Re: Regrid T62 data to POP grid

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Fri Nov 01 2013 - 09:11:51 MDT

Use NCL's ESMF regridding capabilities:
    http://www.ncl.ucar.edu/Applications/ESMF.shtml

**Please read the documentation.**

Specifically, you can use
 
http://www.ncl.ucar.edu/Document/Functions/ESMF/ESMF_regrid_with_weights.shtml

with the weight file below

---
Attached is a sample plot for a rectilinear grid (T62) to a POP grid.
The weight file is at:
   ftp ftp.cgd.ucar.edu
   anonymous
   email
   cd pub/shea/ESMF
   prompt
   get wgt.RL_T62_to_gx1v3.bilinear.nc
   quit
On 11/1/13 5:31 AM, Prasad, Siva wrote:
> I have used SCRIP to generate the weight file.
> When I used the conservative remapping as explained in
> http://www.cesm.ucar.edu/models/ocn-pop/scrip.shtml
>
> I got the following error ( still trying to figure out)
>
>
>   Using latitude bins to restrict search.
>    Computing remappings between: POP 3 Displaced-Pole T grid
>                             and  T62 Gaussian Grid
>   grid1 sweep
> STOP integration stalled: num_subseg exceeded limit
>
>
> Finally, I did a bilinear map method  which gave me incorrect values.
>
>
> Please let me know if I have chosen  the wrong method.
>
>
> Thanks
> Siva
>
>
> On Fri, Nov 1, 2013 at 1:20 AM, Mary Haley <haley@ucar.edu> wrote:
>
>> Prasad,
>>
>> Can you please be more specific about what you mean about the weight file
>> being wrong? Are you getting some kind of error message, or are the values
>> incorrect, or something else?
>>
>> --Mary
>>
>> On Oct 31, 2013, at 5:35 AM, "Prasad, Siva" <sp4436@mun.ca> wrote:
>>
>> Hi Dennis
>>
>> Thank you very much. I could resolve the error  with the suggested change.
>>
>> Unfortunately,  weightfile  seems to be wrong.
>>
>> Regards
>> Siva
>>
>>
>> On Wed, Oct 30, 2013 at 4:57 PM, Dennis Shea <shea@ucar.edu> wrote:
>>
>>> I am not sure about this but I speculate that the
>>> variable 'air' on the file is type short.
>>> It *must* be unscaled prior to use.
>>>
>>>    short air(time,lat,lon)
>>>    ^^^^^
>>>
>>> plus it will have associated attributes named:
>>> "add_offset" and "scale_factor"
>>>
>>> ===
>>>
>>> Try:
>>>
>>>    var = short2flt(f->air)
>>>
>>> http://www.ncl.ucar.edu/**Document/Functions/**
>>> Contributed/short2flt.shtml<http://www.ncl.ucar.edu/Document/Functions/Contributed/short2flt.shtml>
>>>
>>> ===
>>> The 1st rule of data processing is 'look at your data'.
>>>
>>> Please use the following to examimine file contents.
>>>
>>> %> ncdump -h air.2m.gauss.1997.nc | less
>>>
>>> or
>>>
>>> %> ncl_filedump air.2m.gauss.1997.nc | less
>>>
>>>
>>>
>>> On 10/30/13 11:48 AM, Prasad, Siva wrote:
>>>
>>>> Hi all,
>>>>
>>>> I am new to NCL. I  have generated a  weight file for T62
>>>> (map_T62_to_gx3_bilin_da_**301310.nc)
>>>>
>>>> I tried to use the following ncl script to remap to the POP but it shows
>>>> error
>>>>
>>>> load "$NCARG_ROOT/lib/ncarg/**nclscripts/csm/gsn_code.ncl"
>>>> load "$NCARG_ROOT/lib/ncarg/**nclscripts/csm/gsn_csm.ncl"
>>>> load "$NCARG_ROOT/lib/ncarg/**nclscripts/csm/contributed.**ncl"
>>>> load "$NCARG_ROOT/lib/ncarg/**nclscripts/csm/popRemap.ncl"
>>>>
>>>> a  = addfile("air.2m.gauss.1997.nc"**,"r")
>>>> var = a->air
>>>> remap = PopLatLon(var,"T62","gx3","**bilin","da","301310")
>>>>
>>>> out=addfile("t_10.nc","c")
>>>> filedimdef(out,"time",-1,True)
>>>> out->t10=remap
>>>>
>>>> I get the following error
>>>>
>>>> (0)
>>>> (0)    create_rmpPopFileName: ./map_T62_to_gx3_bilin_da_**301310.nc
>>>> fatal:pop_remap: dst_array must be of type float or double
>>>> fatal:["Execute.c":8128]:**Execute: Error occurred at or near line 462
>>>> in
>>>> file $NCARG_ROOT/lib/ncarg/**nclscripts/csm/popRemap.ncl
>>>>
>>>> fatal:["Execute.c":8128]:**Execute: Error occurred at or near line 642
>>>> in
>>>> file $NCAT
>>>>
>>>> Thanks and Regards
>>>> Nandu
>>>>
>>>>
>>>>
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>


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RL_T62_to_gx1v3.png
Received on Fri Nov 1 09:12:00 2013

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