Influences of various calculation options on heat, water and carbon fluxes determined by open- and closed-path eddy covariance methods

Masahito Ueyama; Ryuichi Hirata; Masayoshi Mano; Ken Hamotani; Yoshinobu Harazono; Takashi Hirano; Akira Miyata; Kentaro Takagi; Yoshiyuki Takahashi

doi:10.3402/tellusb.v64i0.19048

Influences of various calculation options on heat, water and carbon fluxes determined by open- and closed-path eddy covariance methods

Tellus B: Chemical and Physical Meteorology

Volume 64 (2012): Issue 1

By: Masahito Ueyama, Ryuichi Hirata, Masayoshi Mano, Ken Hamotani, Yoshinobu Harazono, Takashi Hirano, Akira Miyata, Kentaro Takagi and Yoshiyuki Takahashi

Open Access

|Jan 2012

Figures & Tables

Locations and vegetation types of the study sites.

Table 1. Annual values of fluxes and the u*-threshold of the control calculation. The differences between the open- and closed-path systems are also shown

Site Climate Vegetation Location Year Canopy height (m) T_annual (°C) BRW Arctic Wet sedge tundra 71°19′13′′N, 156°37′20′′W 2003 0.1 −11.5 UAF Boreal Black spruce forest 64°52′N, 147°51′W 2007 1.5 −3.5 TSE Temperate Larch and Sasa forest 45°03′N, 142°06′E 2010 1.5 (Sasa)–3 (larch) 6.5 TMK Temperate Larch forest 42°44′N, 141°31′E 2003 15 6.6 MSE Temperate Rice paddy 36°3′N, 140°01′E 2005 0.05–1.2 13.3 FHK Temperate Larch forest 35°26′38′′N, 138°45′53′′E 2006 17 9.6 PDF Tropical Peat swamp forest 2°20′42′′S, 114°2′11′′E 2003–2004 26 26.1 Site Measurement height (m) Sampling (Hz) Sonic anemometer model IRGA model Sonic span (m) Sensor separation (m) BRW 1.9 10 DA600-TR62AX^a LI7500^c 0.1 0.15 UAF 6 10 CSAT3^b LI7500^c 0.1 0.30 TSE 5.6 10 DA600-3TV^a LI7500^c/LI7000^c 0.2 0.38 TMK 27 10 DA600-3TV^a LI7500^c/LI6262^c 0.2 0.49 MSE 3.0–3.3 10 DA600-TR62AX^a LI7500^c/LI7000^c 0.1 0.25 FHK 35 10 DA600-3TV^a LI7500^c/LI6262^c 0.2 0.30 PDF 41 10 CSAT3^b LI7500^c 0.1 0.20

[i] ^aKaijo, Japan.

[ii] ^bCampbell Scientific Inc., USA.

[iii] ^cLi-Cor, USA.

[iv] Note: T_annual is mean annual air temperature.

Schematic of the processing of half-hourly and annual fluxes as well as related parameters for non-linear regressions. In this study, all of the processing steps except flux calculation were conducted in the same manner. The details of the flux calculations are shown in Fig. 3.

Table 2. In the control experiment, the flux calculation was performed by applying all preferable corrections: the despiking, the crosswind and water vapor corrections to the sensible heat flux, the double rotation, the high-frequency loss correction, the prescribed lag-time correction between open-path sensor and sonic anemometer, a lag-time correction for the closed-path systems and the WPL correction

Experiment Despiking Detrending Rotation Crosswind^a Water vapor Lag-time open Lag-time closed High-frequency loss Mammarella WPL SelfHeat^b Storage Control ○ ○ ○ ○ ○ ○ ○ ○ NoDR ○ ○ ○ ○ ○ ○ ○ PFR^c ○ ○ ○ ○ ○ ○ ○ ○ DRext^d ○ ○ ○ ○ ○ ○ ○ ○ TR^e ○ ○ ○ ○ ○ ○ ○ ○ NoWV ○ ○ ○ ○ ○ ○ ○ NoCW ○ ○ ○ ○ ○ ○ ○ NoDespike ○ ○ ○ ○ ○ ○ ○ Detrend1^f ○ ○ ○ ○ ○ ○ ○ ○ ○ Detrend2^g ○ ○ ○ ○ ○ ○ ○ ○ ○ NoHL ○ ○ ○ ○ ○ ○ ○ SelfHeat ○ ○ ○ ○ ○ ○ ○ ○ ○ Mammarella ○ ○ ○ ○ ○ ○ ○ ○ Storage ○ ○ ○ ○ ○ ○ ○ ○ ○

[i] ^aA no crosswind correction experiment (NoCW) was conducted only for sites where CSAT3 was not used because CSAT3 automatically corrected the effect of crosswind to the virtual air temperature.

[ii] ^bThe self-heating correction was only for the open-path eddy covariance systems.

[iii] ^cIn PFR experiment, a planar fit rotation is applied.

