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| Titel |
Accurate mobile remote sensing of XCO2 and XCH4 latitudinal transects from aboard a research vessel |
| VerfasserIn |
F. Klappenbach, M. Bertleff, J. Kostinek, F. Hase, T. Blumenstock, A. Agusti-Panareda, M. Razinger, A. Butz |
| 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. 12 ; Nr. 8, no. 12 (2015-12-01), S.5023-5038 |
| Datensatznummer |
250116712
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| Publikation (Nr.) |
 copernicus.org/amt-8-5023-2015.pdf |
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| Zusammenfassung |
| A portable Fourier transform spectrometer (FTS), model EM27/SUN, was deployed
onboard the research vessel Polarstern to measure the column-average
dry air mole fractions of carbon dioxide (XCO2) and methane
(XCH4) by means of direct sunlight absorption spectrometry. We report
on technical developments as well as data calibration and reduction measures
required to achieve the targeted accuracy of fractions of a percent in
retrieved XCO2 and XCH4 while operating the instrument under
field conditions onboard the moving platform during a 6-week cruise on the Atlantic from Cape Town (South Africa, 34° S,
18° E; 5 March 2014) to Bremerhaven (Germany,
54° N, 19° E; 14 April 2014). We demonstrate
that our solar tracker typically achieved a tracking precision of better than
0.05° toward the center of the sun throughout the ship cruise
which facilitates accurate XCO2 and XCH4 retrievals even
under harsh ambient wind conditions. We define several quality filters that
screen spectra, e.g., when the field of view was partially obstructed by ship
structures or when the lines-of-sight crossed the ship exhaust plume. The
measurements in clean oceanic air, can be used to characterize a spurious
air-mass dependency. After the campaign, deployment of the spectrometer
alongside the TCCON (Total Carbon Column Observing Network) instrument at
Karlsruhe, Germany, allowed for determining a calibration factor that makes
the entire campaign record traceable to World Meteorological Organization
(WMO) standards. Comparisons to observations of the GOSAT satellite and
concentration fields modeled by the European Centre for Medium-Range Weather
Forecasts (ECMWF) Copernicus Atmosphere Monitoring Service (CAMS) demonstrate
that the observational setup is well suited to provide validation
opportunities above the ocean and along interhemispheric transects. |
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