Re: Problem when doing area average....

Hi Sebi,
You should always look at your data before starting to analyze it. If you
look at your printVarSummary, you can see that the longitudes go from
-180:180. On your first area-average attempt, you referred to an area from
200:270E, outside your range of longitude values. (Hence the error
message.) The Nino3 region is entirely within your range of longitudes
when you specify it from -160:-90.

In order to calculate the Nino4 region, you need to flip the longitudes of
your data. The easiest way to do this is to use the function lonFlip:
http://www.ncl.ucar.edu/Document/Functions/Contributed/lonFlip.shtml

Finally, it is good practice to use cosine or gaussian weighting when
doing an area average. See example 1 of the wgt_areaave page here:
http://www.ncl.ucar.edu/Document/Functions/Built-in/wgt_areaave.shtml
Good luck,
Adam

> Hello ncl users,
> I want to do the area average for NINO3(5S-5N, 160W-90W) and
> NINO4(5S-5N,160E,150W) region.
> My data is in time,lat,lon order..
> when I use the following line for NINO3 area average
> NINO3=wgt_areaave(sstflt(:,{-5:5},{200:270}),1.0,1.0,0)
> I am getting the following error.
>
> fatal:NclOneDValGetRangeIndex: start coordinate index out of range, can't
> continue
> fatal:Could not obtain coordinate indexes, unable to perform subscript
> fatal:Execute: Error occurred at or near line 16 in file test.ncl
>
> So I changed my script like as follows...
> NINO3=wgt_areaave(sstflt(:,{-5:5},{-160:-90}),1.0,1.0,0)
> Then I am getting NINO3 correctly.
> But when I calculate for NINO4 as above i.e
> .NINO4=wgt_areaave(sstflt(:,{-5:5},{160:-150}),1.0,1.0,0) it is not
> averaging the desired region.It is averaging the other side(Not NINO4
> region).
> How I can found area average for NINO4 region..?
> .
> The print VarSummary of 'lon' is given below....
> Variable: lon
> Type: float
> Total Size: 1440 bytes
> 360 values
> Number of Dimensions: 1
> Dimensions and sizes: [lon | 360]
> Coordinates:
> lon: [-179.5..179.5]
> Number Of Attributes: 4
> long_name : Longitude
> standard_name : longitude
> units : degrees_east
> actual_range : ( -179.5, 179.5 )
>
>
>
>
> Also I am attaching the script ...
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> begin
> ;**************************************************************
> in2=addfile("/home/sebi/data/Had_sst/HadISST_sst.nc","r")
> sstflt=in2->sst(1308:1667,:,:)
> lon=in2->lon
> printVarSummary(lon)
> ;**************************************************************
> NINO3=wgt_areaave(sstflt(:,{-5:5},{-160:-90}),1.0,1.0,0)
> ; NINO3=wgt_areaave(sstflt(:,{-5:5},{200:270}),1.0,1.0,0)
> NINO4=wgt_areaave(sstflt(:,{-5:5},{160:-150}),1.0,1.0,0)
> ;********************************************************
> NINO3!0="time"
> NINO4!0="time"
> ;*******************************************************
> diro = "./"
> filo = "aaveged_JJAS_Hadsst_anom_1979_08.nc"
> system("/bin/rm -f "+diro+filo)
> f_select = addfile(diro+filo, "c")
> f_select->NINO3 = NINO3
> f_select->NINO4 = NINO4
> end
>
>
>
> Thanks in advance...
>
> --
> **********************************
> Sebi
> Climate and Global Modeling Division
> Indian Institute of Tropical Meteorology
> Pashan, Pune, 411 008
> ****************************************
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Received on Fri Feb 26 15:44:36 2010