[iv] ^dIn DRext experiment, an extended double rotation is applied.

[v] ^eIn TR experiment, a triple rotation is applied.

[vi] ^fIn Detrend1 experiment, a first-order detrending is applied.

[vii] ^gIn Detrend2 experiment, a second-order detrending is applied.

Flowchart of the flux calculation. Theoretical high-frequency loss corrections are applied to momentum, heat and CO₂/H₂O fluxes by open-path systems, whereas empirical ones are for CO₂/H₂O fluxes by closed-path systems. The dashed line represents the flow of the control calculation. In the control calculation, double rotation is applied for the coordinate rotation, and the empirical high-frequency loss correction by Aubinet et al. (2000) is applied to closed-path systems.

Table 3. Annual values of fluxes and the u*-threshold of the control calculation. The differences between the open- and closed-path systems are also shown

Site System H (W m⁻²) ET (mm yr⁻¹) Difference ET^a (mm yr⁻¹) NEE (g C m⁻² yr⁻¹) Difference NEE^a (g C m⁻² yr⁻¹) GPP (g C m⁻² yr⁻¹) Difference GPP^a (g C m⁻² yr⁻¹) RE (g C m⁻² yr⁻¹) Difference RE^a (g C m⁻² yr⁻¹) u*-threshold (m s⁻¹) BRW Open 5.1 132 −169 252 83 0.23 UAF Open 11.3 239 6 721 727 0.18 TSE Open −2.2 409 124 −322 −407 1429 25 1107 −382 0.25 Closed 285 85 1404 1488 0.28 TMK Open 24.9 637 163 −657 −453 1993 −99 1337 −552 0.34 Closed 474 −204 2092 1888 0.35 FHK Open 33.7 504 29 −895 −591 2113 225 1218 −366 0.33 Closed 475 −304 1888 1584 0.30 MSE Open −0.5 956 178 −246 −203 1170 −22 924 −225 0.20 Closed^b 382 −166 1124 958 0.19 PDF Open 20.3 1282 53 3198 3251 0.24

[i] ^aThe difference is calculated as flux by the closed-path system subtracted from the open-path system.

[ii] ^bThe closed path system in the MSE site were only operated in the growing season between DOY 105 and 294.

[iii] The difference between the open- and closed-path systems were calculated for this period.

Slope and intercept determined by regression of the half-hourly fluxes between the control and comparative calculations for the open-path systems. The following corrections were applied: no double rotation (NoDR), planar fit rotation (PFR), extended DR (DRext), triple rotation (TR), no water vapor correction (NoWV), no crosswind correction (NoCW), no despiking (NoDespike), first-order detrending (Detrend1), second-order detrending (Detrend2), no high-frequency loss correction (NoHL) and self-heating correction (SelfHeat).

Slope and intercept determined by regression of the half-hourly fluxes between the control and comparative calculations for the closed-path systems. In the closed-path calculation, the relative humidity effect for the high-frequency loss correction (Mammarella correction) was examined.

Table 4. Slope values of linear regression between control and other experiments at a half-hourly basis. Slopes greater than 1 represent that fluxes from comparative experiments had greater magnitude than those from the control experiment

