how to make two file's time consistent?

[dongdong]

  Hello everyone,
      I want to find relations of precipitation and 500mb pressure. Because they are from files with different serial and diffenent time stride, I didn't know how to adjust then. Any help will be greatly appreciated!

     precipitation is yearly,from1950 to 2000, however, pressure is monthly 1957.9.1 ~ 2002.8.1.
     I meant to calculate yearly pressure first, my script is:

  'open /chdd/work4/grads_used/pressure.ctl'
'set lat 0 90'
'set lev 500'
t=5
while(t<522)
   'set t ' t
   'define zyear=ave(Zprs,t=' t ',t=' t '+12,-b)'
   t=t+12
endwhile

  yet, It is wrong  Whenever I set time dimension, zyear always showing the same value. what's more, zyear have value even at times i didn't define. such as t=1 ( t=1 refer to 1957.9.1)

    Can you help me get averaged pressure at times consistent with precipitation, and use TCORR to find their space pattern?

  the two control files are in attachment.

  Thank you for your caring,May you all the best!!!




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