Average calculation model (Heat Stress Overlay): Difference between revisions

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The [[Wind_speed_(Heat_Overlay)|wind speed]] and [[Wind_direction_(Heat_Overlay)|direction]], measured at a weather station, are used to determine the window for averaging.  
The [[Wind speed (Heat Stress Overlay)|wind speed]] and [[Wind direction (Heat Stress Overlay)|direction]] are used to determine the window for averaging values around a cell. Commonly, the values at a reference [[weather station (Heat Stress Overlay)|weather station]] are used. In calculations with a low wind speed, an cell-centered averaging window is used. For high wind speeds, an oblong averaging window is used, offsetting the cell along the wind direction.
If the wind speed is:
* < 1.5 meter per second, the window is cell centered: 700x700 meters;
* >= 1.5 meter per second, the window is 1100 x 500 meters, centered at 1000 x 250 x 100 x 250, where the long edge 1000 is opposite of the wind direction.
[[File:Average_window_nowind_(Heat_Overlay).png|350px]][[File:Average_window_wind_(Heat_Overlay).png|350px]]


The following parameters are averaged by this window:
Wind speed:
* Vegetation fraction, originating as the fraction green/vegetation present in Buildings and Terrains;
* < 1.5 meter per second, the window is square and cell centered
* Sky view factor, calculated by the Sky view factor calculation model;
* >= 1.5 meters per second, the window is oblong and offset toward the wind direction to account for wind effects.
 
The averaging windows are described below:
 
{|class=wikitable
! Window
! Model
! Low wind speeds
! High wind speeds
|-
| {{anchor|Large window|Large window}}
|
* [[Vegetation avg result type (Heat Stress Overlay)|Vegetation fraction]], based on the fraction [[Vegetation fraction (Heat Stress Overlay)|green/vegetation]] present in Buildings and Terrains
* [[Sky view avg result type (Heat Stress Overlay)|Sky view factor]], calculated by the [[Sky view factor calculation model (Heat Stress Overlay)|sky view factor calculation model]]
| [[File:Average window nowind (Heat_Overlay).png|250px|thumb|700x700 meters, cell-centered]]
| [[File:Average window wind (Heat Overlay).png|250px|thumb|1100x500 meters, centered at 1000x250x100x250]]
|-
| {{anchor|Small window|Small window}}
|
* [[Wind speed result type (Heat Stress Overlay)|Wind speed]], based on the wind direction and wind speed parameters configured for the overlay.
| [[File:Wind_window_sq(Heat_Overlay).png|250px|thumb|175x175 meters, cell-centered]]
| [[File:Wind_window_(Heat_Overlay).png|250px|thumb|280x140 meters, centered at 210x70x70x70]]
|}
 
{{article end
|seealso=
* [[Vegetation avg result type (Heat Stress Overlay)|Vegetation fraction average result type]]
* [[Sky view avg result type (Heat Stress Overlay)|Sky view factor average result type]]
}}
{{Template:HeatOverlay_formula_nav}}

Latest revision as of 10:50, 13 October 2026

The wind speed and direction are used to determine the window for averaging values around a cell. Commonly, the values at a reference weather station are used. In calculations with a low wind speed, an cell-centered averaging window is used. For high wind speeds, an oblong averaging window is used, offsetting the cell along the wind direction.

Wind speed:

  • < 1.5 meter per second, the window is square and cell centered
  • >= 1.5 meters per second, the window is oblong and offset toward the wind direction to account for wind effects.

The averaging windows are described below:

Window Model Low wind speeds High wind speeds
Large window
700x700 meters, cell-centered
1100x500 meters, centered at 1000x250x100x250
Small window
  • Wind speed, based on the wind direction and wind speed parameters configured for the overlay.
175x175 meters, cell-centered
280x140 meters, centered at 210x70x70x70

See also

Heat Stress Module
Heat Stress Module
Tutorials
Overview
Theory
Benchmarks
Group
Formulas
UHI • Temperatures • Diffuse radiation • PET
Calculation models
Foliage height • Sky view factor • Shade • Average vegetation and sky view factor
Related
Calculation models and formulas • Feature attributes • Model attributes • Result types


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