Evaluation of Two Energy Balance Closure Parametrizations

Eder, Fabian; Roo, Frederik De; Kohnert, Katrin; Desjardins, Raymond L.; Schmid, Hans‐Peter; Mauder, Matthias

doi:10.1007/s10546-013-9904-0

Cited by 40 publications

(35 citation statements)

References 80 publications

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“…Such nonlinear effects, that control both evaporative fluxes and energy partitioning with surface drying (Aminzadeh and Or, 2013), clearly affect energy balance closure of atmospheric-based measurements Foken, 2008;Leuning et al, 2012;Wohlfahrt and Widmoser, 2013;Eder et al, 2014).…”

Section: Laminar Turbulentmentioning

confidence: 99%

Linking evaporative fluxes from bare soil across surface viscous sublayer with the Monin–Obukhov atmospheric flux-profile estimates

Haghighi

2015

Journal of Hydrology

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Section: Laminar Turbulentmentioning

confidence: 99%

Linking evaporative fluxes from bare soil across surface viscous sublayer with the Monin–Obukhov atmospheric flux-profile estimates

Haghighi

2015

Journal of Hydrology

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“…Strong differences in surface properties and large swaths of such surface patches are known to induce secondary circulations (Mahfouf et al, 1987;Dalu and Pielke, 1993;Raupach and Finnigan, 1995;Courault et al, 2007;van Heerwaarden and Guerau de Arellano, 2008;Garcia-Carreras et al, 2010;Banerjee et al, 2013;Dixon et al, 2013;Sühring and Raasch, 2013;Kang and Lenschow, 2014;Van Heerwaarden et al, 2014). Recent works by Mauder et al (2007), Stoy et al (2013) and Eder et al (2014) have suggested that non-closure of the energy balance is also related to advection and flux divergence due to secondary circulations (Kanda et al, 2004;Foken, 2008). The non-closure of the energy balance refers to the fact that the available energy R n − G is often higher than the turbulent energy H + LE at micrometeorological sites, where R n is net radiation, G is soil heat flux, H is sensible heat flux and LE is latent heat flux.…”

Section: Introductionmentioning

confidence: 97%

Turbulent transport of energy across a forest and a semiarid shrubland

et al. 2018

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Abstract. The role of secondary circulations has recently been studied in the context of well-defined surface heterogeneity in a semiarid ecosystem where it was found that energy balance closure over a desert-forest system and the structure of the boundary layer was impacted by advection and flux divergence. As a part of the CliFF ("Climate feedbacks and benefits of semi-arid forests", a collaboration between KIT, Germany, and the Weizmann Institute, Israel) campaign, we studied the boundary layer dynamics and turbulent transport of energy corresponding to this effect in Yatir Forest situated in the Negev Desert in Israel. The forest surrounded by small shrubs presents a distinct feature of surface heterogeneity, allowing us to study the differences between their interactions with the atmosphere above by conducting measurements with two eddy covariance (EC) stations and two Doppler lidars. As expected, the turbulence intensity and vertical fluxes of momentum and sensible heat are found to be higher above the forest compared to the shrubland. Turbulent statistics indicative of nonlocal motions are also found to differ over the forest and shrubland and also display a strong diurnal cycle. The production of turbulent kinetic energy (TKE) over the forest is strongly mechanical, while buoyancy effects generate most of the TKE over the shrubland. Overall TKE production is much higher above the forest compared to the shrubland. The forest is also found to be more efficient in dissipating TKE. The TKE budget appears to be balanced on average both for the forest and shrubland, although the imbalance of the TKE budget, which includes the role of TKE transport, is found to be quite different in terms of diurnal cycles for the forest and shrubland. The difference in turbulent quantities and the relationships between the components of TKE budget are used to infer the characteristics of the turbulent transport of energy between the desert and the forest.

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“…In a first approximation, the heterogeneity of the landscape around a measurement site can be characterized by the dominant length scale of a suitable surface variable. In Eder et al (2014), the dominant length scales corresponding to a few sites belonging to the TERENO measurement network (Zacharias et al, 2011) were computed from the Fourier spectrum of the surface roughness. The site with the least pronounced topography, the site Fendt, has an effective length scale close to 3 km and a mean EBR of 0.77, which is a typical value for the energy balance ratio (Stoy et al, 2013).…”

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confidence: 99%

The influence of idealized surface heterogeneity on virtual turbulent flux measurements

Roo

Mauder

2018

Atmos. Chem. Phys.

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Abstract. The imbalance of the surface energy budget in eddy-covariance measurements is still an unsolved problem. A possible cause is the presence of land surface heterogeneity, which affects the boundary-layer turbulence. To investigate the impact of surface variables on the partitioning of the energy budget of flux measurements in the surface layer under convective conditions, we set up a systematic parameter study by means of large-eddy simulation. For the study we use a virtual control volume approach, which allows the determination of advection by the mean flow, flux-divergence and storage terms of the energy budget at the virtual measurement site, in addition to the standard turbulent flux. We focus on the heterogeneity of the surface fluxes and keep the topography flat. The surface fluxes vary locally in intensity and these patches have different length scales. Intensity and length scales can vary for the two horizontal dimensions but follow an idealized chessboard pattern. Our main focus lies on surface heterogeneity of the kilometer scale, and one order of magnitude smaller. For these two length scales, we investigate the average response of the fluxes at a number of virtual towers, when varying the heterogeneity length within the length scale and when varying the contrast between the different patches. For each simulation, virtual measurement towers were positioned at functionally different positions (e.g., downdraft region, updraft region, at border between domains, etc.). As the storage term is always small, the non-closure is given by the sum of the advection by the mean flow and the flux-divergence. Remarkably, the missing flux can be described by either the advection by the mean flow or the flux-divergence separately, because the latter two have a high correlation with each other. For kilometer scale heterogeneity, we notice a clear dependence of the updrafts and downdrafts on the surface heterogeneity and likewise we also see a dependence of the energy partitioning on the tower location. For the hectometer scale, we do not notice such a clear dependence. Finally, we seek correlators for the energy balance ratio in the simulations. The correlation with the friction velocity is less pronounced than previously found, but this is likely due to our concentration on effectively strongly to freely convective conditions.

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Evaluation of Two Energy Balance Closure Parametrizations

Cited by 40 publications

References 80 publications

Linking evaporative fluxes from bare soil across surface viscous sublayer with the Monin–Obukhov atmospheric flux-profile estimates

Linking evaporative fluxes from bare soil across surface viscous sublayer with the Monin–Obukhov atmospheric flux-profile estimates

Turbulent transport of energy across a forest and a semiarid shrubland

The influence of idealized surface heterogeneity on virtual turbulent flux measurements

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