Two decades of OH variability as inferred by an inversion of atmospheric transport and chemistry of methyl chloroform

Bousquet, P.; Hauglustaine, Didier; Peylin, Philippe; Carouge, C.; Ciais, Philippe

doi:10.5194/acp-5-2635-2005

Cited by 154 publications

(235 citation statements)

References 38 publications

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“…In this study, the errors are set to ±100% of the maximum flux in the grid cell over the inversion period for H 2 , ±1% of the flux for MCF (in order to constrain OH), CO, CH 4 and HCHO. The error of ±10% for OH concentrations is consistent with the differences between estimates of the OH concentrations of several studies (Krol et al, 2003;Prinn et al, 2005;Bousquet et al, 2005). Finally, the error on the initial concentrations of HCHO, MCF and H 2 is set at ±10%.…”

Section: General Settings Of Pyvar/lmdz-sacssupporting

confidence: 62%

“…Its concentration is estimated in the model in an indirect way: using methyl chloroform (CH 3 CCl 3 or MCF) which reacts only with OH and the sources of which are quantified with acceptable accuracy (Krol et al, 2003;Prinn et al, 2005;Bousquet et al, 2005). The adequacy of SACS with the chemistry model INCA (Interactive Chemistry and Aerosols) (Folberth et al, 2005) is evaluated in Pison et al (2009).…”

Section: General Settings Of Pyvar/lmdz-sacsmentioning

confidence: 99%

“…These errors are considered unbiased and Gaussian. The state vector contains the emission fluxes (here for H 2 ) and the average production of HCHO in each cell at an eight-day frequency, the average OH concentrations as described by Bousquet et al (2005) (four latitudinal bands) at the same frequency and the initial conditions for the concentrations (here of H 2 ). The eight-day frequency of the state vector is chosen as a compromise between a high time resolution and a reasonable computational time.…”

Section: General Settings Of Pyvar/lmdz-sacsmentioning

confidence: 99%

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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: General Settings Of Pyvar/lmdz-sacssupporting

confidence: 62%

Section: General Settings Of Pyvar/lmdz-sacsmentioning

confidence: 99%

Section: General Settings Of Pyvar/lmdz-sacsmentioning

confidence: 99%

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

et al. 2011

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“…Montzka et al (2011) inferred small interannual OH variability and trends (typical OH changes from year to year of less than 3 %) and attributed previously estimated large year-to-year OH variations before 1998 (e.g. Bousquet et al, 2005;Prinn et al, 2001) to overly large sensitivity of OH concentrations inferred from methyl chloroform measurements to uncertainties in the latter's emissions. However, Prinn et al (2005) also showed lower post-1998 OH variability that they attributed to the lack of strong post-1998 El Niño events.…”

Section: Oh Oxidationmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

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Abstract. The global methane (CH 4 ) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH 4 over the past decade. Emissions and concentrations of CH 4 are continuing to increase, making CH 4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH 4 sources that overlap geographically, and from the destruction of CH 4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (∼ biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models, inventories and data-driven approaches (including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations). . Top-down inversions consistently infer lower emissions in China (∼ 58 Tg CH 4 yr −1 , range 51-72, −14 %) and higher emissions in Africa (86 Tg CH 4 yr −1 , range 73-108, +19 %) than bottom-up values used as prior estimates. Overall, uncertainties for anthropogenic emissions appear smaller than those from natural sources, and the uncertainties on source categories appear larger for top-down inversions than for bottom-up inventories and models.The most important source of uncertainty on the methane budget is attributable to emissions from wetland and other inland waters. We show that the wetland extent could contribute 30-40 % on the estimated range for wetland emissions. Other priorities for improving the methane budget include the following: (i) the development of process-based models for inland-water emissions, (ii) the intensification of methane observations at local scale (flux measurements) to constrain bottom-up land surface models, and at regional scale (surface networks and satellites) to constrain top-down inversions, (iii) improvements in the estimation of atmospheric loss by OH, and (iv) improvements of the transport models integrated in top-down inversions.

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“…The role of the OH sink 3690 P. Bousquet et al: Source attribution of the changes in atmospheric methane for [2006][2007][2008] in atmospheric CH 4 variations may be significant Prinn et al, 2005;Rigby et al, 2008) but it is still controversial, given discrepancies in the magnitude of OH interannual variations computed by atmospheric chemistry models (∼1-3%, (Dentener et al, 2003;van Weele et al, 2009) or estimated by atmospheric inversions based on 1,1,1-trichloroethane (∼4-10%, Bousquet et al, 2005;Krol and Lelieveld, 2003;Prinn et al, 2001).…”

Section: Introductionmentioning

confidence: 99%