A process-based &amp;lt;sup&amp;gt;222&amp;lt;/sup&amp;gt;Rn flux map for Europe and its comparison to long-term observations

Karstens, Ute; Schwingshackl, Clemens; Schmithüsen, Dominik; Levin, Ingeborg

doi:10.5194/acpd-15-17397-2015

Cited by 11 publications

(11 citation statements)

References 42 publications

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“…Simulations of 222 Rn are intended to study vertical and synopticscale transport (Jacob et al, 1997); SF 6 is used to diagnose IH transport, stratosphere-troposphere exchange, and stratospheric AoA; E90 is used to diagnose the "chemical" tropopause and will be compared to Prather et al (2011). Note that we also included a 222 Rn simulation with monthly varying emissions over Europe during 2006-2010, based on the high-resolution emission maps presented in Karstens et al (2015). The current paper will, however, not analyse these simulations.…”

Section: Surfacementioning

confidence: 99%

“…Here, we include two offline versions of LMDZ -LMDZ3 and LMDZ5A -, both with a horizontal resolution of 1.875 • (latitude) ×3.75 • (longitude) and a vertical resolution of 39 hybrid sigma-pressure levels, commonly chosen for global inverse studies using LMDZ (Chevallier, 2015;Locatelli et al, 2015b;Yin et al, 2017). These two versions are different in terms of the physical parameterisation of deep convection and boundary layer mix- (Karstens et al, 2015 SF 6 SF 6 tracer, similar to Patra et al (2011), but with updated yearly emissions (Table 3) …”

Section: Lmdzmentioning

confidence: 99%

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Age of air as a diagnostic for transport timescales in global models

et al. 2018

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Abstract. This paper presents the first results of an age-ofair (AoA) inter-comparison of six global transport models. Following a protocol, three global circulation models and three chemistry transport models simulated five tracers with boundary conditions that grow linearly in time. This allows for an evaluation of the AoA and transport times associated with inter-hemispheric transport, vertical mixing in the troposphere, transport to and in the stratosphere, and transport of air masses between land and ocean. Since AoA is not a directly measurable quantity in the atmosphere, simulations of 222 Rn and SF 6 were also performed. We focus this first analysis on averages over the period 2000-2010, taken from longer simulations covering the period 1988-2014. We find that two models, NIES and TOMCAT, show substantially slower vertical mixing in the troposphere compared to other models (LMDZ, TM5, EMAC, and ACTM). However, while the TOMCAT model, as used here, has slow transport between the hemispheres and between the atmosphere over land and ocean, the NIES model shows efficient horizontal mixing and a smaller latitudinal gradient in SF 6 compared to the other models and observations. We find consistent differences between models concerning vertical mixing of the troposphere, expressed as AoA differences and modelled 222 Rn gradients between 950 and 500 hPa. All models agree, however, on an interesting asymmetry in inter-hemispheric mixing, with faster transport from the Northern Hemisphere surface to the Southern Hemisphere than vice versa. This is attributed to a rectifier effect caused by a stronger seasonal cycle in boundary layer venting over Northern Hemispheric land masses, and possibly to a related asymmetric position of the intertropical convergence zone. The calculated AoA in the mid-upper stratosphere varies considerably among the models (4-7 years). Finally, we find that the inter-model differences are generally larger than differences in AoA that result from using the same model with a different resolution or convective parameterisation. Taken together, the AoA model inter-comparison provides a useful addition to traditional approaches to evaluate transport timescales. Results highlight that inter-model differences associated with resolved transport (advection, reanalysis data, nudging) and parameterised transport (convection, boundary layer mixing) are still large and require further analysis. For this purpose, all model output and analysis software are available.

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Section: Surfacementioning

confidence: 99%

Section: Lmdzmentioning

confidence: 99%

Age of air as a diagnostic for transport timescales in global models

et al. 2018

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“…The mean ratio of the spatial variability within the extracted area (300 km × 300 km region centered on the Puy de Dôme station) to the mean flux is 30 % (Karstens et al, 2015, andU. Karstens andI.…”

