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

[Mary Haley]

Lin,

I think you need to set your SrcGridMask option. I noticed you had it
commented out:

    ;Opt at SrcGridMask      = where(.not.ismissing(y(0,:,:)),1,0)


If y contains missing values, then you need to set SrcGridMask. If y
contains missing values in the same location for every leftmost element of
y (assuming it's 3D), then what you have above should work, but you need to
uncomment it.

--Mary



On Mon, Jan 23, 2017 at 12:49 AM, 林祥 <xianglin72 at icloud.com> wrote:

> Hi,all
>
>
>          I am regriding some NSIDC sic data (http://nsidc.org/data/g02202.
> html, downloaded from 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/)
>
> 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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