Comparison of horizontal and vertical advective CO2 fluxes at three forest sites

Feigenwinter, Christian; Bernhofer, Christian; Eichelmann, Uwe; Heinesch, Bernard; Hertel, Martin; Janouš, Dalibor; Kolle, Olaf; Lagergren, Frederik; Lindroth, Anders; Minerbi, Stefano; Moderow, Uta; Mölder, Meelis; Montagnani, Leonardo; Queck, Ronald; Rebmann, Corinna; Vestin, Patrik; Yernaux, Michel; Zeri, Marcelo; Ziegler, W.; Aubinet, Marc

doi:10.1016/j.agrformet.2007.08.013

Cited by 149 publications

(139 citation statements)

References 34 publications

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“…We highlight that we do not treat separately vertical and horizontal advective flux terms -e.g., as Feigenwinter et al (2008) and the majority of the works about advection terms -but we calculate their sum directly. The uncertainties involved in the separate calculation of vertical and horizontal advection are related, among others, also to terrain slope estimation.…”

Section: Advection Term Calculationmentioning

confidence: 99%

“…Half hourly means of the measured variables were used further for the calculations, following both Feigenwinter et al (2008), where the same data were analysed, and other studies for FLUXNET sites (e.g., Feigenwinter et al, 2004;Aubinet et al, 2005;Heinesch et al, 2007;Turnipseed et al, 2004, Staebler andFitzjarrald, 2004;Yi et al, 2008).…”

Section: Procedures To Calculate the 3-d Fields Of The Physical Quantmentioning

confidence: 99%

“…As a test case, we studied six different 24-hour time periods, all these periods were studied in both Montagnani et al (2009) andFeigenwinter et al (2008) as well: 1 ) two periods characterised by "Tramontana", day of year (doy) 183-184 and 192-193; 2) two periods characterised by southerly wind, doy 205-206 and 207-208; 3) two periods characterised by the local slope wind system, resulting in downslope wind (near northerly) during the night, and upslope wind (near southerly) during the day, doy 209-210 and 210-211.…”

Section: Fig 3 Flowchart For the Computation Of Total Advective Fluxmentioning

confidence: 99%

“…The ADVEX extensive measurement campaign was performed during 133 days from May to September 2005 at the CarboEurope Renon/Ritten site (e.g., Feigenwinter et al, 2008 ;Montagnani et al, 2009). The site is situated at 1735 m a.s.l.…”

Section: Description Of the Measurement Site And The Study Periodsmentioning

confidence: 99%

“…1, top). A detailed description of the flux measurement system is given by Feigenwinter et al (2008). Montagnani et al, 2009)…”

Section: Introductionmentioning

confidence: 99%

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Application of a mass consistent flow model to study the CO2 mass balance of forests

Canepa

Georgieva

Manca

et al. 2010

Agricultural and Forest Meteorology

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The reconstruction of the wind field is one of the main issues in the mass conservation approach for calculation of CO 2 advection in forest ecosystems and still remains a challenging problem. In the current study, we present an advancement of this approach: the use of a mass consistent flow model (WINDS) which takes into account measured wind data and simulates the 3-D flow field, while imposing air mass conservation in the control volume. We apply the WINDS model to calculate half hourly mean total advective flux terms at the arboEurope-IP site of Renon (Bozen/Bolzano Autonomous Province), in Northern Italy. The data used refer to six time periods of one day representing three different meteorological conditions observed during the ADVEX campaign from April to September 2005. Current results are compared with results obtained in two other studies for the same time periods. One of these studies is based on the mass conservation approach as well, but applies only interpolations to reconstruct the wind field; the other study makes use of tilt correction (sectorwise planar fit method) for the vertical wind component. In the present study, the effect of the wind field reconstruction method on the estimation of the advective fluxes is discussed. The possibility of using reduced input wind data (i.e. number of towers) for WINDS is also investigated. The results suggest that the representativeness of wind tower measurements is of primary importance for estimating CO 2 advection terms and their uncertainty in complex terrain.

