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| Titel |
Tropospheric CH4 signals as observed by NDACC FTIR at globally distributed sites and comparison to GAW surface in situ measurements |
| VerfasserIn |
E. Sepúlveda, M. Schneider, F. Hase, S. Barthlott, D. Dubravica, O. E. García, A. Gomez-Pelaez, Y. González, J. C. Guerra, M. Gisi, R. Kohlhepp, S. Dohe, T. Blumenstock, K. Strong, D. Weaver, M. Palm, A. Sadeghi, N. M. Deutscher, T. Warneke, J. Notholt, N. Jones, D. W. T. Griffith, D. Smale, G. W. Brailsford, J. Robinson, F. Meinhardt, M. Steinbacher, T. Aalto, D. Worthy |
| 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 ; 7, no. 7 ; Nr. 7, no. 7 (2014-07-31), S.2337-2360 |
| Datensatznummer |
250115861
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| Publikation (Nr.) |
 copernicus.org/amt-7-2337-2014.pdf |
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| Zusammenfassung |
| We present lower/middle tropospheric column-averaged CH4
mole fraction time series measured by nine globally distributed
ground-based FTIR (Fourier transform infrared) remote sensing
experiments of the Network for the Detection of Atmospheric
Composition Change (NDACC). We show that these data are well
representative of the tropospheric regional-scale CH4
signal, largely independent of the local surface small-scale signals, and only weakly dependent on upper
tropospheric/lower stratospheric (UTLS) CH4 variations. In
order to achieve the weak dependency on the UTLS, we use an
a posteriori correction method. We estimate a typical precision for
daily mean values of about 0.5% and a systematic error of
about 2.5%. The theoretical assessments are complemented by
an extensive empirical study. For this purpose, we use surface
in situ CH4 measurements made within the Global Atmosphere
Watch (GAW) network and compare them to the remote sensing data. We
briefly discuss different filter methods for removing the local
small-scale signals from the surface in situ data sets in order to
obtain the in situ regional-scale signals. We find good agreement
between the filtered in situ and the remote sensing data. The
agreement is consistent for a variety of timescales that are
interesting for CH4 source/sink research: day-to-day,
monthly, and inter-annual. The comparison study confirms our
theoretical estimations and proves that the NDACC FTIR measurements
can provide valuable data for investigating the cycle of
CH4. |
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