Section: 4.5 CDO Utilities

4.5 CDO Utilities

The CDO (Climate Data Operators) package is a collection of command line operators to manipulate and analyze climate model data.

The Max Planck Institute for Meteorology has developed CDO, which supports GRIB, CF-compliant netCDF, and several other formats. There are more than 400 operators available. CDO supports rectangular, curvilinear and unstructured grid types.

CDO includes the ability to pipe an output stream of one operator into another, eliminating unnecessary I/O and temporary files, and allowing parallel processing.

Categories of CDO operators include:

File information	Print information about datasets
File operations	Copy, split and merge datasets
Selection	Select parts of a dataset
Comparision	Compare datasets
Modification	Modify datasets
Arithmetic	Arithmeticly process datasets
Statistical values	Ensemble, field, vertical and time range statistic
Regression	Detrend of time series
Interpolation	Field, vertical and time interpolation
Transformation	Spectral transformation
Formatted I/O	ASCII input and output
Climate indices	ECA Indices of Daily Temperature and Precipitation Extremes

Some examples:

To print information and simple statistics for each field of ifile:
```
     cdo info ifile
  
```
To print the max absolute and relative difference for each field of two datasets ifile1 and ifile2 use:
```
     cdo diff ifile1 ifile2
  
```
To change the format of a dataset ifile to the netCDF file ofile use:
```
    cdo -f nc copy ifile  ofile.nc
  
```
To select the region with the longitudes from 120E to 90W and latitudes from 20N to 20S from all input fields in ifile and write the result to ofile use:
```
    cdo sellonlatbox,120,-90,20,-20 ifile ofile
  
```

To compute the ensemble mean over 6 input files use and write in ofile:

    cdo ensmean ifile1 ifile2 ifile3 ifile4 ifile5 ifile6 ofile

NetCDF-4 note: CDO supports the netCDF-4 classic data model with compression.

2008 Unidata NetCDF Workshop for Developers and Data Providers > NetCDF Utilities