[gradsusr] Standard deviation of an area

[Julio Martinez]

David,
Maybe you could try with
d tloop(sqrt(pow(aave(uwnd,lon=200,lon=300,lat=0,lat=30),-uwnd,2)))


Julio N. Martínez Sánchez
M.C. en Oceanografía Física
Consultor en SitioSubgerencia de Pronóstico a Mediano y Largo PlazoGerencia de Meteorología y ClimatologíaServicio Meteorológico NacionalExt. 3156

From: davidnielsen at id.uff.br
Date: Wed, 19 Nov 2014 21:13:14 -0200
To: gradsusr at gradsusr.org
Subject: Re: [gradsusr] Standard deviation of an area

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+1endwhile
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 SitioSubgerencia de Pronóstico a Mediano y Largo PlazoGerencia de Meteorología y ClimatologíaServicio Meteorológico NacionalExt. 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 value2. 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 NielsenEngenharia de Recursos Hídricos e do Meio AmbienteUniversidade Federal Fluminensedavidnielsen at id.uff.br

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-- 
David Marcolino NielsenEngenharia de Recursos Hídricos e do Meio AmbienteUniversidade Federal Fluminensedavidnielsen at id.uff.br


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