# Re: How to make composite from 4 variables..................

From: Jessica Paxton <jnpaxton_at_nyahnyahspammersnyahnyah>
Date: Wed, 26 Aug 2009 11:18:55 -0600

Your approach looks fine.

What you may think about doing is combining a few steps to reduce memory:

sst= short2flt( in2->sst )

average = (SSTA_1983_JJAS+SSTA_1990_JJAS+SSTA_1999_JJAS+SSTA_2004_JJAS)/4
average_at_long_name = "JJAS: 1983,1990,1999,2004" ; optional
average_at_units = sst_at_units ; optional
copy_VarCoords( sst(0,:,:), average ) ; for netCDF or plotting
printVarSummary( average )
printMinMax(average, True)

In addition, using "dim_avg_Wrap" will help to preserve meta data, which
is useful for netCDF output or plotting. If you have version 5.1.1, you
should try using dim_avg_n_Wrap, which allows you to average without
dimension reordering.

Jess

Sabeerali(sebi) wrote:
> Hello,
>
> I have taken monthly sst from 1983-2005 and calculated
> monthly sst anomaly...From the total sst anomaly(i.e from 1983-2005) I
> selected 4 years(1983,1990,1999,2004) and found the average of JJAS...So
> I got 4 variables of dimension (lat=89,lon=180) (SSTA_1983_JJAS,
> SSTA_1990_JJAS, SSTA_1999_JJAS, SSTA_2004_JJAS)..I want to find the
> composite of these 4 variables..
> The given method is valid or not...
> sum= SSTA_1983_JJAS+SSTA_1990_JJAS+
> SSTA_1999_JJAS+SSTA_2004_JJAS
> average=sum/4
>
> .Any help would be appreciable...Here I am attaching the script..
>
>
> begin
> ;**************************************************************
> sst=in2->sst
> sstflt=short2flt(sst)
> ;printVarSummary(sst)
> mn_clim_sst=clmMonTLL(sstflt)
> ;printVarSummary(mn_clim_sst)
> ;printVarSummary(mn_clim_sst)
> Mon_sst_anom=calcMonAnomTLL(sstflt,mn_clim_sst)
> ;*****************************************************
> SSTA_1983=Mon_sst_anom(0:11,:,:)
> SSTA_1983_JJAS=dim_avg(SSTA_1983(lat|:,lon|:,time|5:8))
> ;**************************************************
> SSTA_1990=Mon_sst_anom(84:95,:,:)
> SSTA_1990_JJAS=dim_avg(SSTA_1990(lat|:,lon|:,time|5:8))
> ;**************************************************
> SSTA_1999=Mon_sst_anom(192:203,:,:)
> SSTA_1999_JJAS=dim_avg(SSTA_1999(lat|:,lon|:,time|5:8))
> ;********************************************************
>
>
>
>
> ------------------------------------------------------------------------
>
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```--
*********************************************************
Jessica N. Mackaro

Climate Analysis Section
Climate and Global Dynamics Division
National Center for Atmospheric Research
P.O. Box 3000
Boulder, CO 80307
tel: 303-497-1305   fax: 303-497-1333
email: jnpaxton_at_ucar.edu
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Received on Wed Aug 26 2009 - 11:18:55 MDT

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