Tool 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. doi:10.1016/S0166-2481(08)00008-1.
Gerlitz, L., Conrad, O., Böhner, J. (2015): Large scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural network based approach. Earth System Dynamics, 6, 1-21. doi:10.5194/esd-6-61-2015.

Author: J.Boehner, A.Ringeler (c) 2008, O.Conrad (c) 2011
Menu: Terrain Analysis|Climate and Weather

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Elevation	Grid, input	`DEM`	-	-
	Wind Direction (*)	Grid, input, optional	`DIR`	Direction into which the wind blows, starting with 0 for North and increasing clockwise.	-
	Wind Speed (*)	Grid, input, optional	`LEN`	-	-
Output	Wind Effect	Grid, output	`EFFECT`	-	-
Output	Effective Air Flow Heights (*)	Grid, output, optional	`AFH`	-	-
Options	Grid System	Grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	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 <double>] [-EFFECT <str>] [-AFH <str>] [-MAXDIST <double>] [-DIR_CONST <double>] [-OLDVER <str>] [-ACCEL <double>] [-PYRAMIDS <str>]
  -DEM:<str>         	Elevation
	Grid, input
  -DIR:<str>         	Wind Direction
	Grid, input, optional
  -DIR_UNITS:<str>   	Wind Direction Units
	Choice
	Available Choices:
	[0] radians
	[1] degree
	Default: 0
  -LEN:<str>         	Wind Speed
	Grid, input, optional
  -LEN_SCALE:<double>	Scaling
	Floating point
	Default: 1.000000
  -EFFECT:<str>      	Wind Effect
	Grid, output
  -AFH:<str>         	Effective Air Flow Heights
	Grid, output, optional
  -MAXDIST:<double>  	Search Distance [km]
	Floating point
	Minimum: 0.000000
	Default: 300.000000
  -DIR_CONST:<double>	Constant Wind Direction
	Floating point
	Default: 135.000000
  -OLDVER:<str>      	Old Version
	Boolean
	Default: 0
  -ACCEL:<double>    	Acceleration
	Floating point
	Minimum: 1.000000
	Default: 1.500000
  -PYRAMIDS:<str>    	Elevation Averaging
	Boolean
	Default: 0