Heavy hydrogen in the stratosphere

Röckmann, Thomas; Rhee, Tae Siek; Engel, Andreas

doi:10.5194/acp-3-2015-2003

Cited by 65 publications

(74 citation statements)

References 31 publications

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“…Future inversions of H 2 sources and sinks should gain robustness by including observations of other networks but also by including observations of the deuterium enrichment of H 2 (δD of H 2 ), as shown in Rhee et al (2006); Price et al (2007). Several groups have produced δD observations (Gerst and Quay, 2001;Rahn et al, 2003;Röckmann et al, 2003;Rhee et al, 2006;Price et al, 2007). Within the EUROHYDROS project, δD observations from six sampling sites are available for the recent years (from 2006).…”

Section: Discussionmentioning

confidence: 99%

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

et al. 2011

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Abstract. This paper presents an analysis of the recent tropospheric molecular hydrogen (H 2 ) budget with a particular focus on soil uptake and European surface emissions. A variational inversion scheme is combined with observations from the RAMCES and EUROHYDROS atmospheric networks, which include continuous measurements performed between mid-2006 and mid-2009. Net H 2 surface flux, then deposition velocity and surface emissions and finally, deposition velocity, biomass burning, anthropogenic and N 2 fixationrelated emissions were simultaneously inverted in several scenarios. These scenarios have focused on the sensibility of the soil uptake value to different spatio-temporal distributions. The range of variations of these diverse inversion setsCorrespondence to: C. E. Yver

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Section: Discussionmentioning

confidence: 99%

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

et al. 2011

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“…Recently it has been established that stratospheric H 2 is enriched in deuterium (D) along with the decrease of CH 4 mixing ratios whilst the H 2 mixing ratios remain almost constant Rhee et al, 2006a;Röckmann et al, 2003). It appears that the D enrichment of H 2 is much stronger than the concomitant enrichment for CH 4 acompanying its destruction by OH, O( 1 D), and Cl radicals.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen isotope fractionation in the photolysis of formaldehyde

2008

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Abstract. Experiments investigating the isotopic fractionation in the formation of H 2 by the photolysis of CH 2 O under tropospheric conditions are reported and discussed. The deuterium (D) depletion in the H 2 produced is 500(±20)‰ with respect to the parent CH 2 O. We also observed that complete photolysis of CH 2 O under atmospheric conditions produces H 2 that has virtually the same isotope ratio as that of the parent CH 2 O. These findings imply that there must be a very strong concomitant isotopic enrichment in the radical channel (CH 2 O+hν→CHO+H) as compared to the molecular channel (CH 2 O+hν→H 2 +CO) of the photolysis of CH 2 O in order to balance the relatively small isotopic fractionation in the competing reaction of CH 2 O with OH. Using a 1-box photochemistry model we calculated the isotopic fractionation factor for the radical channel to be 0.22(±0.08), which is equivalent to a 780(±80)‰ enrichment in D of the remaining CH 2 O. When CH 2 O is in photochemical steady state, the isotope ratio of the H 2 produced is determined not only by the isotopic fractionation occurring during the photolytical production of H 2 (α m ) but also by overall fractionation for the removal processes of CH 2 O (α f ), and is represented by the ratio of α m /α f . Applying the isotopic fractionation factors relevant to CH 2 O photolysis obtained in the present study to the troposphere, the ratio of α m /α f varies from ∼0.8 to ∼1.2 depending on the fraction of CH 2 O that reacts with OH and that produces H 2 . This range of α m /α f can render the H 2 produced from the photochemical oxidation of CH 4 to be enriched in D (with respect to the original CH 4 ) by the factor of 1.2-1.3 as anticipated in the literature.

