The Influence of Advection on the Short Term CO 2 -Budget in and Above a Forest Canopy

Feigenwinter, Christian; Bernhofer, Christian; Vogt, Roland

doi:10.1023/b:boun.0000039372.86053.ff

Cited by 152 publications

(170 citation statements)

References 26 publications

Supporting

Mentioning

161

Contrasting

Unclassified

Order By: Relevance

“…It is difficult to explore these processes via single tower measurements, though some theoretical and experimental attempts are presented in Assouline et al (2008) for heat and water vapour above small reservoirs. Recent studies (Feigenwinter et al 2004;Aubinet et al 2005;Sun et al 2007) found that advection may be significant even during daytime especially with low intensity turbulence. However, the main concern refers to nocturnal conditions when an underestimation of CO 2 fluxes using the eddy-covariance technique frequently occurs because non-turbulent transport processes, not taken into account by the eddy-covariance system, become significant.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest

Cava

Katul

Sempreviva

et al. 2008

Boundary-Layer Meteorol

View full text Add to dashboard Cite

Within the canopy sub-layer (CSL), variability in scalar sources and sinks are known to affect flux-variance (FV) similarity relationships for water vapour (q) and carbon dioxide (C) concentrations, yet large-scale processes may continue to play a significant role. High frequency time series data for temperature (T ), q and C, collected within the CSL of an uneven-aged mixed coniferous forest in Lavarone, Italy, are used to investigate these processes within the context of FV similarity. This dataset suggests that MOST scaling describes the FV similarity function of T even though the observations are collected in the CSL, consistent with other studies. However, the measured FV similarity functions for q and C appear to have higher values than their temperature counterpart. Two hypotheses are proposed to explain the measured anomalous behaviour in the FV similarity functions for q and C when referenced to T . Respired CO 2 from the forest floor leads to large positive excursions in the C time series at the canopy top thereby contributing significantly to both C variance increase and C vertical flux decrease-both leading to an anomalous increase in the FV similarity function. For q, transport of dry air from the outer-layer significantly increases both the variance and the water vapour flux. However, the expected flux increase is much smaller than the variance increase so that the net effect remains an increase in the measured FV similarity function for water vapour above its T counterpart. The hypothesis here is that identifying these events in the temporal and/or in the frequency domain and filtering them from the C and q time series partially recovers a scalar flow field that appears to follow FV similarity theory scaling. Methods for identifying both types of events in the time and frequency domains and their subsequent effects on the FV similarity functions and corollary flow variables, such as the relative transport efficiencies, are also explored.

show abstract

Section: Discussionmentioning

confidence: 99%

“…It is possible that departures from MOST scaling for FV may provide additional clues as to when CO 2 advection is important. However, Feigenwinter et al 2004, Aubinet et al 2005, Sun et al 2007 do not discuss the role of advection on FV similarity functions (only on CO 2 fluxes via the mean scalar continuity).…”

Section: Discussionmentioning

confidence: 99%

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest

Cava

Katul

Sempreviva

et al. 2008

Boundary-Layer Meteorol

View full text Add to dashboard Cite

show abstract

“…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%

“…Goulden et al, 1996;Suyker et al, 2005;Moureaux et al, 2006;Zhao et al, 2006); and (ii) the "correction approach", based on a direct estimation of all the CO 2 balance terms, including the advection terms (e.g. Aubinet et al, 2003Aubinet et al, , 2005Feigenwinter et al, 2004;Staebler and Fitzjarrald, 2004;Marcolla et al, 2005;Sun et al, 2007;Yi et al, 2008;Montagnani et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

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

View full text Add to dashboard Cite

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.

show abstract

“…In this context, advection is a highly discussed topic especially in relation to the net ecosystem exchange of CO 2 (e.g. Aubinet et al 2003;Baldocchi et al 2000a;Feigenwinter et al 2004;Lee 1998;Lee and Hu 2002;Paw U et al 2000;Staebler and Fitzjarrald 2004). It is also suspected and discussed that advection may contribute to the lack of energy closure (e.g.…”

Section: Introductionmentioning

confidence: 99%

Available energy and energy balance closure at four coniferous forest sites across Europe

Moderow

Aubinet

Feigenwinter

et al. 2009

Theor Appl Climatol

View full text Add to dashboard Cite

The available energy (AE), driving the turbulent fluxes of sensible heat and latent heat at the earth surface, was estimated at four partly complex coniferous forest sites across Europe (Tharandt, Germany; Ritten/Renon, Italy; Wetzstein, Germany; Norunda, Sweden). Existing data of net radiation were used as well as storage change rates calculated from temperature and humidity measurements to finally calculate the AE of all forest sites with uncertainty bounds. Data of the advection experiments MORE II (Tharandt) and ADVEX (Renon, Wetzstein, Norunda) served as the main basis. On-site data for referencing and cross-checking of the available energy were limited. Applied cross checks for net radiation (modelling, referencing to nearby stations and ratio of net radiation to global radiation) did not reveal relevant uncertainties. Heat storage of sensible heat J H , latent heat J E , heat storage of biomass J veg and heat storage due to photosynthesis J C were of minor importance during day but of some importance during night, where J veg turned out to be the most important one. Comparisons of calculated storage terms (J E , J H ) at different towers of one site showed good agreement indicating that storage change calculated at a single point is representative for the whole canopy at sites with moderate heterogeneity. The uncertainty in AE was assessed on the basis of literature values and the results of the applied cross checks for net radiation. The absolute mean uncertainty of AE was estimated to be between 41 and 52 W m −2 (10-11 W m −2 for the sum of the storage terms J and soil heat flux G) during mid-day (approximately 12% of AE). At night, the absolute mean uncertainty of AE varied from 20 to about 30 W m −2 (approximately 6 W m −2 for J plus G) resulting in large relative uncertainties as AE itself is small. An inspection of the energy balance showed an improvement of closure when storage terms were included and that the imbalance cannot be attributed to the uncertainties in AE alone.

show abstract

The Influence of Advection on the Short Term CO 2 -Budget in and Above a Forest Canopy

Cited by 152 publications

References 26 publications

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest

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

Available energy and energy balance closure at four coniferous forest sites across Europe

Contact Info

Product

Resources

About