[ncl-talk] Question on the "ESMF_regrid" when the longitude of source and destination grids is in different order?

[林祥]

Hi,all


         I am regriding some NSIDC sic data (http://nsidc.org/data/g02202.html <http://nsidc.org/data/g02202.html>, downloaded from ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02202_v2 <ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02202_v2>).

The source data is curvilinear grids with 2-d longitude coordinate array ranging  between -180E~180E， and the destination grids is HadISST 2.2 (http://www.metoffice.gov.uk/hadobs/hadisst2/ <http://www.metoffice.gov.uk/hadobs/hadisst2/>)

which is rectilinear grids ranging from 0E to 360E.  

         I try to use the original longitude of source grids with the following :

   fi     = addfile(data_path + data_filename,"r")
   lon    = fi->longitude
   lat    = fi->latitude  
 
   y at lat2d  = lat
   y at lon2d  = lon                     

    or reset the longitudes  to 0~360E using the following lines:
  
  lon      = where(lon.lt.0,lon+360,lon)     ; -180 ~ 180 longitude order
  lon at units= "degrees_east"
  
But I got the same result and the regridded data contain missing values outside the range of -90W~90E.Please see the attached plot file

I don’t know where the problem come from.  And I also found no instruction on the NCL webpages explaining the similar case when the curvilinear

grids share different longitude ranges with the destinate grids.  So anyone can show me a hand?


The script file, source data file , contour plot files with original data and regridded data have been attached.


Thanks!



Lin














         
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