Flux Site System NoDR PFR DRext TR NoWV NoCW NoDespike Detrend1 Detrend2 NoHL SelfHeat Mammarella H BRW 0.96 0.93 0.98 0.95 1.02 1.01 1.00 0.99 0.99 0.99 – – UAF 1.03 1.03 0.99 0.95 1.02 – 1.00 0.99 0.97 0.98 – – TSE 0.98 0.98 0.99 0.91 1.03 1.01 1.00 0.98 0.98 0.98 – – TMK 1.00 1.00 1.00 0.87 1.03 1.04 1.00 0.98 0.97 0.98 – – FHK 0.95 0.96 0.99 0.85 1.01 1.02 1.00 0.97 0.95 0.97 – – MSE 0.95 0.97 1.01 0.95 1.05 1.01 1.00 0.99 0.98 0.99 – – PDF 0.97 0.97 0.98 0.90 1.10 – 1.00 0.94 0.91 0.95 – – Average^a 0.98^ns 0.98^ns 0.99^ns 0.99* 1.04** 1.02** 1.00** 0.98** 0.96* 0.98* – – LE BRW Open 0.96 0.94 1.00 0.96 1.00 1.00 1.00 0.99 0.99 0.95 – – UAF Open 1.02 1.03 0.99 0.96 1.00 – 1.00 0.98 0.96 0.94 – – TSE Open 0.97 0.98 0.98 0.93 1.00 1.00 1.00 0.98 0.96 0.94 – – Closed 0.95 0.97 0.98 0.92 0.99 1.00 1.00 0.97 0.96 0.76 – 1.00 TMK Open 1.01 1.01 1.00 0.85 1.00 1.00 1.00 0.98 0.96 0.96 – – Closed 1.01 1.01 1.00 0.84 1.00 1.00 1.00 0.97 0.95 0.74 – 1.13 FHK Open 0.95 0.95 0.99 0.85 1.00 1.00 1.00 0.96 0.92 0.95 – – Closed 0.94 0.94 0.99 0.83 1.00 1.00 1.00 0.95 0.92 0.78 – 0.95 MSE Open 0.93 0.97 1.00 0.95 1.00 1.00 1.00 0.99 0.99 0.94 – – Closed 0.91 0.97 1.00 0.95 0.99 1.00 1.00 0.99 0.98 0.66 – 0.87 PDF Open 0.96 0.97 0.98 0.91 1.01 – 1.00 0.95 0.91 0.94 – – Average^a Open 0.97^ns 0.98^ns 0.99** 0.92* 1.00* 0.83* 1.00* 0.98* 0.96* 0.95* – – Closed 0.95^ns 0.97^ns 0.99^ns 0.89* 0.99* 1.00^ns 1.00* 0.97* 0.95* 0.74* – 0.99^ns Both 0.97** 0.98^ns 0.99** 0.91* 1.00^ns 1.00^ns 1.00* 0.97* 0.95* 0.87* – 0.99^ns Fc BRW Open 0.94 0.92 0.99 0.94 0.98 0.96 1.00 0.97 0.96 0.91 – – UAF Open 1.01 0.97 0.97 0.93 0.98 – 1.00 0.93 0.90 0.86 0.99 – TSE Open 0.98 0.98 0.99 0.88 0.98 1.00 1.00 0.98 0.97 0.91 0.96 – Closed 0.97 0.98 1.00 0.89 1.00 1.00 1.01 0.98 0.97 0.78 – 1.00 TMK Open 0.99 0.99 1.00 0.83 0.98 0.99 1.00 0.97 0.96 0.95 0.98 – Closed 1.00 1.00 1.00 0.84 0.99 1.00 1.00 0.98 0.96 0.89 – 1.00 FHK Open 0.95 0.95 0.99 0.82 0.99 1.00 1.00 0.96 0.93 0.94 0.97 – Closed 0.89 0.95 0.99 0.81 1.00 1.00 1.00 0.96 0.93 0.92 – 0.94 MSE Open 0.93 0.98 1.00 0.95 0.98 1.00 1.00 0.98 0.97 0.92 0.99 – Closed 0.93 0.99 1.01 0.97 0.99 1.00 1.00 0.99 0.98 0.87 – 1.00 PDF Open 0.96 0.97 0.99 0.92 0.97 – 1.00 0.95 0.92 0.95 1.03 – Average^a Open 0.97** 0.97* 0.99^ns 0.90* 0.98* 0.99^ns 1.00* 0.96* 0.94* 0.92* 0.99^ns – Closed 0.95^ns 0.98^ns 1.00^ns 0.88* 1.00** 1.00^ns 1.00^ns 0.98* 0.96* 0.87* – 0.99^ns Both 0.96* 0.97* 0.99^ns 0.89* 0.98* 0.99^ns 1.00** 0.97* 0.95* 0.90* 0.99^ns 0.99^ns

[i] ^aSuperscripts of “ns”, “*”, and “**” represent that averaged slope was statistically no significant from 1.0 (p>0.10), significant (p<0.05), and significant (0.05<p<0.10), respectively.

Table 5. Intercept values of linear regression between control and other experiments at a half-hourly basis. Positive values represent that fluxes from comparative experiments were larger than those from the control experiment

