6/7/2019
Jim created soda3.12.2_mn_ocean_reg_2017.nc by:
cdo mergetime /aosc/greenland/soda3.12.2/REGRIDED/ocean/soda3.12.2_5dy_ocean_reg_2017*.nc temp.nc
cdo monavg temp.nc temp2.nc
cdo  selvar,temp,salt,wt,ssh,mlt,mlp,mls,net_heating,prho,u,v,taux,tauy temp2.nc soda3.12.2_mn_ocean_reg_2017.nc

After doing this I found that grads could not read  soda3.12.2_mn_ocean_reg_2017.nc.
I suspect the problem is an f32/f64 issue.  To get the right netcdf I used cdo mergtime followed by splityear:
cdo mergetime soda3.12.2_mn_ocean_reg_2016.nc soda3.12.2_mn_ocean_reg_2017.nc temp
cdo splityear temp soda3.12.2_mn_ocean_reg_
Now it seems to work.