The Measurement of Vertical Transfer of Heat and Water Vapor by Eddies in the Lower Atmosphere

Swinbank, W. C.

doi:10.1175/1520-0469(1951)008<0135:tmovto>2.0.co;2

Cited by 343 publications

(170 citation statements)

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“…Eddies are turbulent airflow caused by wind, surface roughness, and convective heat flow in the atmospheric surface layer (Swinbank, 1951;Brutsaert, 1982;Kaimal and Finnigan, 1994). Eddies transfer energy and mass between land and water surfaces and the atmosphere through a process referred to as turbulent exchange, or turbulent transport (Brutsaert, 1982).…”

Section: Eddy Covariancementioning

confidence: 99%

Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012

Moreo¹,

Swancar²

2013

Scientific Investigations Report

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Section: Eddy Covariancementioning

confidence: 99%

Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012

Moreo¹,

Swancar²

2013

Scientific Investigations Report

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“…One of them is that procedures for calculating fluxes from raw data must be refined to minimize errors and uncertainties that may be unique to aquatic applications. The procedures used today are largely adapted directly from atmospheric boundary layer research, where the eddy covariance technique has been used for more than 6 decades (Priestley and Swinbank, 1947;Swinbank, 1951).…”

Section: Introductionmentioning

confidence: 99%

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

et al. 2015

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Abstract. Extracting benthic oxygen fluxes from eddy covariance time series measured in the presence of surface gravity waves requires careful consideration of the temporal alignment of the vertical velocity and the oxygen concentration. Using a model based on linear wave theory and measured eddy covariance data, we show that a substantial error in flux can arise if these two variables are not aligned correctly in time. We refer to this error in flux as the time lag bias. In one example, produced with the wave model, we found that an offset of 0.25 s between the oxygen and the velocity data produced a 2-fold overestimation of the flux. In another example, relying on nighttime data measured over a seagrass meadow, a similar offset reversed the flux from an uptake of −50 mmol m −2 d −1 to a release of 40 mmol m −2 d −1 . The bias is most acute for data measured at shallow-water sites with short-period waves and low current velocities. At moderate or higher current velocities (> 5-10 cm s −1 ), the bias is usually insignificant. The widely used traditional time shift correction for data measured in unidirectional flows, where the maximum numerical flux is sought, should not be applied in the presence of waves because it tends to maximize the time lag bias or give unrealistic flux estimates. Based on wave model predictions and measured data, we propose a new time lag correction that minimizes the time lag bias. The correction requires that the time series of both vertical velocity and oxygen concentration contain a clear periodic wave signal. Because wave motions are often evident in eddy covariance data measured at shallow-water sites, we encourage more work on identifying new time lag corrections.

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“…The best widely available method for measuring canopy or ecosystem mass and energy exchange, and therefore testing canopy or community physiology models, is eddy correlation. Eddy correlation is a micrometeorological technique, first applied by Swinbank (1951), that measures the net exchange of an entity above an ecosystem with approximately &20% accuracy over areas extending several tens to hundreds of meters upwind of the instrument tower (Brutsaert 1982;Baldocchi et al 1988;Dabberdt et al 1993). Eddy correlation measurements of ecosystem C 0 2 exchange have generally been confined to short periods, i.e.…”

Section: Introductionmentioning

confidence: 99%

Testing a Mechanistic Model of Forest-Canopy Mass and Energy Exchange Using Eddy Correlation: Carbon Dioxide and Ozone Uptake by a Mixed Oak-Maple Stand

Amthor¹,

Goulden²,

Munger³

et al. 1994

Functional Plant Biol.

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A big-leaf model of C3-canopy mass and energy exchange was used to predict hourly C02 and O3 uptake by a mixed deciduous Quercus-Acer (oak-maple) stand in central Massachusetts, USA. The model is based on canopy-radiation interactions, leaf mesophyll metabolism (photosynthetic electron transport, carboxylation and oxygenation of ribulose 1,s-bisphosphate [RuP2] by RuPz carboxylase/oxygenase [Rubisco], and respiration), physical transport conductances of mass and heat above and within the canopy, conductances of mass at the leaf surface and in the mesophyll, and mass and energy exchange at the soil surface (forest floor). Predictions of hourly C02 and O3 uptake were compared to independent whole-forest C02 and O3 exchange measurements made by the eddy correlation method during a 68 day period in the summer and early autumn of 1992. Predicted hourly C02 exchange rate was strongly correlated (r --+0.91) with measured hourly COz exchange, but mean day-time predicted whole-forest C02 uptake was c. 13% (c. 1.13 pmol C 0 2 m-2 s-') greater than C 0 2 uptake measured by eddy correlation. The model tended to overpredict C02 uptake during late afternoon, but was accurate during the rest of the day. Predicted and measured O3 uptake rates also were positively correlated (r * +0.76). The diurnal patterns of predicted and measured O3 uptake indicated that stomata1 conductance (g,) was accurately predicted during the morning, but in the afternoon the model overpredicted g,. This pattern was consistent with the overprediction of afternoon C 0 2 uptake, and suggested that a feedback inhibition of photosynthesis occurred in the afternoon. This might have been related to source-sink imbalance following several hours of photosynthesis. On the whole, and in spite of the simplifications inherent in the big-leaf representation of the canopy, the model is useful for predicting forest-environment interactions and for interpreting mass and energy exchange measurements.

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The Measurement of Vertical Transfer of Heat and Water Vapor by Eddies in the Lower Atmosphere

Cited by 343 publications

References 0 publications

Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012

Evaporation from Lake Mead, Nevada and Arizona, March 2010 through February 2012

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

Testing a Mechanistic Model of Forest-Canopy Mass and Energy Exchange Using Eddy Correlation: Carbon Dioxide and Ozone Uptake by a Mixed Oak-Maple Stand

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