Table 2.

CO₂ fluxes and their uncertainties with different processing procedures

FC (unit: μmol m−2 s−1)	Mean	Std.	25%	50%	75%
Default (double rotation & block averaging only)	8.8	7.3	2.3	7.8	14.4

Difference with default (EXP-default; unit: μmol m−2 s−1)
Coordinate rotation
Triple rotation	− 0.1	1.5	0.0	0.0	0.1
Planar fit [24]	− 0.8	3.8	− 1.7	− 0.5	0.3
Planar fit [25]	− 1.0	3.9	− 1.9	− 0.6	0.3
Detrending
Linear detrending	− 0.4	3.9	− 1.3	− 0.1	0.4
Running mean 250 s	− 0.7	4.3	− 2.0	− 0.5	0.8
Exponential running mean 250 s	− 0.9	3.8	− 2.0	− 0.6	0.2
Time Lags Compensation
Covariance maximization	0.0	0.1	0.0	0.0	0.1
Covariance maximization with default	0.1	0.1	0.0	0.0	0.1
Automatic time lag Optimization	0.0	0.1	0.0	0.0	0.1
Spike count/removal
Mauder et al. [26], accepted spikes 1–30%	− 0.5	1.4	− 0.3	0.0	0.0
Vickers and Mahrt [27] (VM97), Max consecutive outliers (MCO) 3	− 0.1	0.2	− 0.1	0.0	0.0
VM97, MCO 10	− 0.2	0.4	− 0.2	0.0	0.0
VM97, MCO 30	− 0.3	0.7	− 0.4	− 0.1	0.0
VM97, MCO 50	− 0.4	0.8	− 0.4	− 0.1	0.0
VM97, MCO 70	− 0.4	0.8	− 0.5	− 0.1	0.0
Amplitude resolution
4–7 sigma, number of bins 50–150	0.0	0.1	0.0	0.0	0.1
Dropouts
Accepted central dropouts 5–20%	0.0	0.1	0.0	0.0	0.1
Absolute limits	0.0	0.1	0.0	0.0	0.1
Skewness & Kurtosis	0.0	0.1	0.0	0.0	0.1
Discontinuities	0.0	0.1	0.0	0.0	0.1
Spectral correction
Low-frequency range [28]	0.3	0.4	0.1	0.2	0.4
High-frequency range (HFR) [29]	0.1	0.2	0.0	0.1	0.2
HFR [30, 31]	0.7	1.0	0.2	0.4	0.8
HFR [32]	0.2	0.3	0.0	0.1	0.4
HFR [33] with Horst and Lenschow [34] (HL09): along-wind, cross, and vertical winds	0.1	0.2	0.0	0.1	0.2
HFR [33] with HL09: only cross and vertical winds	0.1	0.1	0.0	0.1	0.2
HFR [35] with HL09: along-wind, cross, and vertical winds	0.2	0.2	0.0	0.1	0.3
HFR [35] with HL09: only cross and vertical winds	0.2	0.2	0.0	0.1	0.3

Data period is 1-month (March 2015) from HU site. Italic indicates the methods applied in this study