Partitioning of ozone deposition over a developed maize crop between stomatal and non-stomatal uptakes, using eddy-covariance flux measurements and modelling

Ozone (O3) flux measurements, obtained by eddy-covariance technique, over a developed maize crop were used to partition the overall O3 deposition between stomatal and non-stomatal uptakes. Data were analysed using a big-leaf model, which was developed from current knowledge on O3 deposition. The classical parameters used in dry deposition models (i.e. the in-canopy aerodynamic resistance Rac, the intrinsic ground resistance Rig and the cuticular resistance Rcut) were determined for the maize crop from the relationship between the experimental non-stomatal conductance (gns) and the friction velocity (u*) in dry conditions (relative humidity (RH) < 60%). gns was determined as the difference between the O3 canopy conductance (gc) and the O3 stomatal conductance (gs), where gs was estimated by a method which combines the Penman–Monteith approach and the use of the CO2 assimilation flux.