An Investigation of the Conditional Sampling Method Used to Estimate Fluxes of Active, Reactive, and Passive Scalars

Katul, Gabriel G.; Finkelstein, Peter L.; Clarke, J. F.; Ellestad, T.G.

doi:10.1175/1520-0450(1996)035<1835:aiotcs>2.0.co;2

Cited by 82 publications

(100 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A few cases for which b < 0 were discarded, since the REA, similarly to flux-gradient methods, cannot cope with countergradient fluxes. Our data do not show any significant dependency of b on ζ , in agreement with Katul et al (1996) and Businger and Oncley (1990).…”

Section: Relaxed Eddy Accumulationsupporting

confidence: 91%

“…All the means are in the same range found by other authors (e.g., 0.51-0.62 by Katul et al, 1996), which incidentally are values obtained for the surface layer above the roughness sublayer. The scatter in our data, however, is larger: at 81.6 m it reaches 0.71 for b c .…”

Section: Relaxed Eddy Accumulationsupporting

confidence: 87%

“…REA coefficients measured above the roughness sublayer, where z is the measurement height (in meters) and numbers between brackets are the height of the canopies. Businger and Oncley (1990) Katul et al (1996) Baker et al (1992) z ( We find that, close to the canopy top, at 39.4 m, the integral scale L often far exceeds κ(z − d): this means that the latter is not a good estimate of the integral scale, as often found in the roughness sublayer. These results are in agreement with the findings by Rao et al (1973) and Mammarella et al (2008).…”

Section: Dissipation Ratesmentioning

confidence: 80%

“…where σ w is the standard deviation of the vertical velocity and b c is the relaxation coefficient, which is empirically verified to be a dimensionless constant (it could be a MOST similarity function) of the order of 0.6 (Businger and Oncley, 1990;Katul et al, 1996). Although initially developed and tested for the measurement of CO 2 , water vapor, and sensible heat fluxes (Pattey et al, 1993;Bash and Miller, 2007), the REA method is often extended for the measurement of other gaseous or scalar fluxes, usually with direct sensible or latent heat fluxes used as proxies to estimate b.…”

Section: The Relaxed Eddy Accumulation Methods and Related Analysesmentioning

confidence: 99%

See 3 more Smart Citations

Scalar turbulent behavior in the roughness sublayer of an Amazonian forest

Zahn¹,

Dias²,

Araújo³

et al. 2016

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. An important current problem in micrometeorology is the characterization of turbulence in the roughness sublayer (RSL), where most of the measurements above tall forests are made. There, scalar turbulent fluctuations display significant departures from the predictions of MoninObukhov similarity theory (MOST). In this work, we analyze turbulence data of virtual temperature, carbon dioxide, and water vapor in the RSL above an Amazonian forest (with a canopy height of 40 m), measured at 39.4 and 81.6 m above the ground under unstable conditions. We found that dimensionless statistics related to the rate of dissipation of turbulence kinetic energy (TKE) and the scalar variance display significant departures from MOST as expected, whereas the vertical velocity variance follows MOST much more closely. Much better agreement between the dimensionless statistics with the Obukhov similarity variable, however, was found for the subset of measurements made at a low zenith angle Z, in the range 0 • < |Z| < 20 • . We conjecture that this improvement is due to the relationship between sunlight incidence and the "activation-deactivation" of scalar sinks and sources vertically distributed in the forest. Finally, we evaluated the relaxation coefficient of relaxed eddy accumulation: it is also affected by zenith angle, with considerable improvement in the range 0 • < |Z| < 20 • , and its values fall within the range reported in the literature for the unstable surface layer. In general, our results indicate the possibility of better stability-derived flux estimates for low zenith angle ranges.

