CDO

for i in $(seq 1 6); do ls l${i}.nc; cp griddes griddes_${i}; perl -pi.bak -e "s/AAA/${i}/" griddes_${i} ; cdo -setzaxis,griddes_${i} l${i}.nc out${i}.nc ;done

cdo merge out{1,2,3,4,5,6}.nc OUT.nc