[gradsusr] Averaging over multiple dimension ranges

[Ivan Toman]

Hello,

If I want to find average value over a lat/lon range, I would do:

ave(variable,lat=20,lat=21),lon=70,lon=71)


However, if I want to do average over multiple areas, for example:

Area 1: lat=20,lat=21 ; lon=60,lon=61
Area 2: lat=30,lat=31 ; lon=70,lon=71
Area 3: lat=40,lat=41 ; lon=80,lon=81

how can I solve this problem? I can't simply find three area averages, 
sum them together and divide by three, because areas are not the same sizes.

Thanks for any hint.

Regards,
Ivan Toman