Opened 10 years ago

Closed 10 years ago

#624 closed help (fixed)

Regridding N96 ancils to N48

Reported by: ata27 Owned by: jeff
Component: UM Model Keywords: gridding, N48, N96
Cc: Platform:
UM Version: 7.3


I am trying to regrid a set of ancils from N96 to N48. I have a problem with things like sea ice which has "missing values" over land. When I do the regridding using convsh I get odd looking edge effects. Is there a way of incorporating the N48 land sea mask so as to sort out this problem? Or will that make things worse? Any help would be appreciated!


Change History (6)

comment:1 Changed 10 years ago by jeff

  • Owner changed from um_support to jeff
  • Status changed from new to accepted

Hi Alex

Are you planning on using xancil to convert the file back into ancil format?

If so this method should work, use the extrapolate over missing data option first then interpolate to n48. Then when you use xancil use the n48 land sea mask to create sea only data.

In convsh the command to use extrapolate is

extrap $field 2

2 is the minimum number of nearest neighbours and can have the values 1-4.


comment:2 Changed 10 years ago by ata27

Hi Jeff,

Thanks for the help!!


comment:3 Changed 10 years ago by ata27

Hi Jeff,

So I have done the extrap and interp in xconv/convsh and have now opened up the ncdf file in xancil. (t

When I go to make it as a Sea Ice ancillary I dont seem to be able to select either tab with the options:

"Use land…NetCDF file to calculate land mask"

When I look at the output file it is exactly the same as the ncdf..

My input file is on hector:

This doesnt look right to me. I guess I am doing something wrong but I'm not sure what. Any help appreciated!



comment:4 Changed 10 years ago by jeff

Hi Alex

I don't have permission to read your files.

In order to select the land-sea mask file option you need to go to the Land/Sea? Mask panel and select yes for "Use Land/Sea? mask NetCDF variable?", then fill in the details.


comment:5 Changed 10 years ago by ata27

Hi Jeff,

Ahh.. right OK then, that clears that all up.



comment:6 Changed 10 years ago by jeff

  • Resolution set to fixed
  • Status changed from accepted to closed
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