Yes it is possible. The script will differ slightly depending upon what dimensions (XYZT) your data have and what type of variance you want to calculate (e.g. variance at each XY points etc. )
Anyway, here one sample command is given to start with:
Suppose your main variable is var of XYT dimension having daily data from 2001:2010. Then to find variance for each year (which will give 10 variance images having XY dimension each location of which represents variance for that location computed over all days of a year)
repeat/range=2001:2010/name=year (set region/t=1-jan-`year`:31-dec-`year`; let var_`year`=var[l=@var]; save/file=var_`year`.nc var_`year`;)
cancel region/T
This will save variance of each year to different nc files. This you can use later.
I hope this helps.
Regards,