CDO (Climate Data Operators) is a powerful command-line tool for processing NetCDF, GRIB, and other climate data formats. Below is a cheat sheet with commonly used commands and their explanations.
1. Viewing File Information
cdo info file.ncOutput:
File format : NetCDF
Variables : temperature, precipitation
Dimensions : time=365, lon=360, lat=180
2. Checking File Contents
cdo showname file.ncOutput:
temperature precipitation
3. Extracting a Time Slice
cdo seldate,2020-01-01,2020-01-31 input.nc output.ncExtracts data for January 2020 and saves to output.nc
4. Merging Multiple Files
cdo merge file1.nc file2.nc merged.ncCombines file1.nc and file2.nc into merged.nc
5. Calculating Monthly Means
cdo monmean input.nc monthly_means.ncCalculates monthly mean values and saves to monthly_means.nc
6. Calculating Annual Means
cdo yearmean input.nc annual_means.ncCalculates annual mean values and saves to annual_means.nc
7. Spatial Averaging
cdo fldmean input.nc spatial_avg.ncComputes the global mean of all grid points and saves to spatial_avg.nc
8. Subsetting Data by Region
cdo sellonlatbox,-10,10,30,50 input.nc subset.ncExtracts data for the region: Longitude (-10 to 10) and Latitude (30 to 50)
9. Regridding to a Regular Grid
cdo remapbil,r360x180 input.nc regridded.ncRegrids the data to a 360×180 regular grid using bilinear interpolation
10. Calculating Anomalies
cdo sub input.nc climatology.nc anomalies.ncCalculates anomalies by subtracting the climatology from the input data
11. Concatenating Files
cdo cat file1.nc file2.nc concatenated.ncConcatenates multiple time steps from file1.nc and file2.nc into concatenated.nc
12. Removing Leap Years
cdo ydrunmin,365 input.nc noleap.ncRemoves leap days from the dataset
13. Computing Standard Deviation
cdo timstd input.nc std.ncComputes the temporal standard deviation and saves to std.nc
14. Converting GRIB to NetCDF
cdo -f nc copy input.grb output.ncConverts a GRIB file to NetCDF format
15. Extracting Statistics
cdo outputtab,mean input.ncOutput:
Mean: 273.15
16. Detecting Missing Values
cdo infon input.ncChecks for missing values in the dataset
