A semi-empirical model of the energy balance closure in the surface layer.

It has been hypothesized that the energy balance closure problem of single-tower eddy-covariance measurements is linked to large-scale turbulent transport. In order to shed light on this problem, we investigate the functional dependence of the normalized residual for the potential temperature and hu...

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Main Authors: Frederik De Roo, Sha Zhang, Sadiq Huq, Matthias Mauder
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2018-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0209022
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spelling doaj-e76a426dab804e39a04e633a4b6601752021-03-03T21:03:00ZengPublic Library of Science (PLoS)PLoS ONE1932-62032018-01-011312e020902210.1371/journal.pone.0209022A semi-empirical model of the energy balance closure in the surface layer.Frederik De RooSha ZhangSadiq HuqMatthias MauderIt has been hypothesized that the energy balance closure problem of single-tower eddy-covariance measurements is linked to large-scale turbulent transport. In order to shed light on this problem, we investigate the functional dependence of the normalized residual for the potential temperature and humidity conservation equations, i.e. the imbalance ratio for the fluxes of latent and sensible heat. We set up a suite of simulations consisting of cases with different stability and surface Bowen ratio. We employ a nesting approach in the lower part of the atmospheric boundary-layer to achieve higher spatial resolution near the surface. Our simulations reproduce earlier simulation results for the mixed layer and also mimic the saw-blade pattern of real flux measurements. Focusing on homogeneous terrain, we derive a parameterization for the spatially averaged flux imbalance ratios of latent and sensible heat in the surface layer. We also investigate how the remaining imbalance for a given point measurement is related to the local turbulence, by deriving a statistical model based on turbulence characteristics that are related to large-scale turbulence. The average imbalance ratio scales well with friction velocity, especially for sensible heat. For the latent heat flux, our results show that the Bowen ratio also influences the underestimation. Furthermore, in the surface layer the residual has a linear dependence on the absolute height divided by the boundary-layer height. Our parameterization allows us to deduce an expression for the residual in the energy budget for a particular measurement half hour, based on the measurement height and stability.https://doi.org/10.1371/journal.pone.0209022
collection DOAJ
language English
format Article
sources DOAJ
author Frederik De Roo
Sha Zhang
Sadiq Huq
Matthias Mauder
spellingShingle Frederik De Roo
Sha Zhang
Sadiq Huq
Matthias Mauder
A semi-empirical model of the energy balance closure in the surface layer.
PLoS ONE
author_facet Frederik De Roo
Sha Zhang
Sadiq Huq
Matthias Mauder
author_sort Frederik De Roo
title A semi-empirical model of the energy balance closure in the surface layer.
title_short A semi-empirical model of the energy balance closure in the surface layer.
title_full A semi-empirical model of the energy balance closure in the surface layer.
title_fullStr A semi-empirical model of the energy balance closure in the surface layer.
title_full_unstemmed A semi-empirical model of the energy balance closure in the surface layer.
title_sort semi-empirical model of the energy balance closure in the surface layer.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2018-01-01
description It has been hypothesized that the energy balance closure problem of single-tower eddy-covariance measurements is linked to large-scale turbulent transport. In order to shed light on this problem, we investigate the functional dependence of the normalized residual for the potential temperature and humidity conservation equations, i.e. the imbalance ratio for the fluxes of latent and sensible heat. We set up a suite of simulations consisting of cases with different stability and surface Bowen ratio. We employ a nesting approach in the lower part of the atmospheric boundary-layer to achieve higher spatial resolution near the surface. Our simulations reproduce earlier simulation results for the mixed layer and also mimic the saw-blade pattern of real flux measurements. Focusing on homogeneous terrain, we derive a parameterization for the spatially averaged flux imbalance ratios of latent and sensible heat in the surface layer. We also investigate how the remaining imbalance for a given point measurement is related to the local turbulence, by deriving a statistical model based on turbulence characteristics that are related to large-scale turbulence. The average imbalance ratio scales well with friction velocity, especially for sensible heat. For the latent heat flux, our results show that the Bowen ratio also influences the underestimation. Furthermore, in the surface layer the residual has a linear dependence on the absolute height divided by the boundary-layer height. Our parameterization allows us to deduce an expression for the residual in the energy budget for a particular measurement half hour, based on the measurement height and stability.
url https://doi.org/10.1371/journal.pone.0209022
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