An intercomparison of surface energy flux measurement systems used during FIFE 1987

Nie, D.; Kanemasu, E. T.; Fritschen, Leo J.; Weaver, H. L.; Smith, Eric A.; Verma, S. B.; Field, R. T.; Kustas, W. P.; Stewart, J. B.

doi:10.1029/91jd03044

Cited by 69 publications

(29 citation statements)

References 6 publications

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“…During the FIFE experiment, Nie et al (1992) found that the four flux components measured by an EC system summed to a maximum residual of 160 W m −2 . An EC system and EBBR system were collocated at site 926 for 3 days.…”

Section: Review Of Surface Flux Measurements and Energy-balance Closurementioning

confidence: 99%

“…The importance of accurate micrometeorological measurements of surface fluxes is a justification for long-term flux measurement networks (Baldocchi et al, 1996). Unfortunately, the micrometeorological literature contains numerous anecdotal references to possible systematic underestimates of surface scalar fluxes by the preferred measurement system; namely eddy covariance (Dugas et al, 1991;Nie et al, 1992;Fritschen et al, 1992;Goulden et al, 1997;McCaughey et al, 1997;Mahrt, 1998). The potential problems that systematic errors can create in long-term surface flux measurements, particularly selective systematic errors (different daytime errors from night-time errors), are considered by Moncrief et al (1996) and can be serious.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Correcting eddy-covariance flux underestimates over a grassland

Twine¹,

Kustas²,

Norman³

et al. 2000

Agricultural and Forest Meteorology

1,635

1,114

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Twine, T. E.; Kustas, W. P.; Norman, J. M.; Cook, D. R.; Houser, P. R.; Meyers, T. P.; Prueger, J. H.; Starks, P. J.; and Wesley, M. L., "Correcting eddy-covariance flux underestimates over a grassland" (2000). AbstractIndependent measurements of the major energy balance flux components are not often consistent with the principle of conservation of energy. This is referred to as a lack of closure of the surface energy balance. Most results in the literature have shown the sum of sensible and latent heat fluxes measured by eddy covariance to be less than the difference between net radiation and soil heat fluxes. This under-measurement of sensible and latent heat fluxes by eddy-covariance instruments has occurred in numerous field experiments and among many different manufacturers of instruments. Four eddy-covariance systems consisting of the same models of instruments were set up side-by-side during the Southern Great Plains 1997 Hydrology Experiment and all systems under-measured fluxes by similar amounts. One of these eddy-covariance systems was collocated with three other types of eddy-covariance systems at different sites; all of these systems under-measured the sensible and latent-heat fluxes. The net radiometers and soil heat flux plates used in conjunction with the eddy-covariance systems were calibrated independently and measurements of net radiation and soil heat flux showed little scatter for various sites. The 10% absolute uncertainty in available energy measurements was considerably smaller than the systematic closure problem in the surface energy budget, which varied from 10 to 30%. When available-energy measurement errors are known and modest, eddy-covariance measurements of sensible and latent heat fluxes should be adjusted for closure. Although the preferred method of energy balance closure is to maintain the Bowen-ratio, the method for obtaining closure appears to be less important than assuring that eddy-covariance measurements are consistent with conservation of energy. Based on numerous measurements over a sorghum canopy, carbon dioxide fluxes, which are measured by eddy covariance, are underestimated by the same factor as eddy covariance evaporation measurements when energy balance closure is not achieved. Published by Elsevier Science B.V.

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Section: Review Of Surface Flux Measurements and Energy-balance Closurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Correcting eddy-covariance flux underestimates over a grassland

Twine¹,

Kustas²,

Norman³

et al. 2000

Agricultural and Forest Meteorology

1,635

1,114

View full text Add to dashboard Cite

show abstract

“…That is, the observed net radiation is usually greater than the sum of the observed sensible heat, the latent heat and the surface soil heat. Nie et al (1992) found that the maximum residual energy could reach 160 Wm À2 during the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE), and that eddy correlation systems gave slightly lower latent heat fluxes in comparison with the Bowen ratio systems. McCaughey et al (1997) reported that the average daily energy budget closure ðH þ lEÞ/ ðR n À G 0 Þ varied from 0.85 to 0.95 for forest sites of the BOREAS (Boreal EcosystemAtmosphere Study) experiment.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Surface Energy Budget at a Site of GAME/Tibet using a Single-Source Model

Yang

Koike

Ishikawa

et al. 2004

Journal of the Meteorological Society of Japan

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In the GAME/Tibet project, the Anduo site is a typical plateau prairie area that is covered by short and sparse vegetation. From May to September 1998, we measured all the surface energy fluxes at this site to quantitatively describe the surface energy budget, but it was still questionable because of low energy closure ratios in most days of the rainy season.To clarify the surface energy budget at this site, this study proposes a single-source energy partition model, to simplify the processes of heat and water vapor transfer from the surface. The model does not distinguish the contribution of turbulent fluxes from the vegetation, and the one from the ground, and thus has fewer parameters to be calibrated comparing to a dual-source model. The main model parameters are: the soil surface evaporation resistance, the parameter kB À1 (the logarithm of the ratio of the aerodynamic roughness length to the thermal roughness length), and the surface emissivity. Their values are calibrated by minimizing the discrepancy between measured and model-predicted values of soil temperatures.This tuned single-source model is then validated by the agreement between the measured and simulated net radiation flux, surface soil heat flux, sensible heat flux, and latent heat flux on the days with high energy closure ratios. This model also reproduces these measured fluxes, except latent heat flux on the days with low closure ratios. The simulated latent heat flux is much higher than the measured one. We further show that the measured latent heat flux is untrustable due to an instrumental limitation, while the model provides a reasonable surrogate. Therefore, the single-source concept is applicable to the heat and water vapor transfer on the Tibetan plateau sparse-vegetation surface, and would contribute to a further research on the land-atmosphere interactions over the plateau.

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“…The closure issue becomes even more important upon consideration of the long-term water balance. Twine et al (2000) summed over a period of 15 days from 4 EC systems and drew a conclusion that evapotranspiration would be significantly overestimated by calculating LE as the residual of the energy budget; this is also supported by others (Dugas et al 1991;Kampf et al 2005;Nie et al 1992). Thus, in our study, it is a risk to use the EC residual method to estimate LE since there were more uncertainties from R n , G, S, and other heat sinks, especially when LE is smaller or under a certain spatial scale.…”

Section: Potential Causes Of R N Measurements For Non-closurementioning

confidence: 70%

Spatial variation of net radiation and its contribution to energy balance closures in grassland ecosystems

Shao

Dong

et al. 2014

Ecol Process

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Introduction: Low energy balance closure (EBC) at a particular eddy-covariance flux site has increased the uncertainties of carbon, water, and energy measurements and has thus hampered the urgent research of scaling up and modeling analyses through site combinations in regional or global flux networks. Methods: A series of manipulative experiments were conducted in this study to explore the role of net radiation (R n ) in the EBC in relation to spatial variability of vegetation characteristics, source area, and sensor type in three sites of the Inner Mongolian grassland of northern China.

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An intercomparison of surface energy flux measurement systems used during FIFE 1987

Cited by 69 publications

References 6 publications

Correcting eddy-covariance flux underestimates over a grassland

Correcting eddy-covariance flux underestimates over a grassland

Analysis of the Surface Energy Budget at a Site of GAME/Tibet using a Single-Source Model

Spatial variation of net radiation and its contribution to energy balance closures in grassland ecosystems

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