irradiance: Produce a model of irradiance for an entire study area or...
In mtalluto/NSmetabolism: N-Station Stream Metabolism Modelling

Description Usage Arguments Details Value

Produce a model of irradiance for an entire study area or selected control points

irradiance(
  dem,
  output_points,
  times,
  timezone,
  use_existing = FALSE,
  dem_name = "dem",
  slope_name = "slope",
  aspect_name = "aspect",
  lon_name = "longitude",
  horizon_pars = list(step = 30, bufferzone = 200, maxdistance = 5000, horBaseName =
    "horizonAngle"),
  newSession = FALSE,
  gisBase
)

`dem`	A sp::SpatialGridDataFrame or raster::RasterLayer object giving the digital elevation model of the study area.
`output_points`	A set out output points; either a sp::SpatialPoints object or a raster mask.
`times`	A vector of POSIXct objects giving the dates and times at which to compute irradiance. These should be given in local (to the DEM) time
`timezone`	An integer giving the offset in hours from UTC that applies to the DEM; see the manual for r.sun for details
`use_existing`	logical, if TRUE then existing slope, aspect, longitute, and horizon rasters will be used, if FALSE then they will be recomputed
`dem_name`	character; this parameter (and similar name parameters) tell GRASS what names to use for the rasters needed for the analysis; they must exist in the GRASS location/mapset if `use_existing == TRUE`.
`horizon_pars`	List of arguments for GRASS74's r.horizon; see the GRASS GIS help files ] if you wish to change the defaults.
`newSession`	Boolean, if TRUE a new grass session will be started even if one already exists
`gisBase`	character; the location of the GRASS installation (see WatershedTools::GrassSession)

Requires an existing installation of GRASS7, as well as the rgrass7 package. It is first necessary to run rgrass7::initGRASS. Recommended settings for initGRASS include home = tempdir() and SG = SpatialGrid(dem_gridded). To produce the gridded DEM from a raster, use: dem_gridded <- SpatialPoints(dem) gridded(dem_gridded) <- TRUE

Note that running the light model can be extremely slow for large study areas and/or high-resolution DEMs and/or long time series.

It is strongly recommended to use the output_points argument to set a list of locations at which to compute the output, otherwise memory usage can be extreme. For rasters, output will be returned for all non-NA cells.

A matrix, one row per output point, one column per date/time for computation. Column names are the integer values of the date/time, rownames are the coordinates of the point

mtalluto/NSmetabolism documentation built on May 3, 2021, 7:51 p.m.