Tutorial

Output variables and urban descriptors


This tutorial explains the meaning of the different variables that are stored in the output files, as well as the different urban descriptors that are calculated by LASER/F for the simulation purpose.

1) Output variables

The complete list of the output variables follows:

Direct (W/m²): direct solar radiation (incident on the surface)
Dif_Atmos (W/m²): diffuse atmospheric solar radiation (incident on the surface)
Recu_sol_solaire (W/m²): solar radiation received from the urban elements after lambertian reflection (incident on the surface)
Recu_specul_solaire (W/m²): solar radiation received from the urban elements after specular reflection (incident on the surface)
Reflechi_specul_solaire (W/m²): specular reflection of solar radiation (lost from the surface)
Reflechi_lamb_solaire (W/m²): lambertian reflection of solar radiation (lost from the surface)
Transmis_solaire (W/m²): transmitted solar radiation (for transparent objects) (lost from the surface)
Bilan_solaire (W/m²): solar radiation balance
Atmos_IR (W/m²): incident atmospheric infrared (IR) radiation (incident on the surface)
Recu_sol_IR (W/m²): infrared radiation (IR) received from other surface elements after reflection or emission (incident on the surface)
Transmis_IR (W/m²): transmitted infrared radiation (IR) (lost from the surface)
Emis_IR (W/m²): emitted infrared radiation (IR) (lost from the surface)
Reflechi_IR (W/m²): reflected infrared radiation (IR) (lost from the surface)
Bilan_IR (W/m²): infrared radiation (IR) radiation balance
RN (W/m²): net radiation, radiation balance
Sensible (W/m²): sensible heat flux, positive upward
Latent (W/m²): total latent heat flux (evaporation + transpiration), positive upward
ETR (W/m²): transpiration heat flux from vegetation only, positive upward
Ground (W/m²): ground heat flux, positive downward
Stock (W/m²): stock variation of the surface half-layer: positive = warming; negative =cooling
Anthro_S (W/m²): sensible anthropogenic heat flux (buildings or roads)
Anthro_L (W/m²): latent anthropogenic heat flux (buildings or roads)
Emissivite (-): emissivity
Ref_dir_Lamb (-): reflection coefficient for direct solar radiation
Ref_dif_Lamb (-): reflection coefficient for diffuse solar radiation
WR (kg/m²): water reservoir at the surface
Resa (s/m): aerodynamic resistance
Aerocond (m/s): aerodynamic conductivity
LAI (-): Leaf Area Index for vegetation
GreenVegFraction (-): active vegetation fraction
Alb_veg (-): reflection coefficient for solar radiation of the vegetation
Alb_Soil (-): reflection coefficient for solar radiation of natural soil
Z0 (m): rugosity
Qs (kg/kg): specific humidity at the surface
SkyView (-): skyview factor
Ts (C): Surface temperature
WGs (m3/m3): volumetric water content of the first soil layer
WGIs (m3/m3): volumetric ice content of the first soil layer
TMRT (C): Mean Radiant Temperature at the surface of the ground
UTCI (C): Thermal UTCI confomfort index at the surface of the ground
V_can (m/s): wind speed at mid-level of the urban canopy
Ustar_can (m/s): Ustar at mid level of the urban canopy
T_can (C): air temperature at mid level of the urban canopy
Q_can_kg (kg/kg): specific air humidity at mid level of the urban canopy
HR_can (-): relative humidity at mid level of the urban canopy
Va (m/s): atmospheric wind speed prescribed over the above level (forcing file)
Ta (C): atmospheric temperature prescribed over the above level (forcing file)
Qa (kg/kg): atmospheric specific humidity prescribed above the roof level (forcing file)
HRa (-): atmospheric relative humidity prescribed above the roof level (forcing file)
Ps (Pa): atmospheric pressure at sea level (forcing file)
Rho (kg/m3): air density
Pliquide (kg/m²/s): liquid precipitation (forcing file)
Psolide (kg/m²/s): solid precipitation: snow (forcing file)
Forçage direct solaire horizontal (W/m²): direct horizontal solar radiation above the roof level (forcing file)
Forçage diffus solaire horizontal (W/m²): diffuse solar radiation above the roof level (forcing file)
Forçage IR atmosphérique (W/m²): IR atmospheric radiation above the roof level (forcing file)

2) Urban descriptors