Please cite SAGA whenever you use it for your publications:

This tool reimplements the Wind Shelter Index proposed by Plattner et al. (2004), that has originally been implemented within the RSAGA package.

Name	Type	Identifier	Description	Constraints
Input
Elevation	grid, input	ELEVATION
Output
Wind Shelter Index	grid, output	SHELTER
Options
Unit	choice	UNIT		Available Choices: [0] degree [1] radians Default: 0
Wind Direction	floating point number	DIRECTION	The direction [degree] into which the wind blows.	Default: 135
Tolerance	floating point number	TOLERANCE	The tolerance angle [degree] to the left and right of the direction angle.	Minimum: 0.000000 Maximum: 90.000000 Default: 5
Distance	floating point number	DISTANCE	[cells]	Minimum: 1.000000 Default: 5
Quantile	floating point number	QUANTILE	Set quantile to one to get the maximum slope angle.	Minimum: 0.000000 Maximum: 1.000000 Default: 1
Include Negative Slopes	boolean	NEGATIVES		Default: 0
Method	choice	METHOD		Available Choices: [0] windward [1] leeward Default: 0