There's an FAQ about making a seasonal mask,
How can I create a seasonal mask?
It uses similar ideas to what Paul suggests. The mask is always defined in terms of the definition of the time axis.
On 10/13/2011 2:10 AM, nuncio@xxxxxxxxx wrote:
Dear Ferreters I like to save all the JJA,SON,DJF values of a 30 year long time series of global SST to seperate files on to a continuous time axis. My data begins at 1980 january and ends at 2010 dec I need to save 30*3 values continuously, ie after I make each file, t axis must run from 1 to 90, with out bad values in between. Best regards nuncio Nuncio Murukesh, Ph.D Research Scientist. National Centre for Antarctic and Ocean Research Headland Sada, Vasco Da Gama Goa, 403804 India. Ph: Cell-91 9890357423 off- 91 832 2525428