#!/bin/sh -evx 

YEAR1=1995
YEARN=2005
IDIR=/cluster/shared/noresm/inputdata/atm/cam/volc
WDIR=/cluster/work/users/$USER
IFILE=CMIP_CAM6_radiation_v3_reformatted.nc
OFILE=`basename $IFILE .nc`_${YEAR1}-${YEARN}clim.nc 

cd $WDIR

# loop over calendar month 
for MM in `seq -w 01 12`
do 

  # estimate first and last record (add 1 extra because file starts dec 1849)
  REC1=`expr \( $YEAR1 - 1850 \) \* 12 + 1 + $MM`
  RECN=`expr \( $YEARN - 1850 \) \* 12 + 1 + $MM`

  # compute average for calendar month 
  ncra -h -F -O -d time,$REC1,$RECN,12 $IDIR/$IFILE tmp${MM}.nc

# end loop over month
done 

# concatenate months 
ls tmp??.nc | ncrcat -h -O -o $IDIR/$OFILE