[ferret_users] Mean seasonal cycle

["markus.mingel@xxxxxxxxx" <markus.mingel@xxxxxxxxx>]

Dear Users,

I am trying to compute the mean seasonal cycle for temperature in the period 
1961-1990 from a simulation covering a longer temporal period and I found some 
problems. I did the following:

! Define temporal window 1961-1990...
define axis/t=16-jan-1961:16-dec-1990:1/unit=months/edges/calendar=noleap 
month_noleap

! ...and keep only data in this period
let temperature_monthly  =               temperature[gt=month_noleap@asn] 


! Define the monthly time axis... 
def axis/T=01-JAN:"31-DEC:23:59:59"/npoints=12/modulo/calendar=noleap 
month_reg_noleap 

! ...and compute mean seasonal cycle
let tmp_monthly_cycle     =              temperature_monthly
[gt=month_reg_noleap@mod] 


However comparing results with the same results obtained forcing the variable 
with the time index (let temperature_monthly  =  temperature[l=X:Y] )  I see 
some differences.
Could anyone explain this difference?

Thanks into advance

Regards
Markus