ECN publication
Determination of the relative importance of sources and sinks ofcarbon dioxide (NRP-proj. no. 852076)
Published by: Publication date:
ECN 1995
ECN report number: Document type:
ECN-C--95-035 ECN publication
Number of pages: Full text:
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The objective of the CO2 cluster of the Dutch National Research Programon Global Air Pollution and Climate Change, theme B (NOP MLK) was to formulate and validate CO2 exchange models that describe parts of the global carbon cycle. CO2 flux-measurements over grasslands were performed by ECN at two locations (Cabauw and Zegveld, the Netherlands). The data are used by Wageningen Agricultural University to tune and validate a CO2 exchange model for grasslands. This model should be able to simulate daily to seasonal variation of the exchange CO2 fluxes between the different parts of the grassland system and the exchange with the atmosphere. CO2 flux-measurements over a peat soil, using the eddy correlation technique started at Zegveld in March 1994 and ended in October 1994. The CO2 flux over a clay soil at Cabauw was determined from vertical CO2 concentration gradients. Measurements have been carried out since March 1993. CO2 concentration and carbon isotopic composition were measured at Cabauw at 200 m altitude. These measurements are meant for the verification and validation of CO2 exchange models on a sub-continental scale, and were analysed using different analyses tools. Preliminary model evaluation was performed using a GIS application. Using measured CO2 concentration and air mass trajectories over Europe, CO2 maps were calculated. These maps can be used to define areas of interest for further analysis. A transport model was developed to perform this analysis. The measured concentrations at 200 m and carbon isotope ratios were compared with the model results. Recently, a land use database with a grid of 10'x10' was provided by RIVM. Use of this database will improve the model performance due to the better description of spatial distribution of the sources (fossil fuel combustion) and source/sink systems (grassland/forest). So far, no model runs could be performed due to insufficient data on the spatial distribution of emissions. The model runs will be performed in 1995-1996. 37 figs., 6 tabs., 35 refs., 2 appendices

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