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

[Mary Haley]

In order to properly debug this, I would need to have your script and data.
Can you provide this?

You can email me offline about this if you need to.

Thanks,

--Mary


On Mon, Jan 23, 2017 at 4:57 PM, 林祥 <xianglin72 at icloud.com> wrote:

> Mary,
>
>     Thank you for the reply! I’ve tried uncommenting the Opt at SrcGridMask
> before  with the following 2 lines
>
>      Opt at SrcGridMask      = where(.not.ismissing(y(0,:,:)),1,0)
>      Opt at DstGridMask      = where(.not.ismissing(hsic(0,:,:)),1,0)
>
>   and the output is as the attached plot file.   You can see that the land
> grid have been masked, but the ocean grids after regridding
>
>  are still  inconsistent with the original source grids ( the grids
> outside 90W-90E are different with the source grids) .
>
>    Besides, I found same problem occurred when I use the “bilinear” and
> “patch” method. But the combination of using “neareststod”
>
> method and uncommenting the above 2 lines seem produce the correct results
> ( see anther attached files). But I still feel puzzled.
>
>
> Thanks
>
>
> Lin
>
>
>
>
>
>
>
> 在 2017年1月24日，02:09，Mary Haley <haley at ucar.edu> 写道：
>
> 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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