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“…Evidence of a substantial enrichment in the deuterium content of formaldehyde is from theoretical and box model considerations of the oxidative chain between hydrocarbons and formaldehyde [Gerst and Quay, 2001;Rahn et al, 2003;Röckmann et al, 2003;Feilberg et al, 2007;Pieterse et al, 2009]; direct observations of the enrichment in dD of stratospheric H 2 as a result of CH 4 oxidation [Rahn et al, 2003;Röckmann et al, 2003]; photochemical modeling of the dD of H 2 in the troposphere and stratosphere [Price et al, 2007;Mar et al, 2007]; and observations of formaldehyde enriched in deuterium up to 210‰ [Rice and Quay, 2009]. The photochemical enrichment of formaldehyde must be sufficient to overcome a −450‰ to −500‰ isotope effect occurring with the photolysis of formaldehyde [Feilberg et al, 2007;Rhee et al, 2008].…”

Section: Climatological Mean Distribution Of H 2 and Dd-hmentioning

confidence: 99%

“…This progress provides the necessary tools to characterize spatial and temporal trends in dD of H 2 , which complements ongoing measurements of the concentration of H 2 in the atmosphere and provides valuable information on the distributions of H 2 sources and sinks. Thus far, however, measurements of dD of H 2 in remote atmospheres are limited to a handful of data sets [Gerst and Quay, 2001;Rahn et al, 2003;Röckmann et al, 2003;Rhee et al, 2006]. Measurements characterizing temporal trends and the spatial distribution dD of H 2 , in particular, are lacking.…”

Section: Introductionmentioning

confidence: 99%

“…[4] Constraints to the global hydrogen budget are vastly improved by the global monitoring of H 2 concentrations [Khalil and Rasmussen, 1990;Novelli et al, 1999;Simmonds et al, 2000], development and application of global chemical transport models [Hauglustaine and Ehhalt, 2002;Sanderson et al, 2003;Price et al, 2007], and the use of the naturally occurring stable isotope tracer deutero-hydrogen (DH) Quay, 2000, 2001;Rahn et al, 2003;Röckmann et al, 2003;Rhee et al, 2006]. Stable isotopic analysis, in particular, makes use of the DH/H 2 ratio in H 2 to distinguish between sources and sinks.…”

Section: Introductionmentioning

confidence: 99%

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Meridional distribution of molecular hydrogen and its deuterium content in the atmosphere

Rice¹,

Quay²,

Stutsman³

et al. 2010

J. Geophys. Res.

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The atmospheric molecular hydrogen concentration and its deuterium abundance were measured in remote air samples collected onboard six Pacific Ocean ship transects between 37°N and 77°S during years 2001 through 2005. The data reveal a year‐round interhemispheric gradient in H2 concentration and isotopic composition with the extratropical Northern Hemisphere lower in H2 concentration by 17 ± 11 ppb and δD of H2 by 16 ± 12‰ than the Southern Hemisphere (95% confidence). On the basis of these snapshots, the interhemispheric gradient in δD was observed to be smallest in September through November, a time that experiences the largest gradient in concentration, and the largest in April, a time that has a small gradient in concentration. A simple hemispheric box model of the atmosphere indicates that, while the hemispheric asymmetry in soil sink of H2 is primarily responsible for the observed interhemispheric gradient in H2 concentration, the hemispheric difference in the δD of the H2 sources and sinks are equally responsible for the observed interhemispheric gradient in δD. Both the inverse correlation between interhemispheric H2 and δD gradients and their seasonal changes point to the importance of the H2 produced by photochemical sources. Comparisons with a three‐dimensional chemical transport model shows reasonable agreement with mean behavior in both variables and provides an accounting for H2 sources and sinks within ±15% without a dramatic change in the H2 budget. Anomalous H2 concentrations and δD in tropics and low‐latitude regions observed during the November–December 2001 meridional H2 and δD snapshot is thought to be a result of H2 emissions from biomass burning, possibly from continental Africa.

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Heavy hydrogen in the stratosphere

Cited by 65 publications

References 31 publications

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

Hydrogen isotope fractionation in the photolysis of formaldehyde

Meridional distribution of molecular hydrogen and its deuterium content in the atmosphere

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