scholarly journals An urban trees parameterization for modeling microclimatic variables and thermal comfort conditions at street level with the Town Energy Balance model (TEB-SURFEX v8.0)

2020 ◽  
Vol 13 (2) ◽  
pp. 385-399 ◽  
Author(s):  
Emilie Redon ◽  
Aude Lemonsu ◽  
Valéry Masson
Keyword(s):  
Energy Balance ◽  
Wind Speed ◽  
Air Temperature ◽  
Urban Canopy ◽  
Turbulent Fluxes ◽  
Urban Trees ◽  
Radiation Absorption ◽  
Balance Model ◽  
Climate Index ◽  
The Town

Abstract. The Town Energy Balance (TEB) urban climate model has recently been improved to more realistically address the radiative effects of trees within the urban canopy. These processes necessarily have an impact on the energy balance that needs to be taken into account. This is why a new method for calculating the turbulent fluxes for sensible and latent heat has been implemented. This method remains consistent with the “bigleaf” approach of the Interaction Soil–Biosphere–Atmosphere (ISBA) model, which deals with energy exchanges between vegetation and atmosphere within TEB. Nonetheless, the turbulent fluxes can now be dissociated between ground-based natural covers and the tree stratum above (knowing the vertical leaf density profile), which can modify the vertical profile in air temperature and humidity in the urban canopy. In addition, the aeraulic effect of trees is added, parameterized as a drag term and an energy dissipation term in the evolution equations of momentum and turbulent kinetic energy, respectively. This set of modifications relating to the explicit representation of the tree stratum in TEB is evaluated on an experimental case study. The model results are compared to micrometeorological and surface temperature measurements collected in a semi-open courtyard with trees and bordered by buildings. The new parameterizations improve the modeling of surface temperatures of walls and pavements, thanks to taking into account radiation absorption by trees, and of air temperature. The effect of wind speed being strongly slowed down by trees is also much more realistic. The universal thermal climate index diagnosed in TEB from inside-canyon environmental variables is highly dependent and sensitive to these variations in wind speed and radiation. This demonstrates the importance of properly modeling interactions between buildings and trees in urban environments, especially for climate-sensitive design issues.

scholarly journals An urban trees parameterization for modelling microclimatic variables and thermal comfort conditions at street level with the Town Energy Balance model (TEB-SURFEX v8.0)

2019 ◽  
Author(s):  
Emilie Redon ◽  
Aude Lemonsu ◽  
Valéry Masson
Keyword(s):  
Energy Balance ◽  
Wind Speed ◽  
Air Temperature ◽  
Evolution Equations ◽  
Urban Canopy ◽  
Turbulent Fluxes ◽  
Urban Trees ◽  
Radiation Absorption ◽  
Balance Model ◽  
Climate Index

Abstract. The TEB urban climate model has recently been improved to more realistically address the radiative effects of trees within the urban canopy. These processes necessarily have an impact on the energy balance that needs to be taken into account. This is why a new method for calculating the turbulent fluxes for sensible and latent heat has been implemented. This method remains consistent with the "bigleaf" approach of the ISBA model which deals with energy exchanges between vegetation and atmosphere within TEB. Nonetheless, the turbulent fluxes can now be dissociated between ground-based natural covers and tree stratum above (knowing the vertical leaf density profile), which can modify the vertical profile in air temperature and humidity in the urban canopy. In addition, the aeraulic effect of trees is added, parameterized as a drag term and an energy dissipation term in the evolution equations of momentum and of turbulent kinetic energy, respectively. This set of modifications relating to the explicit representation of tree stratum in TEB is evaluated on an experimental case study. The model results are compared to micrometeorological and surface temperature measurements collected in a semi-open courtyard with trees and bordered by buildings. The new parameterizations improve the modelling of surface temperatures of walls and pavements thanks to taking into account radiation absorption by trees, and of air temperature. The wind speed is strongly slowed down by trees that is also much more realistic. The universal thermal climate index diagnosed in TEB from inside-canyon environmental variables is highly dependent and sensitive to these variations in wind speed and radiation. This demonstrates the importance of properly modelling interactions between buildings and trees in urban environments, especially for climate-sensitive design issues.