Section: Uncertaintiesmentioning

confidence: 99%

Three years of semicontinuous greenhouse gas measurements at the Puy de Dôme station (central France)

et al. 2015

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Abstract. Three years of greenhouse gas measurements, obtained using a gas chromatograph (GC) system located at the Puy de Dôme station at 1465 m a.s.l. in central France, are presented. The GC system was installed in 2010 at Puy de Dôme and was designed for automatic and accurate semicontinuous measurements of atmospheric carbon dioxide, methane, nitrous oxide and sulfur hexafluoride mole fractions. We present in detail the instrumental setup and the calibration strategy, which together allow the GC to reach repeatabilities of 0.1 µmol mol −1 , 1.2 nmol mol −1 , 0.3 nmol mol −1 and 0.06 pmol mol −1 for CO 2 , CH 4 , N 2 O and SF 6 , respectively. The analysis of the 3-year atmospheric time series revealed how the planetary boundary layer height drives the mole fractions observed at a mountain site such as Puy de Dôme where air masses alternate between the planetary boundary layer and the free troposphere.Accurate long-lived greenhouse gas measurements collocated with 222 Rn measurements as an atmospheric tracer allowed us to determine the CO 2 , CH 4 and N 2 O emissions in the catchment area of the station. The derived CO 2 surface flux revealed a clear seasonal cycle, with net uptake by plant assimilation in the spring and net emission caused by the biosphere and burning of fossil fuel during the remainder of the year. We calculated a mean annual CO 2 flux of 1310 ± 680 t CO 2 km −2 . The derived CH 4 and N 2 O emissions in the station catchment area were 7.0 ± 4.0 t CH 4 km −2 yr −1 and 1.8 ± 1.0 t N 2 O km −2 yr −1 , respectively. Our derived annual CH 4 flux is in agreement with the national French inventory, whereas our derived N 2 O flux is 5 times larger than the same inventory.

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“…Rn simulation with monthly varying emissions over Europe during 2006-2010, based on the high resolution emissions maps presented in Karstens et al (2015). The current paper will, however, not analyse these simulations. )…”

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confidence: 99%

Age of Air as a diagnostic for transport time-scales in global models

Krol¹,

Bruine²,

Killaars³

et al. 2017

Preprint

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Abstract. This paper presents the first results of an age of air (AoA) inter-comparison of six global transport models. Following a protocol, three global circulation models and three chemistry transport models simulated five tracers with boundary conditions that grow linearly in time. This allows for an evaluation of the AoA and transport times associated with inter-hemispheric transport, vertical mixing in the troposphere, transport to and in the stratosphere, and transport of air masses between land and ocean. Since AoA is not a directly measurable quantity in the atmosphere, simulations of 222 Rn and SF 6 were also requested. 5We focus this first analysis on averages over the period 2000-2010, taken from longer simulations covering the 1988 -2014 period. We find that two models, NIES and TOMCAT, show substantially slower vertical mixing in the troposphere compared to other models (LMDZ, TM5, EMAC, and ACTM). However, while the TOMCAT model, as used here, has slow transport between the hemispheres and between land and ocean, the NIES model shows efficient horizontal mixing and a smaller latitudinal gradient in SF 6 compared to the other models and observations. We find consistent differences between models concerning 10 vertical mixing of the troposphere, expressed as AoA differences and modeled 222Rn gradients between 950 and 500 hPa.All models agree, however, on an interesting asymmetry in inter-hemispheric mixing, with faster transport from the Northern hemisphere surface to the Southern hemisphere than vice versa. This is attributed to a rectifier caused by a stronger seasonal cycle in boundary layer venting over Northern hemispheric landmasses, and possibly to a related asymmetric position of the inter-tropical convergence zone. The calculated AoA in the upper stratosphere varies considerably among the models (4 -7 15 years). Finally, we find that the inter-model differences are generally larger than differences in AoA that result from using the same model with a different resolution or convective parameterisation. Taken together, the AoA model inter-comparison provides a useful addition to traditional approaches to evaluate transport time scales. Results highlight that inter-model differences 1 Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2017-262 Manuscript under review for journal Geosci. Model Dev. Discussion started: 7 November 2017 c Author(s) 2017. CC BY 4.0 License. associated with resolved transport (advection) and parameterised transport (convection, boundary layer mixing) are still large, and require further analysis. For this purpose, all model output and analysis software is available.

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A process-based <sup>222</sup>Rn flux map for Europe and its comparison to long-term observations

Cited by 11 publications

References 42 publications

Age of air as a diagnostic for transport timescales in global models

Age of air as a diagnostic for transport timescales in global models

Three years of semicontinuous greenhouse gas measurements at the Puy de Dôme station (central France)

Age of Air as a diagnostic for transport time-scales in global models

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