[ncl-talk] How to change the data on a rectilinear lat/lon gridto a curvilinear grid whithout changing its original resolution

[易路]

Thanks a lot for your detailed reply. My problem has been resolved  by seeting the resources of mpProjection and other related resources such as mpLambertParallel1F et.al.  to plot the TRMM data on a map which have the same projection of WRF output data. There is no need to use any funtions to regrid the TRMM data. Sorry for not expressing my problem well, but thank you very much all the same! 
 
Best regards!
 
Yi Lu
 






易路

南大邮件系统/学生/博士生/12级博士生

南京市汉口路22号 




 
 
 
------------------ Original ------------------
From:  "Dennis Shea"<shea at ucar.edu>;
Date:  Fri, Aug 19, 2016 02:10 AM
To:  "易路"<dg1225033 at smail.nju.edu.cn>; 

Subject:  Re: [ncl-talk] How to change the data on a rectilinear lat/lon gridto a curvilinear grid whithout changing its original resolution

 
Not sure what is meant by:
"So I doubt whether there is any other functions to  change the TRMM data  on a  rectilinear lat/lon grid to a curvilinear grid without changing  its original resolution?"


Short answer: There are no 'other functions.'
=====


In physical space on a sphere, each degree of latitude is approximately 111 km. The longitudes change as a function of the cosine(latitude). EG: at 40 degrees of latitude the longitudinal spacing is about 85km.


So ... a 0.25 grid at the equator is 0.25*111=27.75km while at 40 {S/N} latitude, it is 0.25*85=21.25km

===

Typically, a WRF file has two global attributes which specify the grid resolution, eg:

      DX : 10000    (meters)   10KM
      DY : 10000        

===

So, in the example, the 0.25 lat/lon grid contains information on a much coarser grid the the WRF grid. 


Interpolating the coarser TRMM grid to the same lat/lon coordinates of the WRF file will contain no *additional* information. 


Not sure if this answers your question.
     

---










On Thu, Aug 18, 2016 at 2:55 AM, 易路 <dg1225033 at smail.nju.edu.cn> wrote:
Hi all, 
  I would like to plot the TRMM 3B42 precipitation data (0.25 degree) on a map with the "Lambert Comformal" projection, so as to keep the same projection with the WRF output data. But when I used the funtions like rgrid2rcm or esmf_regrid, the resolution of the TRMM data changed from the original 0.25 degree to the resolution of WRF output data.
  So I doubt whether there is any other functions to  change the TRMM data on a  rectilinear lat/lon grid to a curvilinear grid whithout changing its original resolution?
 
Thanks a lot!
Best regards!






易路

南大邮件系统/学生/博士生/12级博士生

南京市汉口路22号 




 


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