Wind calculation model (Heat Stress Overlay) - Revision history

Frank@tygron.nl at 14:23, 13 April 2026

2026-04-13T14:23:15Z

← Older revision		Revision as of 14:23, 13 April 2026
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	* [[Wind speed result type (Heat Stress Overlay)\|Wind speed result type]]		* [[Wind speed result type (Heat Stress Overlay)\|Wind speed result type]]
	}}		}}
	{{~~Template:~~HeatOverlay formula nav}}		{{HeatOverlay formula nav}}

Frank@tygron.nl at 14:23, 13 April 2026

2026-04-13T14:23:08Z

← Older revision		Revision as of 14:23, 13 April 2026
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	[[File:Wind_model_(Heat_Overlay).png\|400px\|thumb\|Frontal surface and average obstacle heights are both parameters for the wind translation to 1.2 meters above ground.]]		[[File:Wind_model_(Heat_Overlay).png\|400px\|thumb\|Frontal surface and average obstacle heights are both parameters for the wind translation to 1.2 meters above ground.]]
	The wind speed on street level (1.2 meter) is calculated using a translation of the 10 meter [[Wind_speed_(~~Heat_Overlay~~)\|wind speed]] measured at a [[weather station (Heat Stress Overlay)\|weather station]]. A single reduction field per wind direction can be calculated, which in turn can be multiplied with the 10 meter wind speed to obtain the wind speed at street level. The calculation model is based on the McDonald (2000) method for wind in cities. It uses the vertical surfaces of buildings perpendicular to the wind direction to determine in what way the wind speed is slowed down. The {{~~Template:Heat_DPRA_Report~~}} has extended this method with perpendicular vertical tree surfaces as well.<br style="clear:right">		The wind speed on street level (1.2 meter) is calculated using a translation of the 10 meter [[Wind_speed_(Heat_Stress Overlay)\|wind speed]] measured at a [[weather station (Heat Stress Overlay)\|weather station]]. A single reduction field per wind direction can be calculated, which in turn can be multiplied with the 10 meter wind speed to obtain the wind speed at street level. The calculation model is based on the McDonald (2000) method for wind in cities. It uses the vertical surfaces of buildings perpendicular to the wind direction to determine in what way the wind speed is slowed down. The {{Heat DPRA Report}} has extended this method with perpendicular vertical tree surfaces as well.<br style="clear:right">

	==Implementation==		==Implementation==
	The calculation implemented in the {{software}} differs from the implementation described by the {{~~Template:Heat_DPRA_Report~~}}. Specifically, rather than performing the described cubic interpolation from coarse grids to more detailed grids, all operation are done on a detailed grid.		The calculation implemented in the {{software}} differs from the implementation described by the {{Heat DPRA Report}}. Specifically, rather than performing the described cubic interpolation from coarse grids to more detailed grids, all operation are done on a detailed grid.

	===Averaging window===		===Averaging window===
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	<math>\lambda_{buildings} = S_{frontal} / n_{cells}</math>		<math>\lambda_{buildings} = S_{frontal} / n_{cells}</math>

	For <math>\lambda_{foliage}</math> the same process is repeated, but then with [[~~Foliage_height_calculation_model_~~(~~Heat_Overlay~~)\|foliage heights]] instead of Building heights.		For <math>\lambda_{foliage}</math> the same process is repeated, but then with [[Foliage height calculation model (Heat Stress Overlay)\|foliage heights]] instead of Building heights.

	====Determine the combined frontal surface compactness factor====		====Determine the combined frontal surface compactness factor====
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	The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large. This result is less wind and an increase in heat around woods.		The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large. This result is less wind and an increase in heat around woods.

	To address this issue, a [[~~Wind_decline_angle_~~(~~Heat_Overlay~~)\|WIND_DECLINE_ANGLE]] can be applied to smooth the wind flow, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[Wind decline angle (Heat Stress Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the wind flow, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Frank@tygron.nl at 11:43, 13 April 2026

2026-04-13T11:43:12Z

← Older revision		Revision as of 11:43, 13 April 2026
Line 1:		Line 1:
	[[File:Wind_model_(Heat_Overlay).png\|400px\|thumb\|Frontal surface and average obstacle heights are both parameters for the wind translation to 1.2 meters above ground.]]		[[File:Wind_model_(Heat_Overlay).png\|400px\|thumb\|Frontal surface and average obstacle heights are both parameters for the wind translation to 1.2 meters above ground.]]
	The wind speed on street level (1.2 meter) is calculated using a translation of the 10 meter [[Wind_speed_(Heat_Overlay)\|wind speed]] measured at a [[weather station (Heat Overlay)\|weather station]]. A single reduction field per wind direction can be calculated, which in turn can be multiplied with the 10 meter wind speed to obtain the wind speed at street level. The calculation model is based on the McDonald (2000) method for wind in cities. It uses the vertical surfaces of buildings perpendicular to the wind direction to determine in what way the wind speed is slowed down. The {{Template:Heat_DPRA_Report}} has extended this method with perpendicular vertical tree surfaces as well.<br style="clear:right">		The wind speed on street level (1.2 meter) is calculated using a translation of the 10 meter [[Wind_speed_(Heat_Overlay)\|wind speed]] measured at a [[weather station (Heat Stress Overlay)\|weather station]]. A single reduction field per wind direction can be calculated, which in turn can be multiplied with the 10 meter wind speed to obtain the wind speed at street level. The calculation model is based on the McDonald (2000) method for wind in cities. It uses the vertical surfaces of buildings perpendicular to the wind direction to determine in what way the wind speed is slowed down. The {{Template:Heat_DPRA_Report}} has extended this method with perpendicular vertical tree surfaces as well.<br style="clear:right">

