Re: [ferret_users] Mean seasonal cycle

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

HI-
The first thing that comes to my mind is to look at the @ASN 
transformation that you use in the variable temperature_monthly.  Is the 
original data monthly data which starts in January 1961? @ASN does not 
take the original dates into account but puts the data onto the new axis 
starting with the first value.  If the data does not start in Jan 1961 
then you would see a shift in the data by using @ASN.

-Ansley

On 1/26/2012 9:08 AM, markus.mingel@xxxxxxxxx wrote:
> 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