CICE daily diagnostics

[Martin Dix]

Current CICE configurations, e.g. Peter's u-al623 have

histfreq='d','m','x','x','x'
histfreq_n=10,1,1,1,1

This seems to write files every 10 days which doesn't work well with the Gregorian calendar. E.g.

/short/p66/pbd562/archive/al623/history/ice/iceh.0001-01-10.nc
/short/p66/pbd562/archive/al623/history/ice/iceh.0001-01-20.nc
/short/p66/pbd562/archive/al623/history/ice/iceh.0001-01-30.nc
/short/p66/pbd562/archive/al623/history/ice/iceh.0001-02-09.nc
/short/p66/pbd562/archive/al623/history/ice/iceh.0001-02-19.nc

It also looks like many (all?) of the fields are 10 day means which don't seem very useful either.

[Martin Dix]

Siobhan and Arnold set up new CICE history configuration /short/p66/ars599/ACCESS-CM2/inputOM/cice/cice5.1.2_in.nml.spo599.31072018.

This was added to the CICE rose-suite.conf in the CABLE coupled suite u-bb194

[Martin Dix]

CICE is currently saving the daily diagnostics to a separate file for each day. E.g.,
iceh.0601-01-01.nc, … iceh.0601-01-31.nc with monthly means in iceh.0601-01.nc. The files are also netcdf classic format.

Converting the monthly to netCDF4 with nccopy reduces the size by a factor of about 6 (note that the -k 3 option actually specifies netCDF4!)

% nccopy -k 3 -d 4 iceh.0606-06.nc test.nc
% ls -l /short/p66/mrd599/archive/bf481/history/ice/iceh.0606-06.nc test.nc
-rw-r-----+ 1 mrd599 p66 68729268 Feb 25 08:41 iceh.0606-06.nc
-rw-r-----+ 1 mrd599 p66 10158755 Feb 25 12:09 test.nc

Adding the shuffle option actually increases the size slightly.

Using ncrcat from nco to combine the daily files gives a single file which is less than twice the size of a single day. This is largely because there is now only a single copy of the coordinate variables

% ncrcat -4 --deflate 4 iceh.0601-01-??.nc daily.nc
% ls -l iceh.0601-01-??.nc daily.nc
-rw-r-----  1 mrd599 p66 12980768 Feb 25 12:13 daily.nc
-rw-r-----+ 1 mrd599 p66  7349624 Feb 24 06:02 iceh.0601-01-01.nc

I create a new post-processing script ice_nc4.py to do this conversion, called from the filemove_access.sh script.

New output files are called iceh_m.DATE.nc and iceh_d.DATE.nc for monthly and daily data respectively.