[gradsusr] Find maximum at a point over a time period.

[Marsh, Kieren]

Thanks for your detailed response Davide, it's just what I was looking for.

Would you, or any other GrADS users know the server-side notation to do the same calculations as below?

I've never really got to grips with server-side notation, but in my case as I'm dealing with a fairly large data set on a remote server, the client side code below takes a while to come up with the final answer.

Thanks again
Kieren

-----Original Message-----
From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org] On Behalf Of Davide Sacchetti
Sent: 17 October 2012 13:41
To: GrADS Users Forum
Subject: Re: [gradsusr] Find maximum at a point over a time period.


suppose you fixed X and Y at your location
suppose you have 41 time steps (actually your are much more but it's the
same)

first question

        ga-> d max(t2,t=1,t=41)   
        MAXing.  dim = 3, start = 1, end = 41
        Result value = 295.123 
so you got max value

        ga-> d maxloc(t2,t=1,t=41)
        MAXLOCing.  dim = 3, start = 1, end = 41
        Result value = 19 
so you got when: maximum occured at t = 19


second question

suppose you want to find out how many times your T exceeded 292K (eg.: 5
times)
      * maskout(t2,t2-292) shows you only values > 292
      * const(maskout(t2,t2-292),1) shows you '1' only when values > 292
      * const(const(maskout(t2,t2-292),1),0,-u) shows you '1' only when
        values > 292, 0 otherwise
      * sum(const(const(maskout(t2,t2-292),1),0,-u),t=1,t=41) is your
        answer
        
        ga-> d sum(const(const(maskout(t2,t2-292),1),0,-u),t=1,t=41)
        SUMing.  dim = 3, start = 1, end = 41
        Result value = 5 
        
it should help ...
bye bye
Davide

On Wed, 2012-10-17 at 12:21 +0400, Marsh, Kieren wrote:
> Dear GrADS users
> 
>  
> 
> I have an hourly data set that spans about 7 months and I want to find
> the absolute maximum temperature at a given point and I also want to
> find out when that occurred.
> 
>  
> 
> Also is it possible to find the number of times the temperature
> exceeds a given value at a point and to find the corresponding times
> for each exceedence?
> 
>  
> 
> Can anyone, who has a better understanding of the max() function help
> me with this? I know the ordering of the nesting matters, but I’m not
> sure exactly how.
> 
>  
> 
> Thanks in advance.
> 
>  
> 
> Kieren
> 
>  
> 
> 
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
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-- 
--> Attenzione cambio indirizzo: davide.sacchetti at arpal.gov.it
--
Davide Sacchetti
Centro Funzionale Meteo Idrologico di Protezione Civile della Regione Liguria
ARPAL Unità Tecnica Complessa di livello Regionale
V.le Brigare Partigiane 2 16121 Genova (I)
tel: +39 010 6437535                    fax: +39 010 6437520
mail: davide.sacchetti at arpal.gov.it     web: www.meteoliguria.it


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