Flux Site System NoDR PFR DRext TR NoWV NoCW NoDespike Detrend1 Detrend2 NoHL SelfHeat Mammarella H (W m⁻²) BRW 0.81 0.58 0.58 0.96 0.31 2.91 −0.01 −0.04 −0.07 0.03 – – UAF 0.21 1.08 0.10 1.65 0.70 – −0.08 −0.11 −0.20 −0.07 – – TSE −0.09 −0.25 −0.25 2.47 1.40 1.20 −0.07 0.02 0.00 −0.12 – – TMK −0.61 −0.62 0.05 0.92 1.64 4.27 −0.04 0.08 −0.06 −0.34 – – FHK −1.29 −0.43 0.42 2.97 1.76 3.28 −0.03 −0.26 −0.57 −1.04 – – MSE 0.70 0.28 −0.17 0.57 4.08 1.10 −0.01 0.09 0.10 −0.01 – – PDF 0.75 0.11 0.14 0.59 3.63 – −0.18 0.27 0.06 −0.41 – – Average 0.07^ns 0.11^ns 0.12^ns 1.45** 1.93** 2.55** −0.06^ns 0.01^ns −0.11^ns −0.28^ns – – LE (W m⁻²) BRW Open −0.11 −0.13 0.00 0.17 0.00 0.05 0.01 0.05 0.05 0.00 – – UAF Open 0.58 0.73 0.42 0.16 −0.01 – 0.00 0.34 0.49 0.04 – – TSE Open 0.54 0.37 0.45 −0.54 −0.02 0.05 0.04 0.43 0.61 −0.14 – – Closed 0.27 0.22 0.33 −0.29 0.02 −0.04 0.01 0.35 0.40 −0.48 – 1.87 TMK Open 0.10 0.09 0.01 0.86 −0.05 0.09 0.11 0.29 0.29 −0.18 – – Closed 0.05 0.08 0.03 0.24 0.03 −0.02 0.01 0.34 0.19 0.40 – 2.54 FHK Open 0.35 0.35 0.17 0.37 −0.02 0.06 0.07 0.72 1.25 −0.04 – – Closed −0.43 0.51 0.55 1.30 0.02 0.06 0.02 0.86 1.23 0.64 – 2.39 MSE Open 0.30 0.06 0.36 0.89 −0.03 0.01 0.01 0.07 0.05 −0.57 – – Closed −1.56 −1.23 −0.39 0.94 0.01 −0.01 −0.01 0.19 −0.07 0.93 – 7.62 PDF Open 1.53 1.50 1.29 1.93 0.04 – 0.03 1.79 2.99 0.25 – – Average^a Open 0.47^ns 0.42^ns 0.39^ns 0.55^ns −0.02^ns 0.05* 0.04** 0.53^ns 0.82^ns −0.09^ns – – Closed −0.42^ns −0.11^ns −0.13^ns 0.55^ns 0.02* 0.00^ns 0.01^ns 0.43** 0.44^ns 0.37^ns – 3.61** Both 0.15^ns 0.23^ns 0.29^ns 0.55^ns 0.00^ns 0.03^ns 0.03^ns 0.49^ns 0.68^ns 0.08^ns – 3.61** Fc (µmol m⁻² s⁻¹) BRW Open 0.00 0.00 −0.02 −0.06 0.02 0.10 0.00 −0.02 −0.02 0.00 0.05 – UAF Open −0.05 −0.16 −0.04 −0.12 0.07 – 0.01 −0.04 −0.06 −0.07 0.79 – TSE Open 0.03 0.02 0.04 0.02 0.07 0.06 0.02 −0.02 −0.03 −0.12 0.36 – Closed 0.03 0.04 0.00 −0.19 −0.04 −0.05 −0.03 −0.05 −0.05 −0.27 – −0.04 TMK Open 0.05 0.05 0.00 0.02 0.07 0.27 0.04 −0.04 −0.03 −0.03 0.46 – Closed 0.01 0.02 0.00 0.06 0.00 −0.01 0.04 0.00 0.00 −0.20 – 0.00 FHK Open 0.05 −0.02 −0.03 0.01 0.04 0.20 0.01 −0.08 −0.11 −0.01 0.33 – Closed 0.19 −0.01 −0.02 0.04 0.00 0.00 0.01 −0.04 −0.03 −0.10 – 0.25 MSE Open −0.10 −0.05 0.02 −0.02 0.21 0.06 0.00 −0.01 −0.01 −0.07 0.56 – Closed −0.14 −0.06 0.00 0.03 0.00 0.00 0.01 0.02 0.01 −0.19 – −0.05 PDF Open −0.16 −0.04 −0.01 0.11 0.28 – 0.02 0.05 0.10 0.11 0.09 – Average^a Open −0.03^ns −0.03^ns −0.01^ns 0.00^ns 0.11** 0.14* 0.01** −0.02^ns −0.02^ns −0.03^ns 0.38* – Closed −0.02^ns −0.01^ns 0.00^ns −0.02^ns −0.01^ns −0.02^ns 0.01^ns −0.02^ns −0.02^ns −0.19* – 0.04^ns Both −0.01^ns −0.02^ns −0.01^ns −0.01^ns 0.07^ns 0.07^ns 0.01^ns −0.02^ns −0.02^ns −0.09^ns 0.38* 0.04^ns

[i] ^aSuperscripts of “ns”, “*”, and “**” represent that averaged intercept was statistically no significant from 0.0 (p>0.10), significant (p<0.05), and significant (0.05<p<0.10), respectively.

Table 6. Slope, intercept and R ² values of linear regression between fluxes by open- and closed-path systems at the control experiment

LE control (W m⁻²) LE Mammarella (W m⁻²) Fc control (µmol m⁻² s⁻¹) Site Slope Intercept R² Slope Intercept R² Slope Intercept R² FHK 1.05 3.33 0.93 1.01 4.13 0.9501 1.05 1.31 0.94 MSE 1.01 −19.51 0.95 0.91 −10.76 0.93 1.01 0.78 0.99 TMK 0.99 −4.51 0.92 1.12 3.44 0.93 1.02 0.84 0.96 TSE 0.93 −4.68 0.95 0.92 −2.14 0.96 0.94 1.01 0.97 Average 0.99 −6.34 0.94 0.99 −1.33 0.94 1.00 0.98 0.97 Interval 0.06 11.22 0.02 0.11 8.10 0.02 0.06 0.28 0.02

Differences between the control and comparative calculations of the annual value of the sensible heat flux (H) and NEE as well as the ratios of the comparative to control calculations for the annual values of evapotranspiration (ET), gross primary productivity (GPP) and ecosystem respiration (RE). The positive bias in NEE means decrease in the sink or increase in the source.

