greenhouse gases (GHGs) over time. Measurements of multiple GHGs and associated trace gas species in a specific region

The radiocarbon content of atmospheric CO2 (14CO2) varies due to a number of factors. After the n... more The radiocarbon content of atmospheric CO2 (14CO2) varies due to a number of factors. After the near-doubling of the 14CO2 loading in the early 1960s (due to atmospheric nuclear weapons testing), many studies examined the fate of this 'bomb 14C' to understand exchange processes of CO2 with the surface reservoirs. Today, however, the atmosphere and surface reservoirs are close to

Atmospheric Chemistry and Physics, 2019

Atmospheric carbon monoxide (CO) is a key player in global atmospheric chemistry and a regulated ... more Atmospheric carbon monoxide (CO) is a key player in global atmospheric chemistry and a regulated pollutant in urban areas. Oxidation of volatile organic compounds (VOCs) is an important component of the global CO budget and has also been hypothesized to contribute substantially to the summertime urban CO budget. In principle, stable isotopic analysis of CO could constrain the magnitude of this source. However, the isotopic signature of VOC-produced CO has not been well quantified, especially for the oxygen isotopes. We performed measurements of CO stable isotopes on air samples from two sites around Indianapolis, US, over three summers to investigate the isotopic signature of VOCproduced CO. One of the sites is located upwind of the city, allowing us to quantitatively remove the background air signal and isolate the urban CO enhancements. as well as the isotopic signature of these enhancements. In addition, we use measurements of 14 CO 2 in combination with the CO : CO 2 emission ratio from fossil fuels to constrain the fossil-fuelderived CO and thereby isolate the VOC-derived component of the CO enhancement. Combining these measurements and analyses, we are able to determine the carbon and oxygen isotopic signatures of CO derived from VOC oxidation as −32.8 ‰±0.5 ‰ and 3.6 ‰±1.2 ‰, respectively. Additionally, we analyzed CO stable isotopes for 1 year at Beech Island, South Carolina, US, a site thought to have large VOC-derived contributions to the summertime CO budget. The Beech Island results are consistent with isotopic signatures of VOC-derived CO determined from the Indianapolis data. This study represents the first direct determination of the isotopic signatures of VOC-derived CO and will allow for improved use of isotopes in constraining the global and regional CO budgets.

Elementa: Science of the Anthropocene, 2017

We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O) in air durin... more We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O) in air during the winters of 2013–14 and 2014–15 at tall tower sampling sites in and around Indianapolis, USA. A tower located upwind of the city was used to quantitatively remove the background CO signal, allowing for the first unambiguous isotopic characterization of the urban CO source and yielding 13CO of –27.7 ± 0.5‰ VPDB and C18O of 17.7 ± 1.1‰ VSMOW for this source. We use the tower isotope measurements, results from a limited traffic study, as well as atmospheric reaction rates to examine contributions from different sources to the Indianapolis CO budget. Our results are consistent with earlier findings that traffic emissions are the dominant source, suggesting a contribution of 96% or more to the overall Indianapolis wintertime CO emissions. Our results are also consistent with the hypothesis that emissions from a small fraction of vehicles without functional catalytic systems dominate the ...

Atmospheric Chemistry and Physics Discussions, 2016

We present 60 years of Δ¹⁴CO₂ measurements from Wel... more We present 60 years of Δ¹⁴CO₂ measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric…

Elementa: Science of the Anthropocene, 2017

To effectively address climate change, aggressive mitigation policies need to be implemented to r... more To effectively address climate change, aggressive mitigation policies need to be implemented to reduce greenhouse gas emissions. Anthropogenic carbon emissions are mostly generated from urban environments, where human activities are spatially concentrated. Improvements in uncertainty determinations and precision of measurement techniques are critical to permit accurate and precise tracking of emissions changes relative to the reduction targets. As part of the INFLUX project, we quantified carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4) emission rates for the city of Indianapolis by averaging results from nine aircraft-based mass balance experiments performed in November-December 2014. Our goal was to assess the achievable precision of the aircraft-based mass balance method through averaging, assuming constant CO2, CH4 and CO emissions during a three-week field campaign in late fall. The averaging method leads to an emission rate of 14,600 mol/s for CO2, assumed to be la...

