CDO

Hi,
I have a file (sss.nc) with the following info:

dimensions:
x = 180 ;
y = 193 ;
time = 12 ;
variables:
double sss(time, y, x) ;
sss:missing_value = -99. ;
sss:units = "psu" ;
sss:long_name = "Sea surface salinity" ;

I want to add a field from another file (the sos variable from attached sos.nc) to this sss field. This file has the following info:
dimensions:

time = UNLIMITED ; // (12 currently)
    lon = 360 ;
    lat = 180 ;
variables:
    double time(time) ;
        time:standard_name = "time" ;
        time:long_name = "time" ;
        time:units = "months since 1-1-16 12:00:00" ;
        time:calendar = "365_day" ;
        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" ;
    float sos(time, lat, lon) ;
        sos:standard_name = "sea_water_salinity" ;
        sos:units = "psu" ;
        sos:_FillValue = 1.e+20f ;
        sos:missing_value = 1.e+20f ;
        sos:original_name = "so" ;

I see that some regridding is needed in order to add sos to sss. However, I do not have the target grid of the sss file. Therefore I do the following:
cdo setgrid,r180x193 sss_file_in.nc sss_file_out.nc # because this seems to be the grid, but I could be wrong
cdo remapbil,r180x193 sos_file_in.nc sos_file_out.nc

Now they should have the same grid characteristics, and I add the sos variable to the file with the sss variable (ncks -A -v sos sos_file_out.nc sss_file_out.nc). This is where I see the sss variable grid is shifted. I tried playing around with cdo shiftx and cdo sellonlatbox but to no good result.

Any ideas on how to handle this sss.nc file?

Thank you in advance,
Anne