Average calculation model (Heat 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_Overlay)|wind speed]] and [[Wind_direction_(Heat_Overlay)|direction]], measured at a weather station, are used to determine the window for averaging values around a cell. In calculations with a low wind speed, an cell-centered averaging window is used. In calculations with a high wind speed, an oblong rectangle is used for averaging, with the cell in question offset towards the far side along the line of 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, based on the fraction [[Vegetation fraction (Heat Overlay)|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 (Heat Overlay)|Sky view factor calculation model]];
* >= 1.5 meter per second, the window is oblong.
 
{|class=wikitable
! Window
! Model
! Low wind speeds
! High wind speeds
|-
| Large window
|
* Vegetation fraction, based on the fraction [[Vegetation fraction (Heat Overlay)|green/vegetation]] present in Buildings and Terrains
* Sky view factor, calculated by the [[Sky view factor calculation model (Heat 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]]
|-
| Small window
|
* Wind speed, based on the [[Wind calculation model (Heat Overlay)|wind direction]] configured as [[Wind speed (Heat Overlay)|wind speed]] parameter for the Overlay's calculation.
| [[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]]
|}


==See also==
==See also==

Revision as of 13:55, 18 December 2019

The wind speed and direction, measured at a weather station, are used to determine the window for averaging values around a cell. In calculations with a low wind speed, an cell-centered averaging window is used. In calculations with a high wind speed, an oblong rectangle is used for averaging, with the cell in question offset towards the far side along the line of the wind direction.

Wind speed:

  • < 1.5 meter per second, the window is square and cell centered
  • >= 1.5 meter per second, the window is oblong.
Window Model Low wind speeds High wind speeds
Large window
700x700 meters, cell-centered
1100x500 meters, centered at 1000x250x100x250
Small window
175x175 meters, cell-centered
280x140 meters, centered at 210x70x70x70

See also