a small tutorial how to handle our datasets
If you want to see if you can handle our datasets please download this file:
This file contains the global sea level pressure for the year 1984.
Now we want to do some example operations on it using the tools.
Linux, Unix, Mac OSX
We want to use the CDOs.
Consider you'd like to have an ascii-text file out of the dataset. You get it by typing in your shell:
$user> cdo output pr-1984.grb > pr-1984.txt
Then you're able to use the data in your preferred programs.
Maybe you want to select smaller areas, e.g. Europe. Please do so by:
$user> cdo sellonlatbox,-50,60,30,75 pr-1984.grb pr-EUROPE.grb
(The structure is:
$user> cdo sellonlatbox,most western longitude,most eastern longitude,most southern latitude,most northern latitude inputfile outputfile
Please take care that western longitudes and southern latitudes are negative.)
If you want to change the output file format, do so by adding -f new format after cdo. You can change the format to netCDF, ieee(extra)... See the manuals for more information.
You can get grid descriptions by cdo griddes filename and time information by cdo showdate or showtime or showyear (and so on).
Of course you can use the CDOs to do some statistics.
If you need the yearly mean, then type in:
$user> cdo yearmean pr-1984.grb pr_yearmean.grb
The same would be for monthly means(monmean), daily means(daymean), seasonally means(seasmean)... There are quite a lot of more time functions. You´ll find them in the manual.
The next best thing you can do is to have a field mean weighted by area weights obtained by the input field:
$user> cdo fldmean pr-1984.grb pr_fieldmean.grb
There are still some more area functions, e.g. zonal means, field minimum, field maximum... You can read about them in the manual.
If you only want to have an ascii-text file then you should use the GRIBconverter.
Use your commandline-box and type in:
grbconv -i pr-1984.grb -o pr-1984.txt -t cona
-i stands for the inputfile, -o for the outputfile, -t means type of conversion (cona is convert to ascii).
If you want to use the CDOs you'll be able to do so by using "Cygwin". Then you are maybe able to install CDO properly on a windows machine.