Table 7. Differences between the control and comparative calculations of the annual value of the sensible heat flux (H) and NEE as well as the ratios of the comparative to control calculations for the annual values of evapotranspiration (ET), gross primary productivity (GPP) and ecosystem respiration (RE). The positive bias in NEE means decrease in the sink or increase in the source

Flux Site System NoDR PFR DRext TR NoWV NoCW NoDespike Detrend1 Detrend2 NoHL Mammarella Storage SelfHeat H (W m⁻²) BRW 0.3 0.0 0.4 1.4 0.3 3.8 0.0 0.2 0.2 −0.1 – – – UAF 2.1 −0.2 −0.6 1.6 1.0 – −0.2 0.7 0.8 −0.6 – – – TSE 0.5 −0.9 1.0 4.0 1.8 2.5 −0.5 −0.4 −0.3 0.2 – – – TMK −1.0 −0.9 −0.1 −2.6 0.9 9.0 0.2 −0.3 −1.0 −1.0 – – – FHK 1.0 −7.3 −1.4 −2.5 2.8 1.1 0.2 −1.1 −1.9 −3.2 – – – MSE 0.8 −0.5 −0.8 0.5 4.2 1.0 0.4 0.8 0.5 −0.2 – – – PDF −0.3 −1.2 −1.0 −2.4 5.8 – −1.2 −0.5 −1.9 −1.8 – – – Average^a 0.5^ns −1.6^ns −0.4^ns 0.0^ns 2.4** 3.5^ns −0.2^ns −0.1^ns −0.5^ns −0.9^ns – – – Interval^b 1.9 5.0 1.7 5.0 3.9 7.0 1.1 1.3 2.1 2.3 – – – ET (%) BRW Open −5.8 −6.6 −0.2 −3.0 0.0 1.1 −1.1 −1.3 −2.2 −4.9 – – – UAF Open 0.0 5.4 0.4 −5.5 0.7 – −0.2 −6.4 −8.7 −4.9 – – – TSE Open −7.6 1.1 −3.0 −8.9 3.5 6.8 4.4 3.4 0.9 −5.2 – – – Closed −5.2 −3.5 −8.2 −10.5 −0.8 −0.6 1.1 −1.5 −4.2 −30.9 21.9 – – TMK Open 1.8 1.8 0.0 −14.4 −1.6 1.6 −0.8 −4.6 −5.5 −4.0 – – – Closed 2.2 2.1 1.3 −16.0 −1.7 −0.9 0.0 −3.7 −6.6 −26.5 23.6 – – FHK Open −0.6 −6.8 −0.2 −20.1 2.1 1.2 0.1 −0.7 −4.7 −3.5 – – – Closed 2.9 −6.1 0.6 −20.9 −4.5 −1.2 −0.3 −4.6 −8.0 −24.1 −0.2 – – MSE Open −7.2 −1.6 −0.1 −5.8 0.8 0.8 0.1 −3.0 −2.9 −6.2 – – – Closed −13.1 −4.7 −1.5 −5.4 −0.6 0.1 0.7 −1.6 −2.9 −32.5 −1.0 – – PDF Open −2.7 −3.1 −1.6 −9.2 −0.1 – 2.2 −4.2 −7.7 −5.6 – – – Average^a Open −3.1^ns −1.4^ns −0.7^ns −9.5* 0.8^ns 2.3^ns 0.7^ns −2.4^ns −4.4* −4.9* – – – Closed −3.3^ns −3.0^ns −1.9^ns −13.2* −1.9^ns −0.6^ns 0.4^ns −2.8* −5.4* −28.5* 11.1^ns – – Both −3.2^ns −2.0^ns −1.2^ns −10.9* −0.2^ns 1.0^ns 0.6^ns −2.6** −4.8* −13.5** 11.1^ns – – Interval^b Open 7.3 8.8 2.3 11.5 3.2 5.4 3.8 6.3 6.4 1.8 – – – Closed 17.6 8.5 10.1 15.7 4.3 1.3 1.5 3.6 5.5 9.1 31.8 – – Both 9.1 7.4 4.7 11.1 3.8 4.4 2.8 4.8 5.3 22.0 31.8 – – NEE (g C m⁻² yr⁻¹) BRW Open 11.7 16.8 −3.8 5.4 6.8 35.4 5.7 4.5 7.1 13.2 – −5.8 20.6 UAF Open 12.8 −82.0 −39.8 −31.8 10.6 – 7.9 41.1 37.2 −23.7 – −112.4 305.9 TSE Open 80.5 59.3 96.0 93.3 91.6 80.8 54.0 41.7 54.5 4.9 – −16.7 146.5 Closed 6.7 17.1 7.7 −71.4 −0.4 −5.6 1.5 −98.9 −109.2 −87.1 – −125.2 – TMK Open 19.5 17.2 −5.5 161.1 24.1 129.9 26.3 −22.4 −9.5 30.9 – 1.0 161.3 Closed 3.5 10.5 5.8 61.4 −25.7 −9.6 14.1 −53.0 −71.3 −59.4 – −19.6 – FHK Open 86.1 −41.2 2.5 224.8 47.7 11.2 13.7 18.4 51.6 25.4 – −8.1 134.6 Closed −19.0 −6.9 19.8 87.1 −102.0 9.0 1.7 −12.2 36.2 7.9 – 4.1 – MSE Open −27.1 −42.8 −7.7 2.3 67.9 22.5 7.1 23.4 26.4 13.0 – −14.5 180.1 Closed −34.1 −30.8 −9.0 10.7 2.0 −2.0 0.4 4.6 5.8 −23.6 – −23.1 – PDF Open −52.7 −3.2 −3.0 126.3 168.0 – −206.0 145.7 200.1 62.4 – −41.3 51.9 Average^a Open 18.7^ns −10.8^ns 5.5^ns 83.1^ns 59.5** 55.9** −13.1^ns 36.1^ns 52.5^ns 18.0^ns – −28.2^ns 143.0* Closed −10.8^ns −2.5^ns 6.1^ns 21.9^ns −31.5^ns −2.0^ns 4.4^ns −39.9^ns −34.6^ns −40.5^ns – −40.9^ns – Both 8.0^ns −7.8^ns 5.7^ns 60.8^ns 24.6^ns 30.2^ns −6.7^ns 8.5^ns 20.8^ns −3.3^ns – −32.9^ns 143.0* Interval^b Open 99.2 92.3 82.1 184.2 110.6 104.6 168.6 103.3 134.2 51.1 – 76.6 180.2 Closed 45.5 50.4 27.8 164.4 114.4 18.8 15.2 108.7 158.2 97.6 – 135.3 – Both 78.9 70.4 60.5 160.1 125.1 86.4 123.0 111.8 142.1 77.0 – 80.4 180.2 GPP (%) BRW Open −14.8 −18.6 −9.8 −14.4 −3.8 −2.3 −4.4 −11.6 −7.3 −15.9 – 0.3 −10.6 UAF Open 8.7 −3.6 −4.4 1.7 −2.3 – −0.4 0.5 −3.0 −13.3 – −6.4 5.7 TSE Open −6.4 −6.8 −5.7 −16.9 −6.4 −3.2 −3.5 −4.2 −4.8 −7.3 – 2.7 −10.7 Closed −6.2 −4.2 −2.9 −18.2 −2.6 −2.2 −0.5 3.2 3.7 −29.2 – 7.3 – TMK Open 0.4 0.3 0.3 −9.0 −2.6 3.3 0.6 −3.3 −4.7 −4.8 – 3.1 −3.1 Closed 0.4 1.0 2.4 −9.9 −0.5 −0.9 −0.7 −1.0 −5.4 −13.2 – 0.6 – FHK Open 11.5 6.7 1.2 −10.1 1.8 9.6 0.0 −1.8 −0.2 −11.7 – 6.7 −4.8 Closed 2.8 −3.9 2.9 −12.5 3.7 −0.8 0.7 0.6 1.3 −12.1 – 7.2 – MSE Open −9.9 −4.0 0.8 −5.7 −2.3 2.1 0.2 −2.8 −4.4 −8.7 – 2.0 −2.6 Closed −10.1 −4.6 −0.7 −4.5 −0.8 −0.6 0.3 −1.6 −2.2 −20.2 – 1.1 – PDF Open −4.6 −2.9 −2.0 −7.2 −2.9 – −2.1 −3.0 −4.1 −4.1 – 22.7 2.4 Average^a Open −2.2^ns −4.1^ns −2.8^ns −8.8* −2.7* 1.9^ns −1.4^ns −3.7* −4.1* −9.4* – 4.4^ns −3.4^ns Closed −3.3^ns −2.9^ns 0.4^ns −11.3* −0.1^ns −1.1* −0.1^ns 0.3^ns −0.6^ns −18.7* – 4.1^ns – Both −2.6^ns −3.7^ns −1.6^ns −9.7* −1.7^ns 0.5^ns −0.9^ns −2.3^ns −2.8^ns −12.8* – 4.3^ns −3.4^ns Interval^b Open 18.6 14.9 7.9 11.8 4.7 10.9 3.9 7.4 4.1 8.6 – 17.5 11.8 Closed 14.0 6.2 6.3 13.4 6.3 1.7 1.6 5.0 9.3 18.6 – 8.7 – Both 14.7 11.2 7.0 10.5 4.9 7.4 3.1 6.8 5.9 13.1 – 13.2 11.8 RE (%) BRW Open −30.9 −36.2 −34.5 −37.4 −3.3 35.6 −6.5 −30.0 −13.6 −32.4 – −6.2 −7.3 UAF Open 10.4 −14.9 −9.9 −2.7 −0.9 – 0.7 6.2 2.1 −16.5 – −21.8 47.7 TSE Open −1.0 −3.5 1.2 −13.4 0.0 3.1 0.3 −1.7 −1.3 −9.1 – 2.0 −0.5 Closed −5.4 −2.8 −2.2 −22.0 −2.5 −2.5 −0.4 −3.7 −3.9 −33.4 – −1.5 – TMK Open 2.1 1.7 0.1 −1.3 −2.1 14.6 2.9 −6.7 −7.7 −4.8 – 3.9 7.5 Closed 0.6 1.7 2.9 −7.7 −2.0 −1.5 0.0 −3.9 −9.7 −17.8 – −0.3 – FHK Open 27.0 8.2 2.3 1.0 7.0 17.5 1.2 −1.5 3.8 −18.2 – 11.0 2.8 Closed 2.2 −5.1 4.7 −9.4 −2.1 −0.4 1.0 −0.1 3.9 −13.9 – 8.8 – MSE Open −15.4 −9.7 0.2 −7.0 4.4 5.0 1.1 −1.0 −2.8 −9.6 – 0.9 16.2 Closed −15.4 −8.6 −1.8 −4.1 −0.7 −1.0 0.3 −1.4 −1.9 −26.2 – −1.1 – PDF Open −6.1 −2.9 −2.1 −3.2 2.3 – −8.4 1.5 2.1 −2.1 – 21.1 4.0 Average^a Open −2.0^ns −8.2^ns −6.1^ns −9.1^ns 1.1^ns 15.2* −1.2^ns −4.7^ns −2.5^ns −13.2* – 1.5^ns 10.0^ns Closed −4.5^ns −3.7^ns 0.9^ns −10.8* −1.8* −1.3* 0.2^ns −2.3* −2.9^ns −22.8* – 1.5^ns – Both −2.9^ns −6.6^ns −3.6^ns −9.7^ns 0.0^ns 7.8^ns −0.7^ns −3.8^ns −2.6^ns −16.7* – 1.5^ns 10.0^ns Interval^b Open 35.8 28.0 25.6 25.8 7.2 27.6 8.4 22.9 12.1 19.9 – 26.1 35.2 Closed 18.8 10.1 8.0 18.3 1.9 2.1 1.4 4.3 13.2 20.5 – 11.6 – Both 27.2 21.1 19.9 20.3 5.9 23.5 6.3 16.8 10.4 18.9 – 19.5 35.2

