Drawing wind barbs
Canvas example from the arrows and barbs section.
The data is taken from the GFS model, following these steps:
- Download at a link like this one (dates may not be available): http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gfs.2016112400/
- Running gdalinfo gfs.t00z.sfluxgrbf00.grib2, see that the bands 50 and 51 are UGRD and VGRD at 10-HTGL (surface wind)
- Run gdal_translate -b 50 -b 51 -projwin 17 50 47 29 gfs.t00z.sfluxgrbf00.grib2 /tmp/gfs.tiff
- Note that the geotiff-js library has some problems with compression
- This image, taken from weatheronline, shows that the barbs are coherent with other source images