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| Titel |
Comparison between eddy covariance and automatic chamber techniques for measuring net ecosystem exchange of carbon dioxide in cotton and wheat fields |
| VerfasserIn |
K. Wang, C. Liu, X. Zheng, M. Pihlatie, B. Li, S. Haapanala, T. Vesala, H. Liu, Y. Wang, G. Liu, F. Hu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-02), S.6865-6877 |
| Datensatznummer |
250085388
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| Publikation (Nr.) |
 copernicus.org/bg-10-6865-2013.pdf |
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| Zusammenfassung |
| Static and transparent automatic chamber (AC) technique is a necessary choice
for measuring net ecosystem exchange (NEE) of carbon dioxide (CO2) in
circumstances where eddy covariance (EC) technique is not applicable.
However, a comparison of the two techniques for measurements on croplands has
seldom been undertaken. We carried out NEE observations in a cotton field
(for one year) and a winter wheat field (for one cropping season) using both
AC and EC techniques, to (a) compare the NEE fluxes measured using each
technique, and (b) test the NEE measurement performance of an automatic
chamber system (AMEG), which was designed for simultaneous flux measurements
of multiple gases. The half-hourly NEE fluxes measured with the two
techniques were in approximate agreement, with the AC fluxes being 0.78
(cotton) and 1.06 (wheat) times the size of the EC fluxes. When integrated to
daily timescale, the fluxes of the two techniques were in better agreement,
showing an average ratio of 0.94 and 1.00 for the cotton and wheat,
respectively. During the periods with comparable field conditions and normal
performance of both instruments, the cumulative NEE fluxes revealed small
differences between the two techniques (−9.0% ~ 7%, with a
mean of 0.1%). The measurements resulted in an annual cumulative NEE of
−40 g C m−2 yr−1 (EC) and −42 g C m−2 yr−1
(AC) in the cotton field, and a seasonal cumulative NEE of
−251 g C m−2 (EC) and −205 g C m−2 (AC) in the wheat
field. Our results indicate that, for cropland populated by short plants, the
AMEG system and the data processing procedures applied in this study are able
to provide NEE estimates comparable to those from EC measurements. |
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