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| Titel |
Measurement of advection of CO2 over grasslands in complex terrain in the Alps |
| VerfasserIn |
Peng Zhao, Albin Hammerle, Georg Wohlfahrt |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110970
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| Publikation (Nr.) |
 EGU/EGU2015-11029.pdf |
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| Zusammenfassung |
| The role of advection is often ignored in the estimation of net ecosystem exchange (NEE) of
CO2 in ecosystems. However, some studies reported that more realistic estimates of
night-time NEE could be gathered if horizontal and vertical advections are included. While
most of previous advection experiments have been conducted in forest ecosystems, grassland
ecosystems have a great advantage as measurements of advection can be realised with smaller
infrastructure and thus less experimental effort. In a preliminary simplified study, advection
showed an important contribution to NEE during night time at a sub-alpine grassland
site.
This three-year program is focused on the role of advection for NEE of grassland
ecosystems in complex terrain in the Alps. We are going to carry out field campaigns at four
sites which cover a range of terrain types typical for mountains with varying degrees of
complexity, including a valley-bottom site, a steep-slope site, a mixed-terrain site, and an
undulating-terrain site. Observations will take place in a notional control volume with a
length varying from 50 m to 5 m at each site in order to quantify the effects of horizontal
spatial scale on advection estimates. The observations at each site include vertical flux of
CO2 measured by eddy-covariance technique, horizontal and vertical advections of CO2
calculated from the measurement of wind components and CO2 gradients, and NEE
measured by chambers. Among all, the measurement of the horizontal advection of
CO2 needs many efforts because of small-scale variability in sources/sinks of CO2.
We are going to use tubes with multiple inlets, which allows sampling at multiple
positions across the faces at three heights of the control volume. Thus, we would be
able to quantify the contribution of advection to NEE at different grassland sites
situated in complex terrain in the Alps, and to quantify the effect of spatial scale of
advection measurements with a given experimental setup and accuracy on the inferred
fluxes and to devise the respective optimal spatial scales for advection experiments. |
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