Variance Method to Determine Turbulent Fluxes of Momentum And Sensible Heat in The Stable Atmospheric Surface Layer

Bruin, H.A.R. de; Hartogensis, Oscar

doi:10.1007/s10546-004-1986-2

Cited by 13 publications

(7 citation statements)

References 23 publications

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“…It is seen that the e and C T 2 scaling performs well under these circumstances. De Bruin and Hartogensis (2005) show the same plot for the scaling of the standard deviation of temperature and longitudinal component of the wind speed, r T and r u , i.e. the variance method, which give less good results than the e and C T 2 scaling.…”

Section: Fluxes From E and C T 2 In Intermittent Turbulent Conditionsmentioning

confidence: 95%

Monin–Obukhov Similarity Functions of the Structure Parameter of Temperature and Turbulent Kinetic Energy Dissipation Rate in the Stable Boundary Layer

Hartogensis

Bruin

2005

Boundary-Layer Meteorol

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Abstract. The Monin-Obukhov similarity theory (MOST) functions f e and f T , of the dissipation rate of turbulent kinetic energy (TKE), e, and the structure parameter of temperature, C T 2 , were determined for the stable atmospheric surface layer using data gathered in the context of CASES-99. These data cover a relatively wide stability range, i.e. f ¼ z/L of up to 10, where z is the height and L the Obukhov length. The best fits were given by f e ¼ 0:8 þ 2:5f and f T ¼ 4:7½1 þ 1:6ðfÞ 2=3 ; which differ somewhat from previously published functions. e was obtained from spectra of the longitudinal wind velocity using a time series model (ARMA) method instead of the traditional Fourier transform. The neutral limit f e ¼ 0.8 implies that there is an imbalance between TKE production and dissipation in the simplified TKE budget equation. Similarly, we found a production-dissipation imbalance for the temperature fluctuation budget equation. Correcting for the production-dissipation imbalance, the 'standard' MOST functions for dimensionless wind speed and temperature gradients (/ m and / h ) were determined from f e and f T and compared with the / m and / h formulations of Businger and others. We found good agreement with the Beljaars and Holtslag [J. Appl. Meteorol. 30, 327-341 (1991)] relations. Lastly, the flux and gradient Richardson numbers are discussed also in terms of f e and f T .

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Section: Fluxes From E and C T 2 In Intermittent Turbulent Conditionsmentioning

confidence: 95%

Monin–Obukhov Similarity Functions of the Structure Parameter of Temperature and Turbulent Kinetic Energy Dissipation Rate in the Stable Boundary Layer

Hartogensis

Bruin

2005

Boundary-Layer Meteorol

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“…, under neutral condition, shows a large scattering because T  and * T are both varying close to zero, and consequently the experimental accuracy is expected to be very low (Pahlow et al, 2001;De Bruin and Hartogensis, 2005). Another aspect that contributes to this the larger scattering is the temperature fluctuations associated to the thermal heterogeneities, which can exist even if the H is almost zero in a mean sense (Kader and Yaglom, 1990;Tsvang et al, 1998).…”

Section: A) Standard Deviation Of Temperaturementioning

confidence: 99%

Atmospheric surface layer characteristics of turbulence above the Pantanal wetland regarding the similarity theory

