 |
| Titel |
Does inter-annual variability of Net Ecosystem Exchange exceed uncertainty? |
| VerfasserIn |
C. M. J. Jacobs, E. J. Moors, J. A. Elbers, W. W. P. Jans, B. Kruijt |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029216
|
|
|
|
|
|
| Zusammenfassung |
| The inter-annual variability of Net Ecosystem Exchange of CO2 (NEE) was studied using a
13-year record of eddy-covariance data from the Loobos forest flux site (Pinus Sylvestris) in
The Netherlands. The data were processed and quality-controlled following well-established
protocols. In addition, an angle-of-attack correction was performed to account for
contributions from wind directions outside the calibration range of the sonic anemometer as
well as a correction of the effect of surface heat exchange of the open-path gas analyzer on
the CO2 flux. Annual NEE varied by more than a factor of two between individual years.
Attempts were made to relate the observed NEE to several meteorological conditions,
hydrological conditions, ecosystem response characteristics, and nitrogen and ozone
deposition, with and without consideration of time lags. Overall, none of these factors or
factor combinations consistently explained the year-to-year variations. In some cases
differences between individual years could be explained by considering sub-seasonal
variations, such as differences in ecosystem respiration caused by excessive drought
followed by excessive precipitation in one year but not in the other or temporary
reduction of carbon uptake due to storm damage. The question arises whether or not the
inter-annual variability exceeds uncertainty because of uncertainty in the eddy covariance
measurements and its corrections and uncertainty in ecosystem characteristics. For the
Loobos site some major uncertainties will also be highlighted and compared with the
inter-annual variability. Implications for modeling approaches will be discussed. |
|
|
|
|
|
|