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| Titel |
Calibration and instrumental line shape characterization of a set of portable FTIR spectrometers for detecting greenhouse gas emissions |
| VerfasserIn |
M. Frey, F. Hase, T. Blumenstock, J. Gross, M. Kiel, G. Mengistu Tsidu, K. Schäfer, M. K. Sha, J. Orphal |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 7 ; Nr. 8, no. 7 (2015-07-31), S.3047-3057 |
| Datensatznummer |
250116496
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| Publikation (Nr.) |
 copernicus.org/amt-8-3047-2015.pdf |
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| Zusammenfassung |
| A comprehensive calibration procedure for mobile, low-resolution,
solar-absorption FTIR spectrometers, used for greenhouse gases observations,
is developed. These instruments commend themselves for campaign use and
deployment at remote sites. The instrumental line shape (ILS) of each
spectrometer has been thoroughly characterized by analyzing the shape of
H2O signatures in open path spectra. A setup for the external source
is suggested and the invariance of derived ILS parameters with regard to
chosen path length is demonstrated. The instrumental line shape
characteristics of all spectrometers were found to be close to nominal.
Side-by-side solar observations before and after a campaign, which involved
shipping of all spectrometers to a selected target site and back, are applied
for verifying the temporal invariability of instrumental characteristics and
for deriving intercalibration factors for XCO2 and XCH4,
which take into account residual differences of instrumental characteristics.
An excellent level of agreement and stability was found between the different
spectrometers: the uncorrected biases in XCO2 and XCH4 are
smaller than 0.01 and 0.15 %, respectively, and the drifts are
smaller than 0.005 and 0.035 %. As an additional sensitive
demonstration of the instrumental performance we show the excellent agreement
of ground pressure values obtained from the total column measurements of
O2 and barometric records. We find a calibration factor of 0.9700 for
the spectroscopic measurements in comparison to the barometric records and a
very small scatter between the individual spectrometers (0.02 %). As
a final calibration step, using a co-located TCCON (Total Carbon Column Observation
Network) spectrometer as a
reference, a common scaling factor has been derived for the XCO2 and
XCH4 products, which ensures that the records are traceable to the
WMO in situ scale. |
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