Atmospheric Chemistry and Physics, 2016

We examine the utility of tree ring 14 C archives for detecting long-term changes in fossil CO 2 ... more We examine the utility of tree ring 14 C archives for detecting long-term changes in fossil CO 2 emissions from a point source. Trees assimilate carbon from the atmosphere during photosynthesis, in the process faithfully recording the average atmospheric 14 C content in each new annual tree ring. Using 14 C as a proxy for fossil CO 2 , we examine interannual variability over six years of fossil CO 2 observations between 2004-2005 and 2011-2012 from two trees growing near the Kapuni Gas Treatment Plant in rural Taranaki, New Zealand. We quantify the amount of variability that can be attributed to transport and meteorology by simulating constant point-source fossil CO 2 emissions over the observation period with the atmospheric transport model WindTrax. We compare model simulation results to observations and calculate the amount of change in emissions that we can detect with new observations over annual or multi-year time periods, given both the measurement uncertainty of 1ppm and the modelled variation in transport. In particular, we ask, what is the minimum amount of change in emissions that we can detect using this method, given a reference period of six years? We find that changes of 42 % or more could be detected in a new sample from one year at the same observation location or 22 % in the case of four years of new samples. This threshold is reduced and the method becomes more practical the more the size of the signal increases. For point sources 10 times larger than the Kapuni plant (a more typical size for power plants worldwide), it would be possible to detect sustained emissions changes on the order of 10 %, given suitable meteorology and observations.

AGU Fall Meeting Abstracts, Dec 1, 2019

Boletín - Organización Meteorológica Mundial, 2020

Quaternary Science Reviews

... in trace gases, but occasionally even the precision of these instruments can seem like a blun... more ... in trace gases, but occasionally even the precision of these instruments can seem like a blunt tool for ... Attributes whose fields never change once assigned make suitable keys. ... Trace Gas Data Management” (Masarie and Tans 2003) is intended to serve as a starting point for new ...

Radiocarbon, 2013

A workshop on atmospheric radiocarbon measurements was held in conjunction with the 21st Internat... more A workshop on atmospheric radiocarbon measurements was held in conjunction with the 21st International Radiocarbon conference in July 2012. The main topics were intercomparison of measurements of 14 C in atmospheric CO 2 , the potential for use of gas standards for atmospheric 14 C measurements, reporting of uncertainties, and expansion of intercomparison activities to other atmospheric trace gases. This report documents the discussions and conclusions of this workshop.

The state of California is leading the United States by enacting legislation (AB-32) to reduce gr... more The state of California is leading the United States by enacting legislation (AB-32) to reduce greenhouse gas emissions to 1990 levels by 2020. The success of reduction efforts can be gauged with accurate emissions inventories and potentially verified with atmospheric measurements of greenhouse gases (GHGs) over time. Measurements of multiple GHGs and associated trace gas species in a specific region

The radiocarbon content of atmospheric CO2 (14CO2) varies due to a number of factors. After the n... more The radiocarbon content of atmospheric CO2 (14CO2) varies due to a number of factors. After the near-doubling of the 14CO2 loading in the early 1960s (due to atmospheric nuclear weapons testing), many studies examined the fate of this 'bomb 14C' to understand exchange processes of CO2 with the surface reservoirs. Today, however, the atmosphere and surface reservoirs are close to

Atmospheric Chemistry and Physics, 2019

Atmospheric carbon monoxide (CO) is a key player in global atmospheric chemistry and a regulated ... more Atmospheric carbon monoxide (CO) is a key player in global atmospheric chemistry and a regulated pollutant in urban areas. Oxidation of volatile organic compounds (VOCs) is an important component of the global CO budget and has also been hypothesized to contribute substantially to the summertime urban CO budget. In principle, stable isotopic analysis of CO could constrain the magnitude of this source. However, the isotopic signature of VOC-produced CO has not been well quantified, especially for the oxygen isotopes. We performed measurements of CO stable isotopes on air samples from two sites around Indianapolis, US, over three summers to investigate the isotopic signature of VOCproduced CO. One of the sites is located upwind of the city, allowing us to quantitatively remove the background air signal and isolate the urban CO enhancements. as well as the isotopic signature of these enhancements. In addition, we use measurements of 14 CO 2 in combination with the CO : CO 2 emission ratio from fossil fuels to constrain the fossil-fuelderived CO and thereby isolate the VOC-derived component of the CO enhancement. Combining these measurements and analyses, we are able to determine the carbon and oxygen isotopic signatures of CO derived from VOC oxidation as −32.8 ‰±0.5 ‰ and 3.6 ‰±1.2 ‰, respectively. Additionally, we analyzed CO stable isotopes for 1 year at Beech Island, South Carolina, US, a site thought to have large VOC-derived contributions to the summertime CO budget. The Beech Island results are consistent with isotopic signatures of VOC-derived CO determined from the Indianapolis data. This study represents the first direct determination of the isotopic signatures of VOC-derived CO and will allow for improved use of isotopes in constraining the global and regional CO budgets.

