[gradsusr] Standard deviation of an area

[Sourabh Bal]

Hello David and Julio,

if I want to plot time-latitude cross section (Y and T varying), with the
data being averaged over longitude (120 to 180), where shall I fix the
longitude.

set lat -90 90
set lon ??????
set t 1 21
d tloop(ave(aprl,lon=120,lon=180))


Sourabh



On Thu, Nov 20, 2014 at 1:35 AM, Julio Martinez <julioms24 at hotmail.com>
wrote:

> *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 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 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+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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>


-- 
Dr. Sourabh Bal
Post-Doc Fellow
Institute of Meteorology, Freie Universitat, Berlin
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