Directories storing model output

1. Run directory: /cluster/work/users/<username>/noresm/cases/$CASE (on Fram/Betzy)
2. Short-term archive: /cluster/work/users/<username>/archive/cases/$CASE (on Fram/Betzy).
   NOTE, files older than 21 days might be automatic deleted (see Fram/Betzy documentation)
3. Medium/Long-term archive: should archive the data to the NIRD project areas, e.g., /projects/NS2345K for INES project.

History File Naming Conventions

• All history output files are written in NetCDF-3 format, and automatically converted to compressed NetCDF-4 format (with tool noresm2netcdf4)
• Output of each component store seperately as <component>/hist, e.g, atm/hist ocn/hist, etc. Restart files are stored under rest/hist.

$ tree -L 2
.
├── archive.log.200921-151923
├── atm
│   └── hist
├── cpl
│   └── hist
├── esp
│   └── hist
├── ice
│   └── hist
├── lnd
│   └── hist
├── logs
│   ├── atm.log.781577.200921-144102.gz
│   ├── cesm.log.781577.200921-144102.gz
│   ├── cpl.log.781577.200921-144102.gz
│   ├── ice.log.781577.200921-144102.gz
│   ├── lnd.log.781577.200921-144102.gz
│   ├── ocn.log.781577.200921-144102.gz
│   └── rof.log.781577.200921-144102.gz
├── ocn
│   └── hist
├── rest
│   └── 0001-02-01-00000
└── rof
    └── hist

Example history file names:

• <compset name>_<resolution sname>_<opt_desc_string>_<component>.<frequency>_<date>.nc
• N1850frc2_f19_tn14_Workshop2021.blom.hm.0001-01.nc
• N1850frc2_f19_tn14_Workshop2021.cam.h0.0001-01.nc

By default, h0,hm denotes that the time sampling frequency is monthly. Other frequencies are saved under the h1, h2, etc.

Different time sampling frequencies have distinct tags in the file names.

A full list of the tags:

    - blom.hy    = blom yearly
    - blom.hbgcy = blom/bgc yearly
    - blom.hm    = blom monthly
    - blom.hbgcm = blom/bgc monthly
    - blom.hd    = blom daily
    - blom.hbgcd = blom/bgc daily
    - cice.h     = ice monthly
    - cice.h1    = ice daily
    - cam.h0     = cam monthly 
    - cam.h1     = cam daily
    - cam.h2     = cam 6-hourly average
    - cam.h3     = cam 6-hourly instant
    - cam.h4     = cam 3-hourly average
    - cam.h5     = cam 3-hourly instant
    - clm2.h4    = clm yearly
    - clm2.h0    = clm monthly
    - clm2.h1    = clm daily
    - clm2.h2    = clm 3-hourly average
    - clm2.h3    = clm 3-hourly instant

NorESM horizontal and vertical grid system

Horizontal grids

• NorESM1 (MICOM) for CMIP5: bipolar grid
• NorESM2 (BLOM) for CMIP6: tripolar grid

Vertical grids

• CAM: terrian-following sigma coordinate
• BLOM: isopycnic (potential density $\sigma_2$) coordinated vertical coordinate
• NorESM2 (BLOM) for CMIP6: tripolar grid

Challenges

• Regrid ocean tripolar grid to 1x1 degree grid
• Interpolate CAM terrian-following sigma coordinate to pressure levels
• interpolate BLOM isopycninc vertical coordinate to depth (z) levels

NorESM output time axis/variable

BLOM
The time coordinate variable in ocean model BLOM history represents the middle of the averaging period for variables that are averages. Notime_bounds for the time axis.

CAM
The time coordinate variable in atmospheric model CAM history and timeseries files represents the end of the averaging period for variables that are averages (inherited from CESM). Its time_bnds attribute of time axis gives over which period the field is averaged.

Example File: N1850frc2_f19_tn14_Workshop2020.cam.h0.0001-01.nc
When the time coordinate variable is translated, the time is 00Z Februray 1st 0001, even though the file holds averaged variables for January 0001.

BLOM output

$ ncdump -t -v time N1850frc2_f19_tn14_Workshop2020.blom.hm.0001-01.nc |tail -4
data:

 time = "0001-01-17" ;
}

CAM output

$ ncdump -t -v time N1850frc2_f19_tn14_Workshop2020.cam.h0.0001-01.nc |tail -5
		:time_period_freq = "month_1" ;
data:

 time = "0001-02-01" ;
}

$ ncdump -t -v time_bnds N1850frc2_f19_tn14_Workshop2020.cam.h0.0001-01.nc |tail -5
data:

 time_bnds =
  "0001-01-01", "0001-02-01" ;
}

Challenge

• Check the time-axis conventions in other components of NorESM (using your favorate tool)
• Check the time-axis of instantaneous output files, e.g, files with tags cam.h3,cam.h5, and clm2.h3 in the name.