Elementa: Science of the Anthropocene, 2017

We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O) in air durin... more We present measurements of CO mole fraction and CO stable isotopes (δ13CO and δC18O) in air during the winters of 2013–14 and 2014–15 at tall tower sampling sites in and around Indianapolis, USA. A tower located upwind of the city was used to quantitatively remove the background CO signal, allowing for the first unambiguous isotopic characterization of the urban CO source and yielding 13CO of –27.7 ± 0.5‰ VPDB and C18O of 17.7 ± 1.1‰ VSMOW for this source. We use the tower isotope measurements, results from a limited traffic study, as well as atmospheric reaction rates to examine contributions from different sources to the Indianapolis CO budget. Our results are consistent with earlier findings that traffic emissions are the dominant source, suggesting a contribution of 96% or more to the overall Indianapolis wintertime CO emissions. Our results are also consistent with the hypothesis that emissions from a small fraction of vehicles without functional catalytic systems dominate the ...

Atmospheric Chemistry and Physics Discussions, 2016

We present 60 years of Δ¹⁴CO₂ measurements from Wel... more We present 60 years of Δ¹⁴CO₂ measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric…

Elementa: Science of the Anthropocene, 2017

To effectively address climate change, aggressive mitigation policies need to be implemented to r... more To effectively address climate change, aggressive mitigation policies need to be implemented to reduce greenhouse gas emissions. Anthropogenic carbon emissions are mostly generated from urban environments, where human activities are spatially concentrated. Improvements in uncertainty determinations and precision of measurement techniques are critical to permit accurate and precise tracking of emissions changes relative to the reduction targets. As part of the INFLUX project, we quantified carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4) emission rates for the city of Indianapolis by averaging results from nine aircraft-based mass balance experiments performed in November-December 2014. Our goal was to assess the achievable precision of the aircraft-based mass balance method through averaging, assuming constant CO2, CH4 and CO emissions during a three-week field campaign in late fall. The averaging method leads to an emission rate of 14,600 mol/s for CO2, assumed to be la...

Atmospheric Chemistry and Physics, 2016

We examine the utility of tree ring 14 C archives for detecting long-term changes in fossil CO 2 ... more We examine the utility of tree ring 14 C archives for detecting long-term changes in fossil CO 2 emissions from a point source. Trees assimilate carbon from the atmosphere during photosynthesis, in the process faithfully recording the average atmospheric 14 C content in each new annual tree ring. Using 14 C as a proxy for fossil CO 2 , we examine interannual variability over six years of fossil CO 2 observations between 2004-2005 and 2011-2012 from two trees growing near the Kapuni Gas Treatment Plant in rural Taranaki, New Zealand. We quantify the amount of variability that can be attributed to transport and meteorology by simulating constant point-source fossil CO 2 emissions over the observation period with the atmospheric transport model WindTrax. We compare model simulation results to observations and calculate the amount of change in emissions that we can detect with new observations over annual or multi-year time periods, given both the measurement uncertainty of 1ppm and the modelled variation in transport. In particular, we ask, what is the minimum amount of change in emissions that we can detect using this method, given a reference period of six years? We find that changes of 42 % or more could be detected in a new sample from one year at the same observation location or 22 % in the case of four years of new samples. This threshold is reduced and the method becomes more practical the more the size of the signal increases. For point sources 10 times larger than the Kapuni plant (a more typical size for power plants worldwide), it would be possible to detect sustained emissions changes on the order of 10 %, given suitable meteorology and observations.