spatialEco (version 2.0-2)

trasp: Solar-radiation Aspect Index

Description

Calculates the Roberts and Cooper (1989) Solar-radiation Aspect Index

Usage

trasp(x, ...)

Value

A terra SpatRaster object of Roberts and Cooper (1989) Solar-radiation Aspect Index

Arguments

x

A terra SpatRaster object

...

Additional arguments passed to terra::app

Author

Jeffrey S. Evans <[e-mail]>

Details

Roberts and Cooper (1989) rotates (transforms) the circular aspect to assign a value of zero to land oriented in a north-northeast direction, (typically the coolest and wettest orientation), and a value of one on the hotter, dryer south-southwesterly slopes. The result is a continuous variable between 0 - 1. The metric is defined as: trasp = ( 1 - cos((pi/180)(a-30) ) / 2 where; a = aspect in degrees

References

Roberts. D.W., and Cooper, S.V. (1989). Concepts and techniques of vegetation mapping. In Land Classifications Based on Vegetation: Applications for Resource Management. USDA Forest Service GTR INT-257, Ogden, UT, pp 90-96

Examples

library(terra)
elev <- rast(system.file("extdata/elev.tif", package="spatialEco"))
  s <- trasp(elev)
    plot(s)