The Effect of Surface Heterogeneity on the Temperature–Humidity Correlation and the Relative Transport Efficiency

Moene, Arnold F.; Schüttemeyer, Dirk

doi:10.1007/s10546-008-9312-z

Cited by 32 publications

(28 citation statements)

References 20 publications

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“…4). In comparison, our data better fit the predictions of the conceptual model of Moene and Schüttemeyer (2008), taking into account the vegetative heterogeneity (as a characteristic of our experiment site).…”

Section: Behaviour Of λ θQ and The Latent Heat Flux Estimationsupporting

confidence: 76%

“…Thus, the K − β relationship is likely to vary from site to site and needs local determination (cf. Moene and Schüttemeyer 2008). Likewise, the M − α relationship has to be further examined.…”

Section: Discussionmentioning

confidence: 99%

“…20 and 21). Here, α can be regarded as a 'logical equivalent' to the Bowen ratio (β), which is theoretically pursued and numerically analyzed by Moene and Schüttemeyer (2008) using a conceptual model. Figure 7 shows the relationship between the power M in Eq.…”

Section: Behaviour Of λ θ C and Co 2 Flux Estimationmentioning

confidence: 99%

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Flux-Variance Method for Latent Heat and Carbon Dioxide Fluxes in Unstable Conditions

Guo

Zhang

Cai

et al. 2009

Boundary-Layer Meteorol

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Applied previously to momentum and heat fluxes, the present study extends the flux-variance method to latent heat and CO 2 fluxes in unstable conditions. Scalar similarity is also examined among temperature (θ ), water vapour (q), and CO 2 (c). Temperature is adopted as the reference scalar, leading to two feasible strategies to estimate latent heat and CO 2 fluxes: the first one relies on flux-variance similarity relations for scalars, while the second is based on the parameterization of relative transport efficiency in terms of scalar correlation coefficient and a non-dimensional quantity. The relationship between the θ -to-q transport efficiency (λ θq ) and θ -q correlation coefficient (R θq ) is used to describe the intermediate hydrological conditions. We also parameterize the θ -to-c transport efficiency (λ θ c ) as a function of the θ -c correlation coefficient (R θ c ) by introducing a new non-dimensional ratio (α). The flux-variance method is a viable technique for flux gap-filling, when turbulence measurements of wind velocity are not available. It is worth noting that the extended method is not exempt from a correction for density effects when used for estimating water or carbon exchange.

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Section: Behaviour Of λ θQ and The Latent Heat Flux Estimationsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Flux-Variance Method for Latent Heat and Carbon Dioxide Fluxes in Unstable Conditions

Guo

Zhang

Cai

et al. 2009

Boundary-Layer Meteorol

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“…The contrast between patches of hot, dry impervious areas and cool, wet vegetation may be reduced by altogether wetter surfaces in 2012, which is thought to increase correlation between temperature and humidity (Lamaud and Irvine, 2006;Moene and Schüttemeyer, 2008;Ramamurthy and Bou-Zeid, 2014). On the other hand, Lüdi et al (2005) found lower r T q coincides with lower β.…”

Section: Temperature-humidity Correlationmentioning

confidence: 98%

Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

et al. 2015

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Abstract. Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations, and the correlation between wavelengths is also used to retrieve the path-averaged temperature-humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the measurement techniques under different conditions is discussed. Similar behaviour is seen between the two data sets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1) compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the companion paper.

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“…Even then, it should be noted that the entrainment ratio and thus the importance of greater heights may vary between scalars (Moene et al 2006b). In comparatively dry conditions, the heterogeneity of the latent heat flux at the surface is larger than that of the sensible heat flux (Moene and Schüttemeyer 2008), adding further uncertainty and changing the local entrainment ratio even if the absolute entrainment flux is constant.…”

Section: Possible Extensions To Passive Scalarsmentioning

confidence: 99%

Boundedness of Turbulent Temperature Probability Distributions, and their Relation to the Vertical Profile in the Convective Boundary Layer

Graf

Schüttemeyer

Geiss

et al. 2009

Boundary-Layer Meteorol

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Higher-order moments, minima and maxima of turbulent temperature and water vapour mixing ratio probability density functions measured with an eddy-covariance system near the ground were related to each other and to vertical boundary-layer profiles of the same scalars obtained through airborne soundings. The dependence of kurtosis on squared skewness showed a kurtosis intercept below the Gaussian expectation, suggesting a compression of the probability density function by the presence of natural boundaries. This hypothesis was corroborated by comparing actual minima and maxima of turbulent fluctuations to estimates obtained from the first four sample moments by fitting a four-parameter beta distribution. The most sharply defined boundaries were found for the minima of temperature datasets during the day, indicating that negative temperature fluctuations at the sensor are limited by the availability of lower temperatures in the boundary layer. By comparison to vertical profiles, it could be verified that the turbulent minimum of temperature near the ground is close to the minimum of potential temperature in the boundary layer. The turbulent minimum of water vapour mixing ratio was found to be equal to the mixing ratio at a height above the minimum of the temperature profile. This height roughly agrees with the top of the non-local A. Graf (B) · M. Herbst · H. Vereecken Agrosphere (ICG-4), 123 460 A. Graf et al.unstable domain according to bulk Richardson number profiles. We conclude that turbulence statistics measured near the surface cannot be solely explained by local effects, but contain information about the whole boundary layer including the entrainment zone.

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The Effect of Surface Heterogeneity on the Temperature–Humidity Correlation and the Relative Transport Efficiency

Cited by 32 publications

References 20 publications

Flux-Variance Method for Latent Heat and Carbon Dioxide Fluxes in Unstable Conditions

Flux-Variance Method for Latent Heat and Carbon Dioxide Fluxes in Unstable Conditions

Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

Boundedness of Turbulent Temperature Probability Distributions, and their Relation to the Vertical Profile in the Convective Boundary Layer

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