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| Titel |
Role of advection for the ecosystem-atmosphere CO2 exchange of alpine grasslands |
| VerfasserIn |
Peng Zhao, Georg Wohlfahrt |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143949
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| Publikation (Nr.) |
 EGU/EGU2017-7721.pdf |
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| Zusammenfassung |
| The neglect of the advection contribution could bring uncertainties to the estimation of the
net ecosystem CO2 exchange (NEE) between ecosystems and the atmosphere, especially in
complex terrain and stable atmospheric conditions. In order to quantify the advection flux of
CO2, we carried out four monthly field campaigns at different grasslands in the mountainous
areas of Italy, Austria, and Germany in 2015 and 2016. The measurement was based on the
advection completed mass balance (ACMB) concept. A home-assembled solenoid valve
system, together with multiple sampling inlets and a gas analyser, was used to measure CO2
concentration online at three heights on the four sides of a control volume of 20 m
by 20 m. Advection of CO2 was then calculated from the measurement of wind
components and CO2 gradients. The turbulent flux of CO2 was measured by the
eddy-covariance technique. Three clear automatic chambers measured NEE as
reference.
Results showed that both the horizontal and vertical advection contributed more
significantly to CO2 flux at night time than at daytime. At most sites, the horizontal advection
played a more important role than the vertical advection. The above-canopy advection
contributed more CO2 flux than within-canopy advection due to the short canopy heights.
Large variability of NEE measured by the three chambers indicates the challenge of
comparing chamber and micrometeorological fluxes resulting from the heterogeneity of the
surface. |
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