[ncl-talk] netcdf file compression

[Douglas Lowe]

Dear all,

I’m trying to use the file compression option listed on this manual page:
https://www.ncl.ucar.edu/Document/Functions/Built-in/setfileoption.shtml

This is my code:
file_chem   = addfile(filename+”.nc", "w")
setfileoption(file_chem,"Format","NetCDF4")
setfileoption(file_chem,"CompressionLevel",4)

However, I am not finding that there’s any extra compression of the data compared to
using the default compression level - and if I compress the file myself using nccopy
I find I can greatly compress the file (5Mb down to 50kb).

Have I missed any extra code that I should be adding (my variable processing / writing
code is the same as I’d use for netcdf3 files) to make this compression work?

thanks,
Doug