show abstract

Section: Relaxed Eddy Accumulationsupporting

confidence: 91%

Section: Relaxed Eddy Accumulationsupporting

confidence: 87%

Section: Dissipation Ratesmentioning

confidence: 80%

Section: The Relaxed Eddy Accumulation Methods and Related Analysesmentioning

confidence: 99%

See 2 more Smart Citations

Scalar turbulent behavior in the roughness sublayer of an Amazonian forest

Zahn¹,

Dias²,

Araújo³

et al. 2016

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…For an ideal Gaussian joint frequency distribution (JFD) of the vertical wind speed and the mixing ratio of the scalar, b is constant (b = 0.627; Baker et al, 1992;Wyngaard and Moeng, 1992). But variations in b can be generated by just a small skewness of the JFD of w and c (Katul et al, 1996;Fotiadi et al, 2005;Ruppert et al, 2006b), the application to different trace gases (Businger and Oncley, 1990;Baker et al, 1992;Oncley et al, 1993;Pattey et al, 1993) or the use in different ecosystem compartments (Gao, 1995). b may also vary significantly during individual 30 min integration intervals (Businger and Oncley, 1990;Baker et al, 1992;Oncley et al, 1993;Pattey et al, 1993;Beverland et al, 1996;Katul et al, 1996;Bowling et al, 1999a;Ammann and Meixner, 2002;Ruppert et al, 2006b).…”

Section: Rea Theory and Frameworkmentioning

confidence: 99%

Prerequisites for application of hyperbolic relaxed eddy accumulation on managed grasslands and alternative net ecosystem exchange flux partitioning

et al. 2014

View full text Add to dashboard Cite

Abstract.Relaxed eddy accumulation is still applied in ecosystem sciences for measuring trace gas fluxes. On managed grasslands, the length of time between management events and the application of relaxed eddy accumulation has an essential influence on the determination of the proportionality factor b and thus on the resulting flux. In this study this effect is discussed for the first time. Also, scalar similarity between proxy scalars and scalars of interest is affected until the ecosystem has completely recovered. Against this background, CO 2 fluxes were continuously measured and 13 CO 2 isofluxes were determined with a high measurement precision on two representative days in summer 2010.Moreover, a common method for the partitioning of the net ecosystem exchange into assimilation and respiration based on temperature and light response was compared with an isotopic approach directly based on the isotope discrimination of the biosphere. This approach worked well on the grassland site and could enhance flux partitioning results by better reproducing the environmental conditions.

show abstract

Ultrafine particle number fluxes over and in a deciduous forest

et al. 2017

View full text Add to dashboard Cite

Ultrafine particles (UFP, particles with diameters (Dp) < 100 nm) play a key role in climate forcing; thus, there is interest in improved understanding of atmosphere‐surface exchange of these particles. Long‐term flux measurements from a deciduous forest in the Midwestern USA (taken during December 2012 to May 2014) show that although a substantial fraction of the data period indicates upward fluxes of UFP, on average, the forest is a net sink for UFP during both leaf‐active and leaf‐off periods. The overall mean above‐canopy UFP number flux computed from this large data set is −4.90 × 106 m−2 s−1 which re‐emphasizes the importance of these ecosystems to UFP removal from the atmosphere. Although there remain major challenges to accurate estimation of the UFP number flux and in drawing inferences regarding the actual surface exchange from measurements taken above the canopy, the above the canopy mean flux is shown to be downward throughout the day (except at 23.00) with largest‐magnitude fluxes during the middle of the day. On average, nearly three quarters of the total UFP capture by this ecosystem occurs at the canopy. This fraction increases to 78% during the leaf‐active period, but the over‐storey remains dominant over the subcanopy even during the leaf‐off period.

show abstract

An Investigation of the Conditional Sampling Method Used to Estimate Fluxes of Active, Reactive, and Passive Scalars

Cited by 82 publications

References 31 publications

Scalar turbulent behavior in the roughness sublayer of an Amazonian forest

Scalar turbulent behavior in the roughness sublayer of an Amazonian forest

Prerequisites for application of hyperbolic relaxed eddy accumulation on managed grasslands and alternative net ecosystem exchange flux partitioning

Ultrafine particle number fluxes over and in a deciduous forest

Contact Info

Product

Resources

About