	==Implementation==		==Implementation==
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	===Averaging window===		===Averaging window===
	{{main\|Average calculation model (Heat Overlay)}}		{{main\|Average calculation model (Heat Stress Overlay)}}
	The average wind speed is based on an average of wind speeds across a larger area. The window for averaging is established based on wind speed and direction. For slow wind speeds (below 1.5m/s), a wind speed of 175x175m is used. For high wind speeds, a window of 280x140m if used.		The average wind speed is based on an average of wind speeds across a larger area. The window for averaging is established based on wind speed and direction. For slow wind speeds (below 1.5m/s), a wind speed of 175x175m is used. For high wind speeds, a window of 280x140m if used.

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	<math>u_{1.2 corr} = u_{10} \cdot ((u_{1.2} - 0.0796) \cdot 0.9175 + 0.1254)</math>		<math>u_{1.2 corr} = u_{10} \cdot ((u_{1.2} - 0.0796) \cdot 0.9175 + 0.1254)</math>

	This corrected value is used in the formula for [[PET formulas (Heat Overlay)\|PET]].		This corrected value is used in the formula for [[PET formulas (Heat Stress Overlay)\|PET]].

	==Improved wind model==		==Improved wind model==
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	\|seealso=		\|seealso=
	* [[Wind speed result type (Heat Overlay)\|Wind speed result type]]		* [[Wind speed result type (Heat Stress Overlay)\|Wind speed result type]]
	}}		}}
	{{Template:HeatOverlay formula nav}}		{{Template:HeatOverlay formula nav}}

Frank@tygron.nl: Frank@tygron.nl moved page Wind calculation model (Heat Overlay) to Wind calculation model (Heat Stress Overlay)

2026-04-13T11:38:26Z

Frank@tygron.nl moved page Wind calculation model (Heat Overlay) to Wind calculation model (Heat Stress Overlay)

← Older revision	Revision as of 11:38, 13 April 2026
(No difference)

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:43:47Z

Improved wind model

← Older revision		Revision as of 11:43, 8 November 2024
Line 122:		Line 122:
	The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large. This result is less wind and an increase in heat around woods.		The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large. This result is less wind and an increase in heat around woods.

	To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the ~~surface~~, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the wind flow, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:43:23Z

Improved wind model

← Older revision		Revision as of 11:43, 8 November 2024
Line 120:		Line 120:

	==Improved wind model==		==Improved wind model==
	The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.		The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large. This result is less wind and an increase in heat around woods.

	To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:42:39Z

Improved wind model

← Older revision		Revision as of 11:42, 8 November 2024
Line 120:		Line 120:

	==Improved wind model==		==Improved wind model==
	The roughness of the frontal surface affects wind speed. In the original DPRA ~~model~~, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.		The roughness of the frontal surface affects wind speed. In the original {{Heat DPRA Report}}, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.

	To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:42:11Z

Improved wind model

← Older revision		Revision as of 11:42, 8 November 2024
Line 122:		Line 122:
	The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.		The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.

	To address this issue, a [[~~WIND_DECLINE_ANGLE\|~~Wind_decline_angle_(Heat_Overlay)]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[Wind_decline_angle_(Heat_Overlay)\|WIND_DECLINE_ANGLE]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:41:57Z

Improved wind model

← Older revision		Revision as of 11:41, 8 November 2024
Line 122:		Line 122:
	The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.		The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.

	To address this issue, a [WIND_DECLINE_ANGLE\|Wind_decline_angle_(Heat_Overlay)] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [[WIND_DECLINE_ANGLE\|Wind_decline_angle_(Heat_Overlay)]] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.

Maxim@tygron.com: /* Improved wind model */

2024-11-08T11:41:47Z

Improved wind model

← Older revision		Revision as of 11:41, 8 November 2024
Line 122:		Line 122:
	The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.		The roughness of the frontal surface affects wind speed. In the original DPRA model, the frontal surface is derived from very basic tree shapes. However, when utilizing more detailed foliage data, such as AI-detected individual trees, the frontal surface becomes excessively large.

	To address this issue, a WIND_DECLINE_ANGLE can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.		To address this issue, a [WIND_DECLINE_ANGLE\|Wind_decline_angle_(Heat_Overlay)] can be applied to smooth the surface, leading to a more accurate representation of the frontal surface and producing more realistic values in wooded areas or parks.