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| Titel |
Carbon dioxide measurements in the nocturnal boundary layer over Amazonian forest |
| VerfasserIn |
A. D. Culf, G. Fisch, Y. Malhi, R. Carvalho Costa, A. D. Nobre, A. De O. Marques Filho, J. H. C. Gash, J. Grace |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 3, no. 1 ; Nr. 3, no. 1, S.39-53 |
| Datensatznummer |
250000754
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| Publikation (Nr.) |
 copernicus.org/hess-3-39-1999.pdf |
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| Zusammenfassung |
| Measurements of carbon dioxide concentration, temperature
and windspeed were made in the nocturnal boundary layer over a tropical forest near
Manaus, Brazil using a tethered balloon system. The measurements were made up to a maximum
height of 300 m on ten consecutive nights in November 1995. Simultaneous surface flux and
in-canopy concentration measurements were made at the surface close to the site. The
observation period included several different types of conditions. Generally strong
windshear and relatively weak temperature gradients prevented the formation of a strong
capping inversion to the nocturnal boundary layer. On some nights, however, the inversion
was sufficiently strong that the CO2 concentration at 100 m above the surface
exceeded 400 ppm. The concentration within the canopy was largely controlled by the
presence of an inversion very close to the canopy surface. The temperature and wind
profiles are contrasted with conditions in Randônia, Brazil, where the windshear was found
to be weaker and higher carbon dioxide concentrations were observed in the early morning.
The difference in carbon dioxide concentrations in the nocturnal boundary layer between
dusk and dawn is used to estimate the regional nighttime flux of carbon dioxide. The value
obtained generally exceeds the measured surface flux and sometimes exceeds the sum of the
surface flux and the in-canopy storage made at the tower site. The reasons for the
discrepancy are not clear; either one of the methods is in error or the regional carbon
dioxide budget differs significantly from the local budget measured at the tower site. |
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