Spatial analysis of footprint effects on CO2 flux measurements by eddy covariance method. A case study in rice paddy ecosystem
Résumé
The eddy covariance method is now widely used for estimating the net ecosystem CO2 flux (NEE) in various ecosystems. However, the spatial representativeness and scaling-up of such measurements are of the most critical issues. We investigated the effects of footprint on the CO2 flux measurements by the tower-sensor based on airborne/satellite remote sensing imagery. The spatial distribution of CO2 sink/source was derived from the spectral imagery and semi-empirical models. The flux value at the tower-sensor was estimated from the sink/source map combined with a footprint model. Comparison between estimated and measured flux values suggested that footprint effects cannot be negligible when the sink/source distribution is not uniform.