[gradsusr] Standard deviation of an area

[David Nielsen]

Hi, Julio,

My problem is not with the loop in time. I am using a "While" sintax to
execute the average along the series:

while (count < "number of t-values +1")
   'set t 'count
   'define average=aave(sst,x=127.8,x=128.6,y=27.6,y=28.6)'
   'd average'
   average=subwrd(result,4)
   rc = write ("c:\path\file.txt",average)
   count=count+1
endwhile

This is working fine. What I need now, is a way to calculate the standard
deviation of SST in the area of interest, also for each value of t, like
something independent of time, for me to insert inside the loop.

Everything Ive seen before is a standard deviation of the whole series
(like below), and not for each time-value.

'define sdsst=sqrt(ave(pow(ave(sst,t=1,t=12)-sst,2),t=1,t=12))' ->
calculates std of the series between t=1 and t=2. What I'd like to do is,
for each t, an std of the area.

Any suggestions?

Thanks!


On 19 November 2014 13:38, Julio Martinez <julioms24 at hotmail.com> wrote:

> *Hi David,*
>
>
> *I think you could try with tloop command...*
>
> Julio N. Martínez Sánchez
> M.C. en Oceanografía Física
> Consultor en Sitio
> Subgerencia de Pronóstico a Mediano y Largo Plazo
> Gerencia de Meteorología y Climatología
> Servicio Meteorológico Nacional
> Ext. 3156
>
>
> ------------------------------
> From: davidnielsen at id.uff.br
> Date: Wed, 19 Nov 2014 13:12:34 -0200
> To: gradsusr at gradsusr.org
> Subject: [gradsusr] Standard deviation of an area
>
>
> Dear all grads users,
>
> I would like to calculate the standard deviation of an area in Grads.
>
> I have a NetCDF wekly time series of SST (attached), and I am able to
> calculate the average of a certain area (defining LAT and LON) value using
> the "aave" formula, for each value of time, and generate a new series - ok.
> In addition to this seires, I would like to generate a series of standard
> deviations of this average, also for each time in the series. In other
> words, I need to to know, for a given area and time, what is the standard
> deviation of my variable?
>
> Please find attached an example of a NetCDF file I want to treat this way:
> 1. Calculate average of SST in a certain area (lat, lon) using aave, for
> each time value
> 2. Calculate standard deviation of SST in a certain area (lat, lon), for
> each time value
>
> Would anybody have any kind suggestions on how to address this #2 task?
>
> Many thanks in advance,
>
>
>
> --
> David Marcolino Nielsen
> Engenharia de Recursos Hídricos e do Meio Ambiente
> Universidade Federal Fluminense
> davidnielsen at id.uff.br
>
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-- 
David Marcolino Nielsen
Engenharia de Recursos Hídricos e do Meio Ambiente
Universidade Federal Fluminense
davidnielsen at id.uff.br
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