Hi Guoqing, I assume the NCL developers could make this setting available through their API. BTW, there are Fortran wrappers available for proj.4: https://github.com/mhagdorn/proj4-fortran or you could use a Fortran system call, or an NCL systemfunc call: https://www.ncl.ucar.edu/Document/Functions/Built-in/systemfunc.shtml Best, Craig