README

Simple library to read GRIB2 WMO format with using FFI.

Purpose

This library shows an example of how to use adapt libeccodes for using with PHP FFI extension to save developers time.

Install

composer require okvpn/grib2-eccodes

Install libaec-dev

apt install libaec-dev

(Optional) Install eccodes lib. See https://confluence.ecmwf.int/display/ECC/ecCodes+installation.

But to simplify distribution, the libeccodes is build-in with data eccodes.tar.gz. It will be extracted to tmp dir.

Usage

# Get grib index data 
# https://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gfs.<date>/<time>/atmos/gfs.t<time>z.pgrb2b.1p00.f<xxx>.idx

170:9120456:d=2023081906:RH:575 mb:3 hour fcst:
171:9195051:d=2023081906:TCDC:575 mb:3 hour fcst:
172:9235360:d=2023081906:VVEL:575 mb:3 hour fcst:
173:9325082:d=2023081906:DZDT:575 mb:3 hour fcst:
174:9400873:d=2023081906:UGRD:575 mb:3 hour fcst:
175:9480146:d=2023081906:VGRD:575 mb:3 hour fcst:
176:9560543:d=2023081906:ABSV:575 mb:3 hour fcst:
177:9632016:d=2023081906:CLWMR:575 mb:3 hour fcst:

Download Grib2 archive

$curl = new CurlHttpClient();
// Select 174:9400873:d=2023081906:UGRD:575 mb:3 hour fcst:
// Use http 206 Partial Content feature to downlaod only one param
$res = $curl->request('GET', 'https://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gfs.<date>/<time>/atmos/gfs.t<time>z.pgrb2b.1p00.f003', ['headers' => ['Range' => 'bytes=9400873-9480145']]);

file_put_contents("VGRD.p1", $res->getContent())

require_once __DIR__ . '/vendor/autoload.php';

use FFI;
use Okvpn\Grib2\Grib2Reader;
use Okvpn\Grib2\LibEccodes;

LibEccodes::$libPath = "libeccodes.so"; // . use fill path if installed eccodes to custom path

$reader = new Grib2Reader();

$data = $reader->read("VGRD.p1");

print_r($data);


$matrix = $reader->read2D("VGRD.p1", lat1: 48, lat2: 57, lon1: 13, lon2: 36);
foreach ($matrix as $i => &$vals) {
    foreach ($vals as $j => &$val) {
        $val = ($s = strlen($val = round($val))) >= 3 ? $val : $val . str_repeat(' ', 3-$s);
    }
}

Output

5   6   5   3   3   3   3   5   4   4   5   5   5   7   7   7   4   9   6   6   9   5   7   8  
5   7   5   2   0   2   2   1   -0  1   2   2   4   4   5   6   6   7   6   6   5   5   6   6  
4   6   5   3   2   2   0   0   1   2   1   1   2   3   2   2   3   1   1   1   2   2   5   4  
5   5   5   3   3   2   2   1   3   5   6   5   4   3   3   2   -0  -1  -1  -2  -2  -3  -3  -1 
6   6   5   3   3   3   2   4   4   5   4   4   4   4   2   1   0   -0  -0  -2  -1  -1  -3  -4 
5   6   6   1   2   2   2   3   4   4   3   2   3   2   2   3   0   0   -0  -2  -1  -1  -2  -3 
5   4   1   1   1   0   1   4   3   1   2   1   2   3   4   3   2   0   -1  -0  -2  -2  -2  -3 
4   1   1   1   0   1   2   2   2   1   2   2   3   2   3   3   1   0   -0  -1  -2  -3  -4  -3 
2   0   1   -1  -0  1   2   1   0   1   1   2   3   3   1   1   0   -0  0   0   -1  -3  -5  -4 
-1  -1  -3  -2  -0  -1  -2  -2  -2  -1  0   2   2   2   2   1   0   0   -0  -1  -1  -3  -5  -5 

License

MIT License.