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d.rast.arrow at work

GRASS used together with R-stats provides a powerful toolset to analyse meteorological time series and to perform spatio-temporal interpolation.

  • d.barb: Displays wind barbs or variable length straw diagrams given either two raster maps, or vector point data. Like d.rast.arrow, input data is given as magnitude and direction, unlike d.rast.arrow you can also feed it u,v component data.
See also Visualizing Terrain Surface Indicies with Scaled Arrows.
  • r.series - useful for time series analysis of raster data.
  • - useful for 2D spline interpolation between sparse data points.


Wind meteorological data usually follow a convention different from the GRASS one. First, the wind direction expresses the direction which wind blows FROM and not TO. Second, the convention on directions differs from the one adopted by GRASS (for aspect, flow direction, etc.), which is the mathematical or Cartesian convention: CCW from the +x axis.