[gradsusr] ctl file for irregular lon and lat dimension

wendi harjupa wendiharjupa at gmail.com
Thu Jun 20 21:03:53 EDT 2019


Dear Mr. Jeff,

Thank you very much for your response.

I am very sorry for more question,
Would you mind to give me an example for your explanation?
or it ever asked before by other members, would you share me the link?

Best regards,
wendi

On Fri, Jun 21, 2019 at 2:27 AM Jeff Duda <jeffduda319 at gmail.com> wrote:

> Keep in mind that it's generally a good idea (but is not strictly
> required) that the following relationship is held in the XDEF and YDEF
> lines:
>
> max_x = min_x + dx*nx
> max_y = min_y + dy*ny
>
> What I usually do is find the maximum and minimum latitudes and longitudes
> anywhere in the geographic domain and then divide the difference in those
> by whatever you set for NX or NY. Use that as the step value. XDEF and YDEF
> are largely cosmetic for irregular grids, though. What is most important
> for getting your data to show up correctly is having a PDEF entry with the
> correct values for whatever your projection is. If your data are not
> projected in a way that Grads can support then I'm not sure you can do this
> using GrADS.
>
> Jeff Duda
>
> On Thu, Jun 20, 2019 at 1:46 AM wendi harjupa <wendiharjupa at gmail.com>
> wrote:
>
>> Dear GrADS users,
>>
>> I need your help with this problem.
>> I have two-dimensional data, which have no linear resolution, such below;
>>
>> 1. The first, second, third and the last coordinate longitude data are
>> 21.2887,  121.29860, 121.30840 and 148.76140, respectively.
>> 2. The first, second, third and the last coordinate latitude data are
>> 22.70906, 22.70909, 22.70911 and
>> 46.19549, respectively.
>>
>> I want to make the control file for the data to plot it by grads,
>>
>> XDEF LEVEL 2800 121.28870  XXXX
>> YDEF LEVEL 2400 22.70906 YYYY
>>
>> What number should I use to change XXXX and YYYY?
>> and is there special command should I use to handle the irregular spatial
>> resolution?
>>
>> Very appreciate for your help.
>> Thank you very much.
>> Best regards,
>> wendi
>>
>>
>>
>>
>> On Wed, Jun 19, 2019 at 9:17 PM wendi harjupa <wendiharjupa at gmail.com>
>> wrote:
>>
>>> Dear GrADS user,
>>>
>>> I want to plot the data which has irregular lon and lat...
>>> I donot want to interpolate the data, so I just want to plot it as the
>>> original data.
>>>
>>> My question is how to make the control file for the irregular lon and
>>> lat data.
>>> I attach two data through this email,
>>> 1. asci data which shows the different of lon and lat of the data.
>>> 2. Binary format data of the asci data.
>>>
>>> Thank you very much for your help.
>>>
>>> best regards
>>> wendi
>>>  RDCA20150803_0305.bin
>>> <https://drive.google.com/file/d/1HDCQXO30JwIRCaxTL-H1pf6eibRvhTpp/view?usp=drive_web>
>>>  RDCA20150803_0305.txt
>>> <https://drive.google.com/file/d/1l0vSZLO0Z21aBlfuMLF2UJM02m0kXTtC/view?usp=drive_web>
>>>
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>>
>
>
> --
> Jeff Duda, Research Scientist
> University of Colorado Boulder
> Cooperative Institute for Research in Environmental Sciences
> NOAA/OAR/ESRL/Global Systems Division
> Boulder, CO
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> gradsusr at gradsusr.org
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>
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