45 lines
1.4 KiB
Nix
45 lines
1.4 KiB
Nix
{ writers, coreutils, grib2json, curl, jq, findutils, imagemagick }:
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writers.writeDashBin "nomads-cloud" ''
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prefix=$(mktemp -d)
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grib_path=$prefix/clouds.grib
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json_path=$prefix/clouds.json
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pgm_path=$prefix/clouds.pgm
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png_path=$1
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mkdir -p "$prefix"
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date=$(${coreutils}/bin/date +%Y%m%d)
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for hour in 18 12 06 00; do
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url="https://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_0p25_1hr.pl?file=gfs.t''${hour}z.pgrb2.0p25.anl&lev_entire_atmosphere_%5C%28considered_as_a_single_layer%5C%29=on&var_CWAT=on&leftlon=-180&rightlon=180&toplat=90&bottomlat=-90&dir=%2Fgfs.''${date}%2F''${hour}%2Fatmos"
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echo "$url"
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${curl}/bin/curl -fsS "$url" > "$grib_path"
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if [ "$?" -eq 0 ]; then
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break
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fi
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done
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${grib2json}/bin/grib2json --data "$grib_path" > "$json_path"
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width=$(${jq}/bin/jq '.[0].header.nx' < "$json_path")
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height=$(${jq}/bin/jq '.[0].header.ny' < "$json_path")
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# The maximum gray value. Must be bigger than 0 and less than 65536.
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maxval=1000
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# pgm - Netpbm grayscale image format
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# http://netpbm.sourceforge.net/doc/pgm.html
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{
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echo P2
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echo "$width $height"
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echo "$maxval"
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cat "$json_path" |
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${jq}/bin/jq --argjson maxval "$maxval" -c '
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((.[0].data[]) * $maxval | round)
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' |
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${findutils}/bin/xargs -n "$width"
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} > "$pgm_path"
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${imagemagick}/bin/convert -roll +50% "$pgm_path" "$png_path"
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rm -r "$prefix"
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''
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