We have data from 1979-2015, which consists of various parameters like temperature etc. we need to create seasonal data i.e. say for summer jan-feb-march for all years i.e. separately for 1979, then jan-feb-march for 1980 etc. i.e in one file we want 111 months.
First of all how to achieve this ?
After that how to achieve the seasonal average of the same data above ?
thanks