THIS SCRIPT NEEDS THAT TWO VALID FILES
(WITH ONE TIME STEP EACH) ARE PLACED SOMEWHERE
WHICH CAN BE ACCESSED BY THE SCRIPT

FILENAME_PT NEEDS TO CONTAIN THE OUTPUT VARIABLES FROM
A PRODUCTION TAGGED AEROSOL RUN
filename_PT="/disk1/alfg/noresmrun/PTAER/PTAERO1_1YR_HR/PTAERO_10Mnth.nc"

FILENAME_MAM NEEDS TO CONTAIN THE OUTPUT VARIABLES FROM
A MAM3 AEROSOL RUN
filename_MAM="/disk1/alfg/noresmrun/PTAER/MAM3_1YR_HR/MAM3_10Mnth.nc"
