# Stomatal and Non-Stomatal Turbulent Deposition Flux of Ozone to a Managed Peatland
## 2 Materials and Methods
### Data Analysis  
#### 2.3.1 Eddy Covariance  
The sensible heat flux (H), latent heat flux (LE), flux of CO\({}_{2}\) (\(F_{CO_{2}}\)) and \(F_{O_{3}}\) were calculated with the software EddyPro 6.2.0 (Licor Bioscience) [37] (see Equation (1), Section 2.3.2, for the calculation of the ozone flux). Raw data processing and flux calculation included de-spiking [38], double rotation of the 3D wind components, block averaging, lag correction with covariance maximization within defined bounds, corrections for sensor separation according to [PERSON] and Lenschow [39], high-frequency corrections according to [PERSON] et al. [40], and high-pass filtering effects according to [PERSON] et al. [41]. Additionally, the ozone fluxes were corrected for the dilution of the ozone concentration by water vapor, which was not measured within the instrument [42]. The calculated  
Figure 1: Photograph of the micrometeorological flux site in the Mittleres Wietingsmoor, NW Germany (left). Areal view (from Bing Maps) of the site with the overlaid daytime (light blue) and nighttime (purple) flux footprint during the experimental period (see Section 2.3 for more details) (right). Contour lines correspond to the 20%, 40%, 60% and 80% contributions to the flux footprints calculated according to [PERSON] et al. [36].  
fluxes were quality controlled for stationarity and integral turbulence characteristics [43]. The CO\({}_{2}\) storage term was estimated using the 1-point storage correction and then added to the CO\({}_{2}\) fluxes to derive the net ecosystem exchange (NEE). Noternal data were filtered for low friction velocity (u*) values. The u* threshold (0.1 m s\({}^{-1}\)) was estimated following [PERSON] et al. [44].  
Data quality control was performed according to [PERSON] and Foken [45] and resulted in three classes: QC_0 data are considered to be of very good quality, QC_1 data are of acceptable quality, and QC_2 data should not be considered for scientific data analysis. Further, data sets that are associated with low u* values (u* \(<\) 0.1 m s\({}^{-1}\)) are considered problematic because the respective turbulence is not sufficiently established. After removal of QC_2 data and those with low u* values (see Section 3.1 for details), the remaining data set was gap-filled with marginal distribution sampling as described in [PERSON] et al. [46]. Statistical analyses (Sections 3.2 and 3.3) were performed with non-gap-filled data.  
Subsequently, _NEE_ was partitioned into gross primary productivity (_GPP_) and ecosystem respiration (\(R_{eco}\)) by using daytime flux partitioning with light response curves [47] as implemented in REddyProc 1.0.0 for R [48].  
The flux footprints were calculated as described in [PERSON] et al. [36] for half-hour fluxes when the u* threshold was exceeded. Nighttime fluxes were calculated whenever the global radiation (i.e., the shortwave, downwelling radiation \(R_{g}\)) was below or equal to 5 W m\({}^{-2}\), while daytime conditions were defined for global radiation values above 200 W m\({}^{-2}\). With this classification, the transition periods around sunrise and sunset were excluded from the analysis.  
Co-spectra were computed for the vertical wind component in conjunction with temperature and O\({}_{3}\), respectively, for each half hour. Frequency-class binned averages were then used to calculate ensemble co-spectra from good-quality data and well-developed turbulence conditions for individual stability classes. Reference co-spectra for temperature and vertical wind were calculated according to [PERSON] and Finnigan [49].  
The stability of the boundary layer was determined from the ultrasonic anemometer data as (z-d)/L with L being the Monin-Obukhov length and d the displacement height (d = 0.67 \(\cdot\) z). Neutral stability conditions were defined as \(-0.03\leq\) z/L \(\leq\) 0.03, stable conditions as z/L \(>\) 0.03, and unstable conditions as z/L \(<\) \(-\)0.03, respectively.