CDO

Hi, I'm Changmook, a CDO user.

First, thank you for continuously providing convenient operators.
I'm having a problem that forced variable information to change when I use CDO for my data.

e.g.)
[my raw data's attribute]
$> ncdump -h test.nc

netcdf test {
dimensions:
time = UNLIMITED ; // (5 currently)
level = 20 ;
lat = 73 ;
lon = 144 ;
variables:
double time(time) ;
time:_FillValue = 9.96920996838687e+36 ;
time:original_name = "Lead Time of Forecast in months" ;
time:units = "days since 1900-01-01" ;
time:calendar = "standard" ;

• int level(level) ;*
  level:original_units = "Ensemble Member (no units)" ;
  level:units = "m" ;
  level:original_name = "Ensemble Members" ;
  float lat(lat) ;
  lat:nlat = 73 ;
  lat:long_name = "latitude" ;
  lat:units = "degrees_north" ;
  float lon(lon) ;
  lon:nlon = 144 ;
  lon:long_name = "longitude" ;
  lon:units = "degrees_east" ;
  float t2m(time, level, lat, lon) ;
  t2m:long_name = "Temperature at 2m" ;
  t2m:units = "deg K" ;
  t2m:missing_value = 1.e+20f ;
  t2m:_FillValue = 1.e+20f ;

// global attributes:
:creation_date = "Fri Mar 20 17:29:27 KST 2020" ;
:Conventions = "None" ;
:title = "Written using AFS function write_TLLL" ;
:institute = "CMCC" ;
:model = "SPS3" ;
}

When using CDO !! (CDO version 1.9.8)
$> cdo copy test.nc test2.nc
$> ncdump -h test2.nc

netcdf test2 {
dimensions:
time = UNLIMITED ; // (5 currently)
lon = 144 ;
lat = 73 ;
level = 20 ;
variables:
double time(time) ;
time:standard_name = "time" ;
time:units = "days since 1900-01-01" ;
time:calendar = "standard" ;
time:axis = "T" ;
float lon(lon) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude" ;
lon:units = "degrees_east" ;
lon:axis = "X" ;
float lat(lat) ;
lat:standard_name = "latitude" ;
lat:long_name = "latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;

• double level(level) ;*
  level:units = "m" ;
  level:axis = "Z" ;
  level:original_units = "Ensemble Member (no units)" ;
  level:original_name = "Ensemble Members" ;
  float t2m(time, level, lat, lon) ;
  t2m:long_name = "Temperature at 2m" ;
  t2m:units = "deg K" ;
  t2m:_FillValue = 1.e+20f ;
  t2m:missing_value = 1.e+20f ;

// global attributes:
:CDI = "Climate Data Interface version 1.9.8 (https://mpimet.mpg.de/cdi)" ;
:Conventions = "None" ;
:history = "Thu Feb 04 20:10:07 2021: cdo copy test.nc test2.nc" ;
:creation_date = "Fri Mar 20 17:29:27 KST 2020" ;
:title = "Written using AFS function write_TLLL" ;
:institute = "CMCC" ;
:model = "SPS3" ;
:CDO = "Climate Data Operators version 1.9.8 (https://mpimet.mpg.de/cdo)" ;
}

The variable information is changed (integer to double) as above.

Is there any way to use CDO operator without changing the variable information?
Or.. is there a operator (using CDO) that can change the level information back to integer?

help me plz...