Re: ttest and gsn_csm_pres_hgt

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Tue Jun 18 2013 - 08:46:29 MDT

@Ben: You should write to
       They may be able to offer suggestions.

Lena ...

There are aspects of the NCL script that confuse me.

[1] When you import a variable and then invert the grid via
     the ::-1 syntax, NCL is 'smart' about handling the
     associated coordinate meta data. Also, all meta data
     is 'private' to that variable. It is part of the variable's
     data structure. Look at the 'before' and 'after' ....
     Here the ::-1 reorders BOTH the array and the coordinate varialr
     to reflect the array reordering.

         aps_tmp = in->aps_ave ; TIME, LAT, LON
printVarSummary(aps_tmp) ; note the 'lat' coordinate variable
         aps = aps_tmp(:,::-1,:)
printVarSummary(aps_tmp) ; NCL has reordered the 'lat'

         U_wind_tmp = in->n->um1_avee ; TIME, LEV, LAT, LON
         U_wind = U_wind_tmp(:,:,::-1,:)

      Incidently, you can do the reorder without using a 'tmp' variable

          aps = in->aps_ave(:,::-1,:)
          U_wind = in->n->um1_ave(:,:,::-1,:)

[2] Generally there is no reason to explicitly read coordinate variable
     of a file.

         time_EMAC = in->time
         lat_EMAC = in->lat
         lon_EMAC = in->lon
         lev_EMAC = in->lev

    When you do
         U_wind_tmp = in->um1_ave
         aps_tmp = in->aps_ave

    each variable has its' own 'time'. Since they are from
    the same file, they are the same. Look at 'printVarSummary'

[3] When you do

          aps&lat = aps&lat(::-1)
          U_wind&lat = U_wind&lat(::-1)

     You have reordered the 'lat' coordinate variable BUT not the array
     with which it is associated. I would say this is incorrect.

[4] u_ave = dim_avg_n_Wrap(newgrid(:,:,::-1,:),0)

     I assume you are reordering to the N->S on purpose

I am at a mtg and must go ...

You can ftp the source file to

<use your email address for the password>
cd incoming
put ...


Send email to me after you have successfully completed the transfer.


On 6/18/13 7:02 AM, Lena Frey wrote:
> Hi,
> @Dennis: Please find attached my ncl script. Thank you.
> @Ben: Sorry, I don't know anyone who has used ECHAM5 to drive WRF.
> Lena
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Received on Tue Jun 18 08:46:29 2013

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