Handling NetCDF

1. See data

ncdump -h or -c  #see the dimension and data info

2. Manipulating data
Extract data by timestep

cdo -O seltimestep,1,32,61 in.nc out.nc #extract the timestep 1, 32, and 61 from in.nc

Extract data by variable

cdo -O selname,storage in.nc out.nc #extract the storage variable

or

ncks -A -v storage in.nc out.nc

Delete data by timestep

cdo -O delete,timestep=13 temp.nc temp1.nc # delete the 13th time frame

Rename a variable

ncrename -v OldVarName,NewVarName in.nc #change variable name

3. Math
Add/subtract/multiply/divide two nc files

cdo -O add/sub/mul/div in1.nc in2.nc out.nc #add two nc files and output

Multiply by a constant (e.g. 0)

cdo -O mulc,0 in1.nc out.nc

Create new variable by adding others

ncap -O -s "storage=SoilMoist_1+SoilMoist_2+SoilMoist_3+SWE" in.nc out.nc #add all storage terms together and create a new variable "storage"
or
cdo expr,'runoff=srfrun+subrun;' in.nc out.nc

Add the field

cdo -O fldsum in.nc out.nc #add the value at each field

4. I/O
Output to ascii

cdo output in.nc > out.txt

5. ncview
Output frame as .png file when using ncview

 ncview -frame in.nc
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