A matlab implementation for converting grb2-files (grib2) into a simple CSV-file
Please note that this project is developed as a MATLAB - beginner - project. Therefore the design, syntax and the programming style might not be perfect.
Please note, that this grib2->CSV converter currently only works on grib2 files downloaded at : http://nomads.ncdc.noaa.gov/cgi-bin/ncdc-ui/define-collection.pl?model_sys=gfs4&model_name=gfs&grid_name=4
It is not tested for any other grib2-files.
The grib2-files provided by the upper url contain 0.5 degree gridded data. If you want to use it for different degree resolutions or for grib2-files from other sources please modify the way of calculating the array coordinates by the geographic coordinates in calcArrayCoordinates.m and the way you get the data out of the data-array inside grb2ToCSV.m.
This function can convert all grib2 files within the same directory like this file to one CSV-file (comma-separated-value text file). The CSV-file is named like the parameter "nameOfCSVFile_" and is created in the same folder like this file.
The CSV-file only contains the data of the coordinates "latitude_" and "longitude_" and only prints values of the variables which are defined at "relevantVars" in line 65.
The CSV-file has the structure : timestamp, nameOfVariable, value
The timestamp is automatically retrieved from the file-name.
A file name like : gfs_4_20140819_0000_006.grb2 leads to a
time stamp like : 19-Aug-2014 06:00:00
PLEASE NOTICE THAT THE NAMING OF THE GRB2 MUST HAVE THE STRUCTURE
gfs_4_20140819_0000_006.grb2
with
gfs_4_ = just an unimportant string
20140819 = date of forecast in YYYYMMDD
_= unimportant char
0000 = hours, when forecast was created
_= unimportant char
006 = hour of forecast (number of hours after hours, when
forecast was created)
FOR EXAMPLE :
if latitude_ = 54 and longitude_ = 8 and
relevantVars = [{'Temperature_height_above_ground';
'Relative_humidity_height_above_ground'}]
and the current directory contains the following grb2 files:
gfs_4_20140819_0000_000.grb2
gfs_4_20140819_0000_003.grb2
gfs_4_20140819_0000_006.grb2
gfs_4_20140819_0000_009.grb2
gfs_4_20140819_0000_012.grb2
gfs_4_20140819_0000_015.grb2
gfs_4_20140819_0000_018.grb2
a CSV-file is created like
19-Aug-2014 00:00:00, Temperature_height_above_ground , 289.30
19-Aug-2014 00:00:00, Relative_humidity_height_above_ground, 70.80
19-Aug-2014 03:00:00, Temperature_height_above_ground , 288.70
19-Aug-2014 03:00:00, Relative_humidity_height_above_ground, 70.20
19-Aug-2014 06:00:00, Temperature_height_above_ground , 288.20
19-Aug-2014 06:00:00, Relative_humidity_height_above_ground, 73.00
19-Aug-2014 09:00:00, Temperature_height_above_ground , 288.20
19-Aug-2014 09:00:00, Relative_humidity_height_above_ground, 75.60
19-Aug-2014 12:00:00, Temperature_height_above_ground , 288.50
19-Aug-2014 12:00:00, Relative_humidity_height_above_ground, 74.00
19-Aug-2014 15:00:00, Temperature_height_above_ground , 289.30
19-Aug-2014 15:00:00, Relative_humidity_height_above_ground, 66.50
19-Aug-2014 18:00:00, Temperature_height_above_ground , 288.80
19-Aug-2014 18:00:00, Relative_humidity_height_above_ground, 72.20
- clone this repository :
git clone git@github.com:gitdev1234/grb2ToCSV.git - install MATLAB (grb2ToCSV is only tested in MATLAB R2015b)
- copy example .grb2-files from /example to the directory where matlab
grb2ToCSV.m, main.m, ...are - open all files .m of this repository in matlab and add them to the MATLAB path
- execute main.m