Snowmelt modeling in a balsam fir forest: comparison between an energy balance model and other simplified models

1991 ◽  
Vol 21 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Marcel Prévost ◽  
Richard Barry ◽  
Jean Stein ◽  
André P. Plamondon
Keyword(s):  
Energy Balance ◽  
Snow Cover ◽  
Air Temperature ◽  
Meteorological Parameters ◽  
Daily Basis ◽  
Energy Balance Model ◽  
Balsam Fir ◽  
Radiation Absorption ◽  
Balance Model ◽  
Wave Radiation

This study compares snowmelt models and determines the relative importance of the meteorological parameters affecting snowmelt during the 1985, 1986, and 1987 melt seasons in a dense balsam fir stand in Laurentide forest, 80 km north of the city of Québec. Net all-wave radiation, air temperature, wind speed, relative humidity, and rainfall were correlated with meltwater that reached the base of the snow cover as measured with a 20-m2 snow lysimeter. The estimation of energy balance components of the snow cover during the snowmelt period showed that while solar radiation absorption dominated, turbulent transfers as well as heat exchanges with ground and rain were negligible. The temperature index model SNOW-17 yielded predictions of snow cover outflow as accurately as the energy balance model, both explaining 64% of hourly outflow variation and more than 85% of daily outflow variation. Single meteorological parameters usually explained less than 25% of the hourly melt because of the meltwater transmission lag through the snowpack. On a daily basis, the relationships using air temperature or net all-wave radiation as sole index both explained nearly 70% of snowmelt outflow for the same period. Combining these two parameters with rainfall in the same equation increased the explained variance to 85%.

scholarly journals Inclusion of vegetation in the Town Energy Balance model for modelling urban green areas

2012 ◽  
Vol 5 (6) ◽  
pp. 1377-1393 ◽  
Author(s):  
A. Lemonsu ◽  
V. Masson ◽  
L. Shashua-Bar ◽  
E. Erell ◽  
D. Pearlmutter
Keyword(s):  
Energy Balance ◽  
Global Climate ◽  
A Priori ◽  
Urban Canopy ◽  
Bare Soil ◽  
Urban Heat Islands ◽  
Balance Model ◽  
Local Climate ◽  
The Impact ◽  
The Town

Abstract. Cities impact both local climate, through urban heat islands and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representation into urban models will allow us to address more accurately these questions. This paper presents an improvement of the Town Energy Balance (TEB) urban canopy model. Vegetation is directly included inside the canyon, allowing shadowing of grass by buildings, better representation of urban canopy form and, a priori, a more accurate simulation of canyon air microclimate. The surface exchanges over vegetation are modelled with the well-known Interaction Soil Biosphere Atmosphere (ISBA) model that is integrated in the TEB's code architecture in order to account for interactions between natural and built-up covers. The design of the code makes possible to plug and use any vegetation scheme. Both versions of TEB are confronted to experimental data issued from a field campaign conducted in Israel in 2007. Two semi-enclosed courtyards arranged with bare soil or watered lawn were instrumented to evaluate the impact of landscaping strategies on microclimatic variables and evapotranspiration. For this case study, the new version of the model with integrated vegetation performs better than if vegetation is treated outside the canyon. Surface temperatures are closer to the observations, especially at night when radiative trapping is important. The integrated vegetation version simulates a more humid air inside the canyon. The microclimatic quantities (i.e., the street-level meteorological variables) are better simulated with this new version. This opens opportunities to study with better accuracy the urban microclimate, down to the micro (or canyon) scale.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

scholarly journals Modeling Shoot-tip Temperature in the Greenhouse Environment

1998 ◽  
Vol 123 (2) ◽  
pp. 208-214 ◽  
Author(s):  
James E. Faust ◽  
Royal D. Heins
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Air Temperature ◽  
Flower Development ◽  
Vapor Pressure Deficit ◽  
Shoot Tip ◽  
Balance Model ◽  
Glass Temperature ◽  
Air Temperatures ◽  
Material Temperature

