I am having a forcing NetCDF climatology file that has 4 dimensions, i.e. time, lat, long and lev. I am reading this file using Flexible Modelling System (FMS) from GFDL. I want to keep the time continuous, or something like a periodic boundary condition. For example, I should provide just one year monthly file, and the model should directly pick up the corresponding month from my file without exactly checking the specific year. I am performing some experiments in which some forcings are kept fixed and others changing (to provide a context why I want to do this).
You can use the following nco command to add modulo attribute to your time dimension
ncatted -a modulo,time,c,c," " filename.nc