ECN publication
An intercomparison ring test of ambient methane concentration measurements
Published by: Publication date:
ECN 1997
ECN report number: Document type:
ECN-C--97-086 ECN publication
Number of pages: Full text:
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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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