An energy-balance model is described that predicts vinca (Catharanthus roseus L.) shoot-tip temperature using four environmental measurements: solar radiation and dry bulb, wet bulb, and glazing material temperature. The time and magnitude of the differences between shoot-tip and air temperature were determined in greenhouses maintained at air temperatures of 15, 20, 25, 30, or 35 °C. At night, shoot-tip temperature was always below air temperature. Shoot-tip temperature decreased from 0.5 to 5 °C below air temperature as greenhouse glass temperature decreased from 2 to 15 °C below air temperature. During the photoperiod under low vapor-pressure deficit (VPD) and low air temperature, shoot-tip temperature increased ≈4 °C as solar radiation increased from 0 to 600 W·m-2. Under high VPD and high air temperature, shoot-tip temperature initially decreased 1 to 2 °C at sunrise, then increased later in the morning as solar radiation increased. The model predicted shoot-tip temperatures within ±1 °C of 81% of the observed 1-hour average shoot-tip temperatures. The model was used to simulate shoot-tip temperatures under different VPD, solar radiation, and air temperatures. Since the rate of leaf and flower development are influenced by the temperature of the meristematic tissues, a model of shoot-tip temperature will be a valuable tool to predict plant development in greenhouses and to control the greenhouse environment based on a plant temperature setpoint.

scholarly journals Response of the Energy Balance on the Margin of the Greenland Ice Sheet to Temperature Changes

1990 ◽  
Vol 36 (123) ◽  
pp. 217-221 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Ole B. Olesen
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Temperature Response ◽  
Greenland Ice Sheet ◽  
Energy Balance Model ◽  
Balance Model ◽  
Sensible Heat

AbstractDaily ice ablation on two outlet glaciers from the Greenland ice sheet, Nordbogletscher (1979–83) and Qamanârssûp sermia (1980–86), is related to air temperature by a linear regression equation. Analysis of this ablation-temperature equation with the help of a simple energy-balance model shows that sensible-heat flux has the greatest temperature response and accounts for about one-half of the temperature response of ablation. Net radiation accounts for about one-quarter of the temperature response of ablation, and latent-heat flux and errors account for the remainder. The temperature response of sensible-heat flux at QQamanârssûp sermia is greater than at Nordbogletscher mainly due to higher average wind speeds. The association of high winds with high temperatures during Föhn events further increases sensible-heat flux. The energy-balance model shows that ablation from a snow surface is only about half that from an ice surface at the same air temperature.

scholarly journals Improvements to the hydrological processes of the Town Energy Balance model (TEB-Veg, SURFEX v7.3) for urban modelling and impact assessment

2018 ◽  
Vol 11 (10) ◽  
pp. 4175-4194 ◽  
Author(s):  
Xenia Stavropulos-Laffaille ◽  
Katia Chancibault ◽  
Jean-Marc Brun ◽  
Aude Lemonsu ◽  
Valéry Masson ◽  
...  
Keyword(s):  
Energy Balance ◽  
High Performance ◽  
Hydrological Processes ◽  
Balance Model ◽  
Statistical Criterion ◽  
Model Parameters ◽  
Water Drainage ◽  
Deep Drainage ◽  
Complete Representation ◽  
The Town

Abstract. Climate change and demographic pressures are affecting both the urban water balance and microclimate, thus amplifying urban flooding and the urban heat island phenomena. These issues need to be addressed when engaging in urban planning activities. Local authorities and stakeholders have therefore opted for more nature-based adaptation strategies, which are especially suitable in influencing hydrological and energy processes. Assessing the multiple benefits of such strategies on the urban microclimate requires high-performance numerical tools. This paper presents recent developments dedicated to the water budget in the Town Energy Balance for vegetated surfaces (TEB-Veg) model (surface externalisée; SURFEX v7.3), thus providing a more complete representation of the hydrological processes taking place in the urban subsoil. This new hydrological module is called TEB-Hydro. Its inherent features include the introduction of subsoil beneath built surfaces, the horizontal rebalancing of intra-mesh soil moisture, soil water drainage via the sewer network and the limitation of deep drainage. A sensitivity analysis is then performed in order to identify the hydrological parameters required for model calibration. This new TEB-Hydro model is evaluated on two small residential catchments in Nantes (France), over two distinct periods, by comparing simulated sewer discharge with observed findings. In both cases, the model tends to overestimate total sewer discharge and performs better under wet weather conditions, with a Kling–Gupta efficiency (KGE) statistical criterion greater than 0.80 vs. approximately 0.60 under drier conditions. These results are encouraging since the same set of model parameters is identified for both catchments, irrespective of meteorological and local physical conditions. This approach offers opportunities to apply the TEB-Hydro model at the city scale alongside projections of climate and demographic changes.

