CDO

Dear everybody,

I want to remap an emissions file (non-rotated) to my model grid (lat-lon rotated). So I use this cdo command:

cdo remapcon2,grid_rot_nmmb grid_tno_setgrid.nc test.nc

Where grid_rot_nmmb is:

gridtype = lonlat
xname = lon
yname = lat
xunits = degrees
yunits = degrees
xsize = 339
ysize = 309
xfirst = -33
xinc = 0.2
yfirst = -25
yinc = 0.2
xnpole = -169
ynpole = 44

After this remapping I compare the mass of my pollutants and change, so I suspect that this command: remapcon2 is not conservative:
3.51578e+06 > 2.55739e+06

Original emissions file:
cdo output -selvar,NOx -fldsum grid_tno_setgrid.nc
cdo output: Started child process "selvar,NOx -fldsum grid_tno_setgrid.nc (pipe1.1)".
cdo(2) selname: Started child process "fldsum grid_tno_setgrid.nc (pipe2.1)".
3.51578e+06

File after remapping in my model grid:
cdo output -selvar,NOx -fldsum test.nc
cdo output: Started child process "selvar,NOx -fldsum test_con_w.nc (pipe1.1)".
cdo(2) selname: Started child process "fldsum test_con_w.nc (pipe2.1)".
2.55739e+06

I am doing something wrong?

Thank you very much,

Alba