Module Wind Effect (Windward / Leeward Index)
The 'Wind Effect' is a dimensionless index. Values below 1 indicate wind shadowed areas whereas values above 1 indicate areas exposed to wind, all with regard to the specified wind direction. Wind direction, i.e. the direction into which the wind blows, might be either constant or variying in space, if a wind direction grid is supplied.
References:
- Boehner, J., Antonic, O. (2009): 'Land-surface parameters specific to topo-climatology'. in: Hengl, T., Reuter, H. (Eds.): 'Geomorphometry - Concepts, Software, Applications'. Developments in Soil Science, Volume 33, p.195-226, Elsevier.
- Author: J.Boehner, A.Ringeler (c) 2008, O.Conrad (c) 2011
- Specification: grid
- Menu: Terrain Analysis|Climate and Weather
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | Grid (input) | DEM | - | - |
| Wind Direction (*) | Grid (optional input) | DIR | Direction into which the wind blows, starting with 0 for North and increasing clockwise. | - |
| Wind Speed (*) | Grid (optional input) | LEN | - | - |
| Output | Wind Effect | Grid (output) | EFFECT | - | - |
| Effective Air Flow Heights (*) | Grid (optional output) | AFH | - | - |
| Options | Wind Direction Units | Choice | DIR_UNITS | - | Available Choices:
[0] radians
[1] degree
Default: 0 |
| Scaling | Floating point | LEN_SCALE | - | Default: 1.000000 |
| Search Distance [km] | Floating point | MAXDIST | - | Minimum: 0.000000
Default: 300.000000 |
| Constant Wind Direction | Floating point | DIR_CONST | constant direction into the wind blows, given as degree | Default: 135.000000 |
| Old Version | Boolean | OLDVER | use old version for constant wind direction (no acceleration and averaging option) | Default: 0 |
| Acceleration | Floating point | ACCEL | - | Minimum: 1.000000
Default: 1.500000 |
| Elevation Averaging | Boolean | PYRAMIDS | use more averaged elevations when looking at increasing distances | Default: 0 |
| (*) optional |
Command-line
Usage: saga_cmd ta_morphometry 15 -DEM <str> [-DIR <str>] [-DIR_UNITS <str>] [-LEN <str>] [-LEN_SCALE <str>] [-EFFECT <str>] [-AFH <str>] [-MAXDIST <str>] [-DIR_CONST <str>] [-OLDVER <str>] [-ACCEL <str>] [-PYRAMIDS <str>]
-DEM:<str> Elevation
Grid (input)
-DIR:<str> Wind Direction
Grid (optional input)
-DIR_UNITS:<str> Wind Direction Units
Choice
Available Choices:
[0] radians
[1] degree
Default: 0
-LEN:<str> Wind Speed
Grid (optional input)
-LEN_SCALE:<str> Scaling
Floating point
Default: 1.000000
-EFFECT:<str> Wind Effect
Grid (output)
-AFH:<str> Effective Air Flow Heights
Grid (optional output)
-MAXDIST:<str> Search Distance [km]
Floating point
Minimum: 0.000000
Default: 300.000000
-DIR_CONST:<str> Constant Wind Direction
Floating point
Default: 135.000000
-OLDVER:<str> Old Version
Boolean
Default: 0
-ACCEL:<str> Acceleration
Floating point
Minimum: 1.000000
Default: 1.500000
-PYRAMIDS:<str> Elevation Averaging
Boolean
Default: 0