Simulations of cosmogenic 14CO using the three‐dimensional atmospheric model MATCH: Effects of 14C production distribution and the solar cycle

Jöckel, Patrick; Lawrence, Mark G.; Brenninkmeijer, Carl A. M.

doi:10.1029/1999jd900061

Cited by 32 publications

(32 citation statements)

References 38 publications

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“…The relative spatial modulation of the 14 C production rate distribution in the atmosphere during a solar cycle has only a small effect on the relative distribution of 14 CO in the troposphere, as shown previously [ Jöckel et al , 1999]. Yet, the atmospheric 14 CO abundance does not respond instantaneously to changes in the source strength of 14 CO.…”

Section: Variation With Solar Activitysupporting

confidence: 55%

“…The focus of the present study is on the role of the solar cycle for the 14 CO methodology, in particular for the global source strength of 14 CO. This work is the third (and lacking) piece in line of two previously published articles about the source distribution and its variation with solar activity [ Jöckel et al , 1999], and the atmospheric response time to changes in the 14 CO source strength [ Jöckel et al , 2000]. …”

Section: Introductionmentioning

confidence: 99%

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The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

Jöckel

Brenninkmeijer

2002

J.‐Geophys.‐Res.

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[1] Mainly three processes determine the 14 CO content of the troposphere: the cosmogenic production of 14 C throughout the atmosphere, the removal (oxidation) by the hydroxyl radical (OH), and the transport of 14 CO from the stratosphere into the troposphere. These characteristics make 14 CO an interesting tracer for application in atmospheric dynamics and chemistry research. If 14 CO observations from different times have to be compared for changes in OH or the stratosphere-troposphere exchange (STE), the varying global source strength of 14 CO caused by variations in solar activity has to be taken into account. Three approaches for parameterizing solar activity with respect to the effect on the global average atmospheric 14 CO production rate are developed and compared. These methods involve the sunspot number, the heliospheric potential, and atmospheric neutron monitor data. Applying further results from previous studies about the atmospheric response, a rescaling procedure for 14 CO observations of different epochs to the same solar activity conditions is derived. All three approaches yield consistent results, whereby small differences provide an uncertainty estimate. The rescaling is used to compile the first solar cycle adjusted, zonalaverage 14 CO climatology (cosmogenic contribution) from all currently available 14 CO observations at the surface level. For this, in a first step, the smaller contribution of 14 CO of noncosmogenic, that is, biogenic origin (secondary source) is estimated from CO observations and subtracted from the measurements. The resulting climatology can be used to trace changes if compared to future observations, and especially for the evaluation of OH distributions and the stratosphere-troposphere exchange in three-dimensional global atmospheric models.

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Section: Variation With Solar Activitysupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

Jöckel

Brenninkmeijer

2002

J.‐Geophys.‐Res.

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“…In local winter, a high latitude reservoir of tropospheric 14 CO builds up due to low OH and downward transport from the production region in the stratosphere and upper troposphere Jöckel et al, 1999;Mak and Southon, 1998). Patches of air from this polar reservoir are transported equator-ward.…”

Section: Model Descriptionmentioning

confidence: 99%

What can 14CO measurements tell us about OH?

et al. 2008

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Abstract. The possible use of 14 CO measurements to constrain hydroxyl radical (OH) concentrations in the atmosphere is investigated. 14 CO is mainly produced in the upper atmosphere from cosmic radiation. Measurements of 14 CO at the surface show lower concentrations compared to the upper atmospheric source region, which is the result of oxidation by OH. In this paper, the sensitivity of 14 CO mixing ratio surface measurements to the 3-D OH distribution is assessed with the TM5 model. Simulated 14 CO mixing ratios agree within a few molecules 14 CO cm −3 (STP) with existing measurements at five locations worldwide. The simulated cosmogenic 14 CO distribution appears mainly sensitive to the assumed upper atmospheric 14 C source function, and to a lesser extend to model resolution. As a next step, the sensitivity of 14 CO measurements to OH is calculated with the adjoint TM5 model. The results indicate that 14 CO measurements taken in the tropics are sensitive to OH in a spatially confined region that varies strongly over time due to meteorological variability. Given measurements with an accuracy of 0.5 molecules 14 CO cm −3 STP, a good characterization of the cosmogenic 14 CO fraction, and assuming perfect transport modeling, a single 14 CO measurement may constrain OH to 0.2-0.3×10 6 molecules OH cm −3 on time scales of 6 months and spatial scales of 70×70 degrees (latitude×longitude) between the surface and 500 hPa. The sensitivity of 14 CO measurements to high latitude OH is about a factor of five higher. This is in contrast with methyl chloroform (MCF) measurements, which show the highest sensitivity to tropical OH, Correspondence to: M. C. Krol (m.c.krol@uu.nl) mainly due to the temperature dependent rate constant of the MCF-OH reaction. A logical next step will be the analysis of existing 14 CO measurements in an inverse modeling framework. This paper presents the required mathematical framework for such an analysis.

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“…4.12). One reason for higher 14 C content in the stratosphere during the post-bomb period is that most cosmogenic production of 14 C occurs in the stratosphere (O'Brien 1979;Jöckel 1999). While the natural stratosphere-troposphere gradient was amplified by the input of bomb 14 C, the stratosphere-troposphere gradient has been positive throughout history due to this effect.…”

Section: Stratospherementioning

confidence: 94%

Radiocarbon in the Atmosphere

Turnbull

Graven

Krakauer

2016

Radiocarbon and Climate Change

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Simulations of cosmogenic ¹⁴CO using the three‐dimensional atmospheric model MATCH: Effects of ¹⁴C production distribution and the solar cycle

Cited by 32 publications

References 38 publications

The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

What can <sup>14</sup>CO measurements tell us about OH?

Radiocarbon in the Atmosphere

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Simulations of cosmogenic 14CO using the three‐dimensional atmospheric model MATCH: Effects of 14C production distribution and the solar cycle

Cited by 32 publications

References 38 publications

The seasonal cycle of cosmogenic 14CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

The seasonal cycle of cosmogenic 14CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

What can &lt;sup&gt;14&lt;/sup&gt;CO measurements tell us about OH?

Radiocarbon in the Atmosphere

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Simulations of cosmogenic ¹⁴CO using the three‐dimensional atmospheric model MATCH: Effects of ¹⁴C production distribution and the solar cycle

The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

The seasonal cycle of cosmogenic ¹⁴CO at the surface level: A solar cycle adjusted, zonal‐average climatology based on observations

What can <sup>14</sup>CO measurements tell us about OH?