PET formulas (Heat Overlay): Difference between revisions
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* <math>T_{a,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Atmospheric_Temperature_formula |atmospheric temperature]] at time t; | * <math>T_{a,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Atmospheric_Temperature_formula |atmospheric temperature]] at time t; | ||
* <math>Q_{gl,t}</math> is the [[Hourly_radiation_(Heat_Overlay)|hourly radiation]] at time t; | * <math>Q_{gl,t}</math> is the [[Hourly_radiation_(Heat_Overlay)|hourly radiation]] at time t; | ||
* <math>u_{t}</math> is the calculated [[ | * <math>u_{t}</math> is the calculated [[Wind_calculation_model_(Heat_Overlay)|wind speed]] at 1.2 meters above ground time t; | ||
* <math>T_{w,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Wet-bulb_Temperature_formula | wet-bulb temperature]] at time t; | * <math>T_{w,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Wet-bulb_Temperature_formula | wet-bulb temperature]] at time t; | ||
* <math>\phi_{t}</math> is the [[Sun_altitude_(Heat_Overlay)|sun altitude]] at time t; | * <math>\phi_{t}</math> is the [[Sun_altitude_(Heat_Overlay)|sun altitude]] at time t; | ||
* <math>B_{b,t}</math> is the [[Bowen_ratio_(Heat_Overlay)|bowen ratio]] at time t; | * <math>B_{b,t}</math> is the [[Bowen_ratio_(Heat_Overlay)|bowen ratio]] at time t; | ||
* <math>S_{vf}</math> is the calculated [[Sky_view_factor_calculation_model_(Heat_Overlay)|sky view factor]]. | * <math>S_{vf}</math> is the calculated [[Sky_view_factor_calculation_model_(Heat_Overlay)|sky view factor]]. | ||
* Constant values are sourced from the {{Heat DPRA Report}}; | |||
==PET Shade and Night formula== | ==PET Shade and Night formula== | ||
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where, | where, | ||
* <math>T_{a,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Atmospheric_Temperature_formula |atmospheric temperature]] at time t; | * <math>T_{a,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Atmospheric_Temperature_formula |atmospheric temperature]] at time t; | ||
* <math>u_{t}</math> is the calculated [[ | * <math>u_{t}</math> is the calculated [[Wind_calculation_model_(Heat_Overlay)|wind speed]] at 1.2 meters above ground time t; | ||
* <math>T_{w,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Wet-bulb_Temperature_formula | wet-bulb temperature]] at time t; | * <math>T_{w,t}</math> is the calculated [[Temperature_formulas_(Heat_Overlay)#Wet-bulb_Temperature_formula | wet-bulb temperature]] at time t; | ||
* <math>S_{v,f}</math> is the calculated [[Sky_view_factor_calculation_model_(Heat_Overlay)|sky view factor]]; | * <math>S_{v,f}</math> is the calculated [[Sky_view_factor_calculation_model_(Heat_Overlay)|sky view factor]]; | ||
* <math>Q_{d,t}</math> is the calculated [[Diffuse_radiation_formula_(Heat_Overlay)|diffusive radiation]] at time t; | * <math>Q_{d,t}</math> is the calculated [[Diffuse_radiation_formula_(Heat_Overlay)|diffusive radiation]] at time t; | ||
* <math>\sigma</math> is the Stefan Boltzmann constant, which is <math>5.670374419...\times 10^{-8} W \cdot m^{-2} \cdot K^{-4}</math>. | * <math>\sigma</math> is the Stefan Boltzmann constant, which is <math>5.670374419...\times 10^{-8} W \cdot m^{-2} \cdot K^{-4}</math>. | ||
* Constant values are sourced from the {{Heat DPRA Report}}; | |||
{{Template:HeatOverlay_formula_nav}} | {{Template:HeatOverlay_formula_nav}} | ||
Latest revision as of 11:52, 13 September 2021
The physiological equivalent temperature PET is calculated for two possible options based on the situation:
- A cell is in the shade or it is night at time t: PETshade, night;
- A cell is in the sun during the day: PETsun;
PET Sun formula
The PET sun formula is as followed:
where,
- is the calculated atmospheric temperature at time t;
- is the hourly radiation at time t;
- is the calculated wind speed at 1.2 meters above ground time t;
- is the calculated wet-bulb temperature at time t;
- is the sun altitude at time t;
- is the bowen ratio at time t;
- is the calculated sky view factor.
- Constant values are sourced from the DPRA Heat stress report;
PET Shade and Night formula
The PET shade and night formula is as followed:
where,
- is the calculated atmospheric temperature at time t;
- is the calculated wind speed at 1.2 meters above ground time t;
- is the calculated wet-bulb temperature at time t;
- is the calculated sky view factor;
- is the calculated diffusive radiation at time t;
- is the Stefan Boltzmann constant, which is .
- Constant values are sourced from the DPRA Heat stress report;
