[ncl-talk] Error in selecting box using coordinate subscripting

[Ushnanshu Dutta]

Dear Sir,
Are you working with SST data from CMIP5 and CMIP6? Except for a few models
, the SST data are provided on curvilinear grids.

The following page can be your help
https://www.ncl.ucar.edu/Applications/ESMF.shtml

I think through cdo "remapbil" regridding from curvilinear to rectilinear
(lon x lat) also possible. I have done that and compared with the original
one and found they are consistent. Can somebody comment on this?

On Mon, Jul 19, 2021 at 12:48 PM samirpokhrel via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Thanks Adam and Rashed,
>
>     Its confusing, As LonPivot is just re-arranging the the order of
> Longitude start and end point, but the basic range is similar to that of
> the models original grid (i.e -279 to 80).
> Is it not possible to arrange the longitudes in the way its easy i.e
> positive means east and negative means west longitudes.
> Is re-gridding data the only solution?
>
> regards
> Samir
> ------------------------------
> *From: *"Adam Phillips" <asphilli at ucar.edu>
> *To: *"samirpokhrel" <samir at tropmet.res.in>
> *Cc: *"ncl-talk" <ncl-talk at ucar.edu>
> *Sent: *Friday, July 16, 2021 11:21:32 PM
> *Subject: *Re: [ncl-talk] Error in selecting box using coordinate
> subscripting
>
> Rashed is right, lonPivot is definitely one way to get around this issue.
> Another possibility is to just specify the area like this:
> temp_et = temp({30:60},{-240:-170})
> Hope that helps!
> Adam
>
> On Fri, Jul 16, 2021 at 11:46 AM Rashed Mahmood via ncl-talk <
> ncl-talk at mailman.ucar.edu> wrote:
>
>> lonFlip assumes that the central longitude is either Greenwich meridian
>> (0) or 180 which is not the case in your data. Maybe "lonPivot" could do
>> the job?
>> https://www.ncl.ucar.edu/Document/Functions/Contributed/lonPivot.shtml
>>
>> Or regriding the data could be another option.
>>
>>
>>
>>
>>
>> On Fri, Jul 16, 2021 at 8:55 AM samirpokhrel via ncl-talk <
>> ncl-talk at mailman.ucar.edu> wrote:
>>
>>> Dear NCL Users,
>>>
>>>
>>> I am having problem while selecting a specific region within model
>>> output global data. Model data Longitudes varies from -279.75 to 79.75. The
>>> printVarSummary of the model data is as follows
>>>
>>> -------
>>>
>>> Variable: temp
>>>
>>> Type: double
>>>
>>> Number of Dimensions: 2
>>>
>>> Dimensions and sizes: [YT_OCEAN | 410] x [XT_OCEAN | 720]
>>>
>>> Coordinates:
>>>
>>> YT_OCEAN: [-80.75..89.75]
>>>
>>> XT_OCEAN: [-279.75..79.75]
>>>
>>> ---------
>>>
>>> When I am trying to Select the region 120 E to 170W and 30N to 60N by
>>> using coordinate subscripting viz.
>>>
>>>
>>> temp_et = temp({30:60},{120:-170})
>>>
>>>
>>> It is giving error like
>>>
>>>
>>> fatal:NclOneDValGetRangeIndex: start coordinate index out of range,
>>> can't continue
>>>
>>> fatal:Could not obtain coordinate indexes, unable to perform subscript
>>>
>>>
>>> Thereafter I have performed the lonFlip function
>>>
>>>
>>> temp_new = lonFlip(temp)
>>>
>>> temp_et = temp_new({30:60},{120:-170})
>>>
>>>
>>> and the error is solved and the printVarSummary now looks like
>>>
>>>
>>> ---------------------------
>>>
>>> Variable: temp_et
>>>
>>> Type: double
>>>
>>> Number of Dimensions: 2
>>>
>>> Dimensions and sizes: [YT_OCEAN | 40] x [XT_OCEAN | 440]
>>>
>>> Coordinates:
>>>
>>> YT_OCEAN: [30.2501..59.75]
>>>
>>> XT_OCEAN: [119.75..-99.75]
>>>
>>> ----------------------------
>>>
>>>
>>> This is incorrect as my data is 0.5 degree resolution and X dimension
>>> should be 140 size rather than 440 size
>>>
>>>
>>> Please let me know where I am going wrong
>>>
>>>
>>> Thanking you in advance
>>>
>>>
>>> Regards
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>
>
> --
> Adam Phillips
> Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
> www.cgd.ucar.edu/staff/asphilli/   303-497-1726
>
> <http://www.cgd.ucar.edu/staff/asphilli>
>
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-- 

*Ushnanshu Dutta*

*Research Fellow*

*Indian Institute of Tropical Meteorology*

*Pune,411008*
*Mob: 9405022799*
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