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| Titel |
High-frequency urban measurements of molecular hydrogen and carbon monoxide in the United Kingdom |
| VerfasserIn |
A. Grant, K. F. Stanley, S. J. Henshaw, D. E. Shallcross, S. O'Doherty |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 10 ; Nr. 10, no. 10 (2010-05-25), S.4715-4724 |
| Datensatznummer |
250008472
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| Publikation (Nr.) |
 copernicus.org/acp-10-4715-2010.pdf |
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| Zusammenfassung |
| High-frequency measurements of atmospheric molecular hydrogen (H2) and
carbon monoxide (CO) were made at an urban site in the United Kingdom (UK)
from mid-December, 2008 until early March, 2009. Very few measurements of
H2 exist in the urban environment, particularly within the UK, but are
an essential component in the assessment of anthropogenic emissions of
H2 and to a certain extent CO. These data provide detailed information
on urban time-series, diurnal cycles as well as sources and sinks of both
H2 and CO at urban locations. High-frequency data were found to be
strongly influenced by local meteorological conditions of wind speed and
temperature. Diurnal cycles were found to follow transport frequency very
closely due to the sites proximity to major carriageways, consequently a
strong correlation was found between H2 and CO mole fractions.
Background subtracted mean and rush hour molar H2/CO emission ratios of
0.53±0.08 and 0.57±0.06 respectively, were calculated from
linear fitting of data. The scatter plot of all H2 and CO data
displayed an unusual two population pattern, thought to be associated with a
large industrial area 85 km to the west of the site. However, the definitive
source of this two branch pattern could not be fully elucidated. H2
emissions from transport in the UK were estimated to be 188±39 Gg H2/yr, with 8.1±2.3 Tg/yr of H2 produced from vehicle
emissions globally. H2 and CO deposition velocities were calculated
during stable night-time inversion events when a clear decay of both species
was observed. CO was found to have a much higher deposition velocity than
H2, 1.3±0.8×10−3 and 2.2±1.5×10−4 m s−1 (1σ) respectively, going against the law of
molecular diffusivity. The source of this unusual result was investigated,
however no conclusive explanation was found for increased loss of CO over
H2 during stable night time inversion events. |
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