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| Titel |
Validation of farm-scale methane emissions using nocturnal boundary layer budgets |
| VerfasserIn |
J. Stieger, I. Bamberger, N. Buchmann, W. Eugster |
| 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 ; 15, no. 24 ; Nr. 15, no. 24 (2015-12-21), S.14055-14069 |
| Datensatznummer |
250120239
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| Publikation (Nr.) |
 copernicus.org/acp-15-14055-2015.pdf |
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| Zusammenfassung |
| This study provides the first experimental validation of Swiss agricultural methane emission estimates at the farm scale. We
measured CH4 concentrations at a Swiss farmstead during two intensive field campaigns in August 2011 and July 2012 to
(1) quantify the source strength of livestock methane emissions using a tethered balloon system and (2) to validate inventory
emission estimates via nocturnal boundary layer (NBL) budgets. Field measurements were performed at a distance of 150 m from
the nearest farm buildings with a tethered balloon system in combination with gradient measurements at eight heights on
a 10 m tower to better resolve the near-surface concentrations. Vertical profiles of air temperature, relative humidity,
CH4 concentration, wind speed, and wind direction showed that the NBL was strongly influenced by local transport
processes and by the valley wind system. Methane concentrations showed a pronounced time course, with highest concentrations in
the second half of the night. NBL budget flux estimates were obtained via a time–space kriging approach. Main uncertainties of
NBL budget flux estimates were associated with nonstationary
atmospheric conditions and the estimate of the inversion height
zi (top of volume integration). The mean NBL budget fluxes of 1.60 ± 0.31 μg CH4 m-2 s-1
(1.40 ± 0.50 and 1.66 ± 0.20 μg CH4 m-2 s-1 in 2011 and 2012 respectively) were in good agreement
with local inventory estimates based on current livestock number and default emission factors, with 1.29 ± 0.47 and
1.74 ± 0.63 μg CH4 m-2 s-1 for 2011 and 2012 respectively. This indicates that emission factors used
for the national inventory reports are adequate, and we conclude that the NBL budget approach is a useful tool to validate
emission inventory estimates. |
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