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Section: Advection Term Calculationmentioning

confidence: 99%

Section: Procedures To Calculate the 3-d Fields Of The Physical Quantmentioning

confidence: 99%

Section: Fig 3 Flowchart For the Computation Of Total Advective Fluxmentioning

confidence: 99%

Section: Description Of the Measurement Site And The Study Periodsmentioning

confidence: 99%

“…1, top). A detailed description of the flux measurement system is given by Feigenwinter et al (2008). Montagnani et al, 2009)…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Application of a mass consistent flow model to study the CO2 mass balance of forests

Canepa

Georgieva

Manca

et al. 2010

Agricultural and Forest Meteorology

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Accounting for vegetation height and wind direction to correct eddy covariance measurements of energy fluxes over hilly crop fields

et al. 2015

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As agricultural hilly watersheds are widespread throughout the world, there is a strong need for reliable estimates of land surface fluxes, especially evapotranspiration, over crop fields on hilly slopes. In order to obtain reliable estimates from eddy covariance (EC) measurements in such conditions, the current study aimed at proposing adequate planar fit tilt corrections that account for the combined effects of topography, wind direction, and vegetation height on airflow inclinations. EC measurements were collected within an agricultural hilly watershed in northeastern Tunisia, throughout the growth cycles of cereals, legumes, and pasture. The wind had two dominant directions that induced upslope and downslope winds. For upslope winds, the airflows were parallel to the slopes and slightly came closer to the horizontal plane when vegetation grew. For downslope winds, over fields located in the lee of the rim top, the airflows were almost horizontal over bare soil and came closer to the topographical slope when vegetation grew. We therefore adjusted the planar fit tilt correction on EC measurements according to vegetation height and by discriminating between upslope and downslope winds. This adjusted tilt correction improved the energy balance closure in most cases, and the obtained energy balance closures were similar to that reported in the literature for flat conditions. We conclude that EC data collected within crop fields on hilly slopes can be used for monitoring land surface fluxes, provided planar fit tilt corrections are applied in an appropriate manner.

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Impact of Canopy Decoupling and Subcanopy Advection on the Annual Carbon Balance of a Boreal Scots Pine Forest as Derived From Eddy Covariance

et al. 2018

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Apparent net uptake of carbon dioxide (CO2) during wintertime by an ∼ 90 year old Scots pine stand in northern Sweden led us to conduct canopy decoupling and subcanopy advection investigations over an entire year. Eddy covariance (EC) measurements ran simultaneously above and within the forest canopy for that purpose. We used the correlation of above‐ and below‐canopy standard deviation of vertical wind speed (σw) as decoupling indicator. We identified 0.33 m s−1 and 0.06 m s−1 as site‐specific σw thresholds for above‐ and below‐canopy coupling during nighttime (global radiation <20 W m−2) and 0.23 m s−1 and 0.06 m s−1 as daytime (global radiation >20 W m−2) σw thresholds. Decoupling occurred in 53% of the annual nighttime and 14% of the annual daytime. The annual net ecosystem exchange (NEE), gross ecosystem exchange (GEE), and ecosystem respiration (Reco) derived via two‐level filtered EC data were −357 g C m−2, −1,138 g C m−2, and 781 g C m−2, respectively. In comparison, both single‐level friction velocity (u*) and quality filtering resulted in ~ 22% higher NEE, mainly caused by ~ 16% lower Reco. GEE remained similar among filtering regimes. Accounting for changes of CO2 storage across the canopy in the single‐level filtered data could only marginally decrease these discrepancies. Consequently, advection appears to be responsible for the major part of this divergence. We conclude that the two‐level filter is necessary to adequately address decoupling and subcanopy advection at our site, and we recommend this filter for all forested EC sites.

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Comparison of horizontal and vertical advective CO2 fluxes at three forest sites

Cited by 149 publications

References 34 publications

Application of a mass consistent flow model to study the CO2 mass balance of forests

Application of a mass consistent flow model to study the CO2 mass balance of forests

Accounting for vegetation height and wind direction to correct eddy covariance measurements of energy fluxes over hilly crop fields

Impact of Canopy Decoupling and Subcanopy Advection on the Annual Carbon Balance of a Boreal Scots Pine Forest as Derived From Eddy Covariance

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