Reformatting files to AeroCom/HTAP standards

Note: these commands cover the elder phase 3 naming scheme, but should nevertheless still usefull

The AeroCom standard is described in the section “submitting to the AeroCom database”.

Below simple nco commands are listed which can be of help to reformat.

A public set of format correction tools is under development and can be accessed here:

How to remind me of nco commands

Just type the command without arguments on a command line

How to rename variables

 ncrename -v oldvar,newvar

How to add an attribute

 ncatted -a experiment,newvar,a,c,"BASE"

Split files per variable

 cdo splitname

rename dimension

 ncrename -O -d LATITUDE,y       


 ncap2 -O -s "LOAD_BCPOM[time,x,y]=LOAD_BC+LOAD_POM" ${file} ${file} 

compute vertical integrals

 ncwa -O -v AERH2O3D_AER   -a z -y ttl     ${file}  
 ncrename -O -v AERH2O3D_AER,AERH2O_AER 
 ncks -F -A -v AERH2O_AER ${file} 

add variable to file

 ncks -F -A -v AIRE ${file}

make the time dimension unlimited

 ncecat -O $file $file
 ncpdq -O -a time,record $file $file
 ncwa -O -a record $file $file
 ncpdq -O -a time,y,x $file $file

turn z

 ncpdq -O -a -z $file $file

create yearly mean file

from 12 months in one file

 ncwa -F -O -a time ${file} ${orgfile}

calculate yearly average

fom 12 files each containing 1 month

 ncra -F -O  modis_2000??.nc ${yearfile}

create record dimension

 ncecat -O $file $file 

delete useless record dimension

 ncwa -O -a record $file $file 

turn lat to have right order

with interpolated files

 ncpdq -O -a "-y" $file $file 

Shift left and right hemispheres
 ncks -h -F -O -d x,1,180 $file $file1
 ncks -h -F -O -d x,181,360 $file $file2
 ncap -O -s "x[x]=x-360" $file2 $file2
 ncrcat -O $file2 $file1 $file
\rm  $file1 $file2

Similar reorder of longitude

ncecat -O $file $file 
ncpdq -O -a x,record $file $file 
ncwa -O -a record $file $file 
ncks -F -O -d x,1,180 $file $file1
ncks -F -O -d x,181,360 $file $file2
ncap -O -s "x[x]=x-360" $file2 $file2

ncrcat -O $file2 $file1 $file
\rm  $file1 $file2	
ncpdq -O -a time,y,x $file $file 

missing values

ncatted -O -a missing_value,$var,o,f,0 ${file} 
ncatted -O -a missing_value,$var,o,f,-9999 ${file} 

actually better use attribute _FillValue (see

compute monthly mean files

  for IMTH in ${MTH[*]} ; do 
ncra -F -O  ${file} ${filemean}

delete attributes

  ncatted -O -a ,,d,,
  ncatted -h -a ,global,d,,
  ncatted -h -a missing_value,,d,,