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Title:
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An intercomparison ring test of ambient methane concentration measurements
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Author(s):
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Published by:
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Publication date:
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ECN
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1997
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ECN report number:
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Document type:
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ECN-C--97-086
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ECN publication
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Number of pages:
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Full text:
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17
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Download PDF
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Abstract:
Within the framework of the second phase of the Dutch National ResearchProgramme on Climate Change, ambient methane concentration measurements were
performed at five stations in the Netherlands by three different institutes.
These measurements are used in model calculations to derive emissions
estimates for the Netherlands and NW-Europe. The measurements were made by
using gas chromatography with slightly different techniques per institute. In
order to be able to use the data from the three institutes in the models an
intercalibration study was performed to correct the data to one scale, as all
institutes deploy different calibration standards. Derivation of one
correction factor by combining the different comparisons is difficult. If one
chooses the internationally most used NOAA scale then the results of KEMA in
the last ring test can be converted from NIST to NOAA scale by applying a
factor of 0.975, which is very close to the NIST to NOAA correction factor of
0.979 found earlier between three European institutes. The TNO data can be
converted from NMI to NOAA scale by applying a factor between 0.989 and
0.972. When one combined factor is chosen for TNO and KEMA then 0.979 would
be the best possible value as this is also the value found for the different
methods used by ECN and two other European institutes in an earlier
independent ring test. Then the results of the three different institutes are
comparable within 1% (20 ppbv). 6 tabs., 6 refs.
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