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

[Ushnanshu Dutta]

In continuation to my earlier email I forgot to mention the target grid
file. I have created the target grid file like this

cat > targetgrid << EOF
gridtype = lonlat
xsize    = 360
ysize    = 180
xfirst   = −179.5
xinc     = 1
yfirst   = -89.5
yinc     = 1
EOF


here you also have options to change the resolution.

On Mon, Jul 19, 2021 at 1:14 PM Ushnanshu Dutta <ushnanshudutta at gmail.com>
wrote:

> 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*
>


-- 

*Ushnanshu Dutta*

*Research Fellow*

*Indian Institute of Tropical Meteorology*

*Pune,411008*
*Mob: 9405022799*
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