Browsing by Author "Yver, C"

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    Estimation of the molecular hydrogen soil uptake and traffic emissions at a suburban site near Paris through hydrogen, carbon monoxide, and radon-222 semicontinuous measurements.
    (American Geophysical Union, 2009-09-23) Yver, C; Schmidt, M; Bousquet, P; Zahorowski, W; Ramonet, M
    Since June 2006, simultaneous semicontinuous measurements of tropospheric molecular hydrogen (H2), carbon monoxide (CO), and radon-222 (222Rn) have been performed at Gif-sur-Yvette (Paris region), a suburban atmospheric measurement site in France. Molecular hydrogen mixing ratios range from 500 to 1000 ppb, CO mixing ratios vary from 100 to 1400 ppb, and 222Rn concentrations fluctuate from 0 to 20 Bq m−3. The H2 seasonal cycle shows the expected pattern for the Northern Hemisphere with a maximum in spring and a minimum in autumn. We inferred a mean baseline value of 533 ppb with a peak-to-peak amplitude of 30 ppb. Carbon monoxide exhibits a seasonal cycle with a maximum in winter and a minimum in summer. The mean baseline value reaches 132 ppb with a peak-to-peak amplitude of 40 ppb. Radon-222 presents weak seasonal variations with a maximum in autumn/winter and a minimum in spring/summer. The diurnal cycles of H2 and CO are dominated by emissions from nearby traffic with two peaks during morning and evening rush hours. The typical H2/CO emission ratio from traffic is found to be 0.47 ± 0.08 on a molar basis (ppb/ppb). The radon tracer method is applied to nighttime H2 observations to estimate the H2 soil uptake of the nocturnal catchment area of our sampling site. The influences from nocturnal local anthropogenic combustion sources are estimated by parallel measurements of CO at 0.14 × 10−5 g(H2) m−2 h−1. The mean inferred dry deposition velocity is 0.024 ± 0.013 cm s−1 with a seasonal amplitude of 40% at Gif-sur-Yvette. © 2009, American Geophysical Union
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    Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions
    (European Geosciences Union, 2011-01-01) Zhang, K; Feichter, J; Kazil, J; Wan, H; Zhuo, W; Griffiths, AD; Sartorius, H; Zahorowski, W; Ramonet, M; Schmidt, M; Yver, C; Neubert, REM; Brunke, EG
    The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. Near-surface radon concentrations simulated with this new map compare well with measurements. Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. During cold seasons, at locations where high concentration of sulfuric acid gas and low temperature provide potentially favorable conditions for nucleation, the coexistence of high ionization rate may help enhance the particle formation processes. This suggests that it is probably worth investigating the impact of radon-induced ionization on aerosol-climate interaction in global models. © Author(s) 2011.