Project

General

Profile

Forums » Open discussion »

nc4 compression control

Added by Marston Ward almost 12 years ago

Hi,

I'm trying to create nc4 files from a grub conversion and I want to maximize the compression. What is the default compression and how do I modify that?

Appreciate your help,
/M


Replies (3)

RE: nc4 compression control - Added by Marston Ward almost 12 years ago

The above question should say grib, not grub. Damn autocorrect!

RE: nc4 compression control - Added by Etienne Tourigny almost 12 years ago

Hi,

My personal experience is that a deflate level of 6 is probably ok if you want to minimize size, with 2 it's much faster with only a 10% size penalty, and with 9 it's not really worth the (much longer) processing time.

Using the latest cdo version, do something like:

cdo -f nc4c -z zip_9 in.grib out.nc

from cdo -h:

     -z szip        SZIP compression of GRIB1 records
       jpeg        JPEG compression of GRIB2 records
        zip[_1-9]  Deflate compression of netCDF4 variables
    (1-3/3)