#!/bin/sh
for file in ACE_MAG_LV2_POLARIZATION_XYZ_HIRES_*.png
do
   year=${file:35:4}
   doy=${file:40:3}
   echo renaming $file to ACE_POLARIZATION_${year}_DOY_${doy}.png
   mv $file ACE_POLARIZATION_${year}_DOY_${doy}.png
done