[i] ^aSuperscripts of “ns”:, “*”, and “**” represent that averaged value was statistically no significant from the value by the control experiment (p>0.10), significant (p<0.05), and significant (0.05<p<0.10), respectively.

[ii] ^bInterval represent 90% confidence interval (t-distribution) of change in the annual flux associated with the each calculation option.

Annual evapotranspiration (ET) by the open-path system, the closed-path system and the closed-path system correcting humidity effect on the high-frequency loss (Mammarella et al., 2009). Since the flux measurement by the closed-path system was only conducted between DOY105 and 294 at MSE, ET is only compared for that period.

Difference between annual fluxes with and without the self-heating correction by Amiro (2010). Positive values represent an increase of the fluxes (decreased CO₂ uptake) after the correction.

Table A1. Data coverage (%) after the quality control to the total number of data point

Control NoDR PFR DRext TR NoWV NoCW NoDespike Detrend1 Detrend2 NoHL Average BRW H 75.4 69.8 68.8 71.8 68.7 75.5 75.4 66.1 78.5 79.4 75.4 73.2 LE 54.5 51.1 50.8 52.7 48.7 54.6 55.3 42.8 60.2 62.2 54.5 53.4 Fc 54.7 51.3 50.9 52.8 49.1 54.7 55.5 45.2 62.3 60.3 54.7 53.8 UAF H 50.8 61.4 56.5 56.3 49.8 51.5 – 50.5 55.6 57.5 50.8 54.1 LE 32.5 36.0 32.7 34.7 30.3 32.7 – 31.1 41.5 38.6 32.5 34.3 Fc 33.0 36.5 33.2 35.1 30.9 33.1 – 31.7 41.6 38.9 33.0 34.7 TSE open H 36.6 35.0 40.8 39.5 45.3 47.7 47.0 47.6 50.8 51.4 36.6 43.5 LE 23.5 23.7 26.3 25.9 29.4 31.1 30.9 28.6 28.5 28.8 23.5 27.3 Fc 23.7 23.9 26.5 26.1 29.7 31.3 31.1 28.8 29.0 28.7 23.7 27.5 TSE closed H 43.5 47.8 47.9 39.5 45.3 47.7 47.0 47.6 50.8 51.4 43.5 46.5 LE 45.0 50.8 50.7 42.1 47.7 49.8 50.1 49.3 49.2 49.6 46.9 48.3 Fc 42.6 47.6 47.6 41.2 45.1 46.8 46.9 46.1 42.6 43.0 42.6 44.7 TMK open H 64.5 61.2 64.9 64.5 60.3 54.3 64.8 64.7 67.6 68.7 64.5 63.6 LE 46.6 44.5 46.6 46.2 41.2 40.8 46.6 43.3 47.1 47.9 46.6 45.2 Fc 48.9 46.6 48.9 48.6 44.9 42.7 48.8 45.3 49.7 50.2 48.9 47.6 TMK closed H 64.5 61.2 64.9 64.5 60.3 54.3 64.8 64.7 67.6 68.7 64.5 63.6 LE 60.3 56.6 60.6 37.4 52.7 48.7 60.9 60.6 58.2 58.8 68.3 56.7 Fc 66.7 62.4 66.5 66.4 59.9 55.3 66.9 65.8 56.5 56.8 66.7 62.7 MSE open H 56.6 58.6 62.0 57.9 60.2 60.1 60.1 64.2 65.5 60.1 60.5 LE 50.5 47.5 49.4 51.7 48.4 50.7 50.5 49.3 54.8 56.1 50.5 50.8 Fc 50.7 47.8 49.7 52.0 48.9 50.9 50.7 49.5 54.9 56.2 50.7 51.1 MSE closed H 60.1 56.6 58.6 62.0 57.9 60.2 60.1 60.1 64.2 65.5 60.1 60.5 LE 46.0 43.3 46.9 48.7 43.4 46.0 46.5 45.8 47.4 48.4 61.5 47.6 Fc 60.2 57.8 61.0 62.4 56.7 60.2 60.2 59.6 62.6 63.6 60.2 60.4 FHK open H 47.3 46.5 46.6 48.2 42.6 46.9 41.5 47.3 51.4 52.9 47.3 47.1 LE 30.9 30.4 30.9 31.6 26.0 30.9 27.2 30.4 33.4 34.9 30.9 30.7 Fc 34.0 33.5 33.8 34.8 30.4 34.0 29.8 33.6 35.6 36.7 34.0 33.6 FHK closed H 47.3 46.5 46.6 48.2 42.6 46.9 41.5 47.3 51.4 52.9 47.3 47.1 LE 43.6 41.7 41.9 43.8 37.7 43.7 37.6 43.6 44.7 45.9 47.4 42.9 Fc 45.9 44.2 45.5 46.2 40.1 46.0 39.7 45.7 44.5 45.9 45.9 44.5 PDF H 56.8 56.3 57.0 57.5 54.6 56.6 – 47.3 59.3 60.5 56.8 56.3 LE 46.4 46.2 46.9 47.2 44.0 46.5 – 38.2 50.5 52.0 46.4 46.4 Fc 48.0 47.8 48.4 48.7 46.1 48.0 – 39.5 51.4 52.6 48.0 47.8 Average H 55.2 54.4 55.6 55.8 53.2 54.7 55.8 54.8 60.1 61.3 55.2 56.0 LE 43.6 42.9 44.0 42.0 40.9 43.2 45.1 42.1 46.9 47.6 46.3 44.0 Fc 46.2 45.4 46.5 46.8 43.8 45.7 47.8 44.6 48.3 48.4 46.2 46.2

Seasonal variations of NEE obtained by the open- and closed-path eddy covariance systems.

Uncertainties of the annual fluxes and u*-threshold caused by the flux calculation options. Points and bar charts represent the annual uncertainties for each site and mean, respectively, whereas vertical bars represents the 90% confidence interval. The uncertainties are categorized for the annual uncertainties associated with all of the corrections, except the self-heating and Mammarella corrections. The uncertainties from the standardized data are also shown in the figure, where the uncertainties at all recommended correction was applied (applying despiking, water vapor correction and crosswind correction, high-frequency loss and not applying detrending, TR, the self-heating correction and the Mammarella correction). Uncertainties for H, NEE and u*-threshold are shown as differences, whereas those for ET, GPP and RE are shown as relative values.

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DOI: https://doi.org/10.3402/tellusb.v64i0.19048 | Journal eISSN: 1600-0889

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Language: English

Page range: 19048 - 19048

Submitted on: Oct 30, 2011

Accepted on: Jun 7, 2012

Published on: Jan 1, 2012

Published by: Stockholm University Press

In partnership with: Paradigm Publishing Services

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© 2012 Masahito Ueyama, Ryuichi Hirata, Masayoshi Mano, Ken Hamotani, Yoshinobu Harazono, Takashi Hirano, Akira Miyata, Kentaro Takagi, Yoshiyuki Takahashi, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 64 (2012): Issue 1

Influences of various calculation options on heat, water and carbon fluxes determined by open- and closed-path eddy covariance methods

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