scholarly journals Surface turbulent fluxes over pack ice inferred from TOVS observations

1997 ◽  
Vol 25 ◽  
pp. 393-399
Author(s):  
R.W. Lindsay ◽  
J. A. Francis ◽  
P. O. G. Persson ◽  
D. A. Roterock ◽  
A.J. Schweiger
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Air Temperature ◽  
Sensible Heat Flux ◽  
Turbulent Fluxes ◽  
Layer Model ◽  
Radiative Fluxes ◽  
Mean Values ◽  
Boundary Layer Model ◽  
Meteorological Observations

A one-dimensional, atmospheric boundary-layer model is coupled to a thermodynamic ice model to estimate the surface turbulent fluxes over thick sea ice. The principal forcing parameters in this time-dependent model are the air temperature, humidity, and wind speed at a specified level (either at 2 m or at 850 mb) and the down-welling surface radiative fluxes, The free parameters are the air temperature, humidity, and wind-speed profiles below the specified level, the surface skin temperature and ice-temperature profile, and the surface turbulent fluxes. The goal is to determine how well we can estimate the turbulent surface heat and momentum fluxes using forcing parameters from atmospheric temperatures and radiative fluxes retrieved Irom the TlROS-N Operational Vertical Sounder TOVS) data.Meteorological observations from the Lead Experiment (LeadEx, April 1992) ice camp are used to validate turbulent fluxes computed with the surface observations, and the results are used to compare with estimates based on radiosonde observations or with estimates based on TOVS data. We and that the TOVS-based estimates of the stress are significantly more accurate than those found with a constant geostrophic drag coefficient, with a rool mean square error about half as large. This improvement is due to stratification effects included in the boundary-layer model. The errors in the sensible heat flux estimates, however, are large compared Io the small mean values observed during the field experiment.

scholarly journals Evaluation of the Town Energy Balance Model in Cold and Snowy Conditions during the Montreal Urban Snow Experiment 2005

2010 ◽  
Vol 49 (3) ◽  
pp. 346-362 ◽  
Author(s):  
A. Lemonsu ◽  
S. Bélair ◽  
J. Mailhot ◽  
S. Leroyer
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Transition Period ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Anthropogenic Heat ◽  
Balance Model ◽  
Spatial And Temporal Variability ◽  
The Town

Abstract Using the Montreal Urban Snow Experiment (MUSE) 2005 database, surface radiation and energy exchanges are simulated in offline mode with the Town Energy Balance (TEB) and the Interactions between Soil, Biosphere, and Atmosphere (ISBA) parameterizations over a heavily populated residential area of Montreal, Quebec, Canada, during the winter–spring transition period (from March to April 2005). The comparison of simulations with flux measurements indicates that the system performs well when roads and alleys are snow covered. In contrast, the storage heat flux is largely underestimated in favor of the sensible heat flux at the end of the period when snow is melted. An evaluation and an improvement of TEB’s snow parameterization have also been conducted by using snow property measurements taken during intensive observational periods. Snow density, depth, and albedo are correctly simulated by TEB for alleys where snow cover is relatively homogeneous. Results are not as good for the evolution of snow on roads, which is more challenging because of spatial and temporal variability related to human activity. An analysis of the residual term of the energy budget—including contributions of snowmelt, heat storage, and anthropogenic heat—is performed by using modeling results and observations. It is found that snowmelt and anthropogenic heat fluxes are reasonably well represented by TEB–ISBA, whereas storage heat flux is underestimated.

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