PET formulas (Heat Overlay): Difference between revisions
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==PET Sun formula== | ==PET Sun formula== | ||
The PET sun formula is as followed:<br> | |||
PET<sub>sun</sub> = -13.26 + 1.25 · T<sub>a,t</sub> + 0.011 · Q<sub>gl,t</sub> - 3.37 · ln(u<sub>t</sub>) + 0.078 · T<sub>w,t</sub> + 0.0055 · Q<sub>gl,t</sub> · ln(u) + 5.56 · sin(ϕ<sub>t</sub>) - 0.0103 · Q<sub>gl,t</sub> · ln(u) · sin(ϕ<sub>t</sub>) + 0.546 · B<sub>b,t</sub> + 1.94 · S<sub>vf</sub><br> | |||
where, | |||
* T<sub>a,t</sub> is the calculated [[Temperature_formulas_(Heat_Overlay)#Atmospheric_Temperature_formula |atmospheric temperature]] at time t; | |||
* Q<sub>gl,t</sub> is the [[Hourly_radiation_(Heat_Overlay)|hourly radiation]] at time t; | |||
* u<sub>t</sub> is the calculated [[Wind_speed_formula_(Heat_Overlay)|wind speed]] at 1.2m above ground time t; | |||
* T<sub>w,t</sub> is the calculated [[Temperature_formulas_(Heat_Overlay)#Wet-bulb_Temperature_formula | wet-bulb temperature]] at time t; | |||
* Q<sub>gl,t</sub> is the [[Hourly_radiation_(Heat_Overlay)|hourly radiation]] at time t; | |||
* ϕ<sub>t</sub> is the [[Sun_altitude_(Heat_Overlay)|sun altitude]] at time t; | |||
* B<sub>b,t</sub> is the [[Bowen_ratio_(Heat_Overlay)|bowen ratio]] at time t; | |||
* S<sub>vf</sub> is the calculated [[Sky_view_factor_formula_(Heat_Overlay)|sky view factor]]; | |||
==PET Shade and Night formula== | |||
The PET sun formula is as followed:<br> | The PET sun formula is as followed:<br> | ||
PET<sub>sun</sub> = -13.26 + 1.25 · T<sub>a,t</sub> + 0.011 · Q<sub>gl,t</sub> - 3.37 · ln(u<sub>t</sub>) + 0.078 · T<sub>w,t</sub> + 0.0055 · Q<sub>gl,t</sub> · ln(u) + 5.56 · sin(ϕ<sub>t</sub>) - 0.0103 · Q<sub>gl,t</sub> · ln(u) · sin(ϕ<sub>t</sub>) + 0.546 · B<sub>b,t</sub> + 1.94 · S<sub>vf</sub><br> | PET<sub>sun</sub> = -13.26 + 1.25 · T<sub>a,t</sub> + 0.011 · Q<sub>gl,t</sub> - 3.37 · ln(u<sub>t</sub>) + 0.078 · T<sub>w,t</sub> + 0.0055 · Q<sub>gl,t</sub> · ln(u) + 5.56 · sin(ϕ<sub>t</sub>) - 0.0103 · Q<sub>gl,t</sub> · ln(u) · sin(ϕ<sub>t</sub>) + 0.546 · B<sub>b,t</sub> + 1.94 · S<sub>vf</sub><br> | ||
Revision as of 11:51, 12 September 2019
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:
PETsun = -13.26 + 1.25 · Ta,t + 0.011 · Qgl,t - 3.37 · ln(ut) + 0.078 · Tw,t + 0.0055 · Qgl,t · ln(u) + 5.56 · sin(ϕt) - 0.0103 · Qgl,t · ln(u) · sin(ϕt) + 0.546 · Bb,t + 1.94 · Svf
where,
- Ta,t is the calculated atmospheric temperature at time t;
- Qgl,t is the hourly radiation at time t;
- ut is the calculated wind speed at 1.2m above ground time t;
- Tw,t is the calculated wet-bulb temperature at time t;
- Qgl,t is the hourly radiation at time t;
- ϕt is the sun altitude at time t;
- Bb,t is the bowen ratio at time t;
- Svf is the calculated sky view factor;
PET Shade and Night formula
The PET sun formula is as followed:
PETsun = -13.26 + 1.25 · Ta,t + 0.011 · Qgl,t - 3.37 · ln(ut) + 0.078 · Tw,t + 0.0055 · Qgl,t · ln(u) + 5.56 · sin(ϕt) - 0.0103 · Qgl,t · ln(u) · sin(ϕt) + 0.546 · Bb,t + 1.94 · Svf
where,
- Ta,t is the calculated atmospheric temperature at time t;
- Qgl,t is the hourly radiation at time t;
- ut is the calculated wind speed at 1.2m above ground time t;
- Tw,t is the calculated wet-bulb temperature at time t;
- Qgl,t is the hourly radiation at time t;
- ϕt is the sun altitude at time t;
- Bb,t is the bowen ratio at time t;
- Svf is the calculated sky view factor;