Filho

Sá

Karam

et al. 2008

Agricultural and Forest Meteorology

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In this manuscript, some micrometeorological characteristics of the Pantanal are presented. This region, one of the greatest wetlands in the world, is located in the central western part of South America. It has very peculiar environmental and ecological characteristics, a great biodiversity and an irregular hydrological cycle, which often presents floods during the wet season and droughts and fires during the dry season. The experimental data were collected in a meteorological tower during the Interdisciplinary Pantanal Experiment (IPE), on April-May 1998. This was a transition period between the wet and the dry season, which a shallow water layer was present at several parts of the experimental field, even around the 25m-height meteorological tower. The surface energy budget components associated with the existence of the shallow water layer, its diurnal variability and some turbulent variables related to the surface-atmosphere turbulent exchange processes were investigated. Eddy-correlation and variance methods have been used to estimate turbulent fluxes and to study the validity of the Monin-Obukhov similarity theory for the Pantanal region. A mixed layer slab model has been used to estimate the height of the turbulent mixing-layer and to INPE ePrint: sid.inpe.br/mtc-m17@80/2007/12.17.11.41 v1 2007 provide useful information to test the validity of general relationships concerning horizontal wind velocity variances above Pantanal. In general, the dimensionless relationships between turbulent variables and scaling parameters agree well with the ones found in the literature. Some aspects regarding the heat storage in the shallow water layer present interesting information about its role in the surface-atmosphere energy exchanges processes along the day.INPE ePrint: sid.inpe.br /mtc-m17@80/2007/12.17.11.41 v1 2007-12-18 -m17@80/2007/12.17.11.41 v1 2007-12-18 Answer to the ReviewersWe want to thank to the Reviewers for the second revision. We appreciate very well the useful suggestions. The answers are enclosed below. Questions 1) I wonder if the near jump in the model for 8b) is really supported by the data?A smooth jump has been observed in the data, which could be adjusted by a sigmoidal function with a relatively small width. This type of fitting is based on the idea of that the correlation coefficients, wT r and uw r , are nearly constants along some defined intervals of  (according to Table 2 of Kaimal et al., 1972).The correlation coefficients can be viewed as a measure of the overall efficiency of the transfer and varies between zero (no correlation) and 1 (optimally efficient transfer) (Roth and Oke, 1995). In accord with these authors the relative transfer efficiencies are given by:where the universal function for the Pantanal are:To verify the sigmoidal fits, the modeled ratio INPE ePrint: sid.inpe.br/mtc-m17@80/2007/12. 17.11.41 v1 2007-12-18 To verify the fits, the modeled ratio between the new sigmoidal curves (Eqs. 2a and 2b)is compared with the observed ratio and with the...

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“…In order to accomplish the steady-state requirement for the calculation of covariances, a linear detrending routine was first applied to some of the scalar raw datasets (i.e. concentrations and temperature) (Goulden et al 1996;Rannik and Vesala 1999;Moncrieff et al 2004;De Bruin and Hartogensis 2005). As the used variables were recorded with different measurement systems, a time-lag correction was conducted to resynchronise the wind components and scalar variables if necessary, before calculating the covariances (Massman and Lee 2002;Foken 2006).…”

Section: Quality Verification Of the Eddy Covariance Datamentioning

confidence: 99%

Gap Filling and Quality Assessment of CO2 and Water Vapour Fluxes above an Urban Area with Radial Basis Function Neural Networks

Schmidt

Wrzesinsky

Klemm

2007

Boundary-Layer Meteorol

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Vertical turbulent fluxes of water vapour, carbon dioxide, and sensible heat were measured from 16 August to the 28 September 2006 near the city centre of Münster in northwest Germany. In comparison to results of measurements above homogeneous ecosystem sites, the CO 2 fluxes above the urban investigation area showed more peaks and higher variances during the course of a day, probably caused by traffic and other varying, anthropogenic sources. The main goal of this study is the introduction and establishment of a new gap filling procedure using radial basis function (RBF) neural networks, which is also applicable under complex environmental conditions. We applied adapted RBF neural networks within a combined modular expert system of neural networks as an innovative approach to fill data gaps in micrometeorological flux time series. We found that RBF networks are superior to multilayer perceptron (MLP) neural networks in the reproduction of the highly variable turbulent fluxes. In addition, we enhanced the methodology in the field of quality assessment for eddy covariance data. An RBF neural network mapping system was used to identify conditions of a turbulence regime that allows reliable quantification of turbulent fluxes through finding an acceptable minimum of the friction velocity. For the data analysed in this study, the minimum acceptable friction velocity was found to be 0.15 m s −1 . The obtained CO 2 fluxes, measured on a tower at 65 m a.g.l., reached average values of 12 µmol m −2 s −1 and fell to nighttime minimum values of 3 µmol m −2 s −1 . Mean daily CO 2 emissions of 21 g CO 2 m −2 d −1 were obtained during our 6-week experiment. Hence, the city centre of Münster appeared to be a significant source of CO 2 . The half-hourly average values of water vapour fluxes ranged between 0.062 and 0.989 mmol m −2 s −1 and showed lower variances than the simultaneously measured fluxes of CO 2 .

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Variance Method to Determine Turbulent Fluxes of Momentum And Sensible Heat in The Stable Atmospheric Surface Layer

Cited by 13 publications

References 23 publications

Monin–Obukhov Similarity Functions of the Structure Parameter of Temperature and Turbulent Kinetic Energy Dissipation Rate in the Stable Boundary Layer

Monin–Obukhov Similarity Functions of the Structure Parameter of Temperature and Turbulent Kinetic Energy Dissipation Rate in the Stable Boundary Layer

Atmospheric surface layer characteristics of turbulence above the Pantanal wetland regarding the similarity theory

Gap Filling and Quality Assessment of CO2 and Water Vapour Fluxes above an Urban Area with Radial Basis Function Neural Networks

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