Hi Majid,

if you do not want to write the code yourself, you may have a look at the Climate Data Operators at https://code.zmaw.de/projects/cdo.

Best regards,

Klemens

Hi Majid, Klemens is right: CDO is a very useful tool to manage grib (and netCDF) files and to reduce the information you need in a simple format to load in your plotting environment. Many of the climate operators you could need are already available within CDO.

Best,

enrico

Thank you very much for your answers my friends. But ...

Isn`t any software in windows OS  which has graphical user interface for decoding the grib files and get all data !? because I dont know anything about programming and write a command in CDO for example, and I have not enough time for learning thease. If there is not something as I said , Can anyone help me in decoding files with CDO (just as a guideline) ? 

Many Thanks. 

Hi Majid,

I join the previous comments in that CDO is the best option. In addition, I would add that maybe the OS you mention is not the ideal to deal with this kind of topic/problem... but that's just an opinion. However, here you have a pair of additional options.

1) You could try PANOPLY from the NASA. I have ever tried it and I was able to manage GRIB files, but I can not tell you match about it. It runs over JAVA and it is available for the OS you intend to use. There you will find it:

http://www.giss.nasa.gov/tools/panoply/

This could be a good option as long as you do not need to process large numbers of files...

2) I insist that if you will be working with ECMWF grib files CDO the best option. However for certain non very standard variables (directional/spectral wave data...) you may need to use the ECMWF GRIB-API directly. This approach will require considerably more time and effort. You will find the GRIB API here:

https://software.ecmwf.int/wiki/display/GRIB/Home

and also within the libs available for CDO (libs4cdo-xxxxxx):

https://code.zmaw.de/projects/cdo/files

With regard to the documentation you were asking for... I am afraid you will have to dive into the documentation of the different tools already mentioned...

Thanks all for your attention.

This page ( http://en.wikipedia.org/wiki/GRIB )  suggest many softwares in manipulation of grib files. 

thanks.

Hi Majid,

The best tools for working with grib files are tools specially used under Linux environment, like cdo or the ECMWF GRIB-API -  in fact, the GRIB API has a specific command, grib_to_netcdf (https://software.ecmwf.int/wiki/display/GRIB/grib_to_netcdf) which allows you to convert the files into netcdf files, which (I believe) are easier to use.

If you want a graphical user interface, the official graphical tool for ECMWF is Metview (https://software.ecmwf.int/wiki/display/METV/Metview) but, again, is for Linux environment.

The only graphical tool I have used for Windows OS is Panoply, quite easy to install and quite easy to use, specially for drawing maps and studying the file structure, but be aware of its behaviour when reading dates: if you are using forecasts, Panoply will mix the dates.

You may take the help of the following script which uses cdo to convert grib to netcdf format data of ecmwf. Happy working and best wishes

OP Sharma

#!/bin/sh

# This scripts extracts data for a particular day as specified.

# Yearwise files are created using the python script selectFileName.py

# Data of a particular day are extracted using cdo command seldate

# Then ensemble average of the day files is achieved using the cdo command

# ECMWF data are stored in grib format

# Atmospheric Variables details: Code Name units

# 129 Z geopotential m^2/s^2

# 130 T temperature K

# 133 q Specific Humidity kg/kg

# 135 w Vertical velocity Pa/sec

# 131 U component of wind m/s

# 132 V component of wind m/s

# ECMWF data: Z = gz (z is the height) ; w = dp/dt (omega)

# ECdata file names: stored in a file created by this shell

\rm file*

\rm fselect.sh ensavg*

\rm ECDYN_ensavg* ECSFC_ensavg*

pathfls=pwd

cat pathfls

datadir='FreeAgentDrive'

dir=/Volumes/$datadir

ls $dir > file_names

# file_names is INPUT to selectFileName.py. This python script is executed

# to generate links to 12 years of EC files from which data for

# a particular date are extracted

base_name='ei_oper_an_pl_075x075'

start_year=1998

numyears=12

day='01'

month='05'

time='T12:00:00'

year=$start_year

count=1

while [ $count -le $numyears ]

do

DATE=$year$month$day

echo $DATE >> file_dates

echo $year >> file_years

count=`expr $count + 1`

year=`expr $year + 1`

done

year=$start_year

count=1

while [ $count -le $numyears ]

do

DATE1=$year'-'$month'-'$day$time

DATE2=$year'-'$month'-'$day$time

echo $count $year $DATE1 $DATE2

dayfile='filen'$count

workfile='filedec'$year

echo $workfile $dayfile

cdo seldate,$DATE1,$DATE2 $workfile $dayfile

count=`expr $count + 1`

year=`expr $year + 1`

done

ofile='ensavg_dynfile'$month$day

cdo ensmean filen[1-12] $ofile

## convert $ofile from grib to netcdf format

ncfile='ECDYN_ensavg'$month$day'.nc'

cdo -f nc copy $ofile $ncfile

nufile='ECDYNAV'$month$day'.nc'

cdo chname,var129,GEOP,var130,TEMP,var133,hus,var135,w,var131,U,var132,V $ncfile $nufile

# End of Atmospheric data extraction at pressure levels & ave initial fields

The script may not work as such as I use the names which may differ with those of yours.

If you just want to visualize your data, Panoply from Nasa is what you need:

http://www.giss.nasa.gov/tools/panoply/

I confirm CDO as a preferable tool to manage grib files. As a first step you can check the grib content through the command "cdo -sinfo nomefile.grib". For more info about CDO:  https://code.zmaw.de/projects/cdo

I used IDV for viewing and mapping GRIB files. IDV is a free software.

ArcGIS has an extension ("Interoperability Extension", not part of the standard package though) to read and display GRB files on a base map. Map Algebra -> Raster Calculator can then do math with multiple layers of data (i.e. multiple data sets) stacked on top of each other, if that is what you need to do.

PS: Klemens, greetings to my old home university :-)

I also confirm CDO as preferable tool. For quick info I use most frequently  the sinfon operator. I think that the GrADS interface gradsdes operator with the table notation, like

cdo -t ecmwf gradsdes mygrib,

which creates grads description and index files is also very pleasant.

 Thank you so much Toni!! It was very helpful to solve my problem for grib file on ArcGIS.