[ferret_users] looking for an elegant way to regrid gridded netcdf with broken grid specs but with gridded lat/lon cell values

To: users Group Ferret <ferret_users@xxxxxxxx>
Subject: [ferret_users] looking for an elegant way to regrid gridded netcdf with broken grid specs but with gridded lat/lon cell values
From: Lev Tarasov <lev@xxxxxx>
Date: Tue, 24 Apr 2018 14:03:05 -0230 (NDT)
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This is unfortunately a too frequent problem at least for data sources I'musing. The source files tend to be on curvilinear grids (eg DEM, orobscure GCM/RCM grid or some other curvilinear projection) and theinternal net-cdf grid specs are broken so that simple regridding doesn'twork. However, the dat set includes grid-center lat and lon for

each grid cell (so on the same grid). Now I could do a bunch of repeat

loops, list to file in 1D format and then use scat2grid* and repeat forall the 20 fields * 12 months I want to extract, but I'm hoping

there's a much more elegant way to work directly with the netcdf file
(if not in ferret, then some other tool? (cdo remapbil doesn't work).
 
 
Eg, my current case:
 
yes? show dat
currently SET data sets:
1> ./MARv3.5.2-10km-monthly-ERA-Interim.yMonMeanClim19C.nc  (default)
LAT      Latitude                         1:301     1:561     ...       ...       ...       ...
LON      Longitude                        1:301     1:561     ...       ...       ...       ...
TT       3m-Temperature                   1:301     1:561     ...       1:12      ...       ...
and 20 other fields
 
 
yes? show grid tt
GRID GQA1
name       axis              # pts   start                end
X         LONGITUDE          301 r   5E                   65E(1505)
Y         LATITUDE           561 r   5N                   2805N
normal    Z
TIME      TIME                12 i   15-JAN-2000 00:08    14-DEC-2000 19:32
 
Even though this is actually a curvilinear projection (from readme)
grid_mapping_name,stereographic "Stereographic Oblique Projection"
standard_name,stereographic "Stereographic Oblique Projection"
long_name,stereographic "Stereographic Oblique Projection"
longitude_of_projection_origin 40°W
latitude_of_projection_origin 70.5°N
false_easting -775 km
false_northing -1200 km
resolution 25km
 
so standard regridding:
shade TT[g=GRf525, l=6]
gives a messed up plot
 
 
yes? show grid GRf525
GRID GRF525
name       axis              # pts   start                end
XLONGRF5  LONGITUDE          155mr   80.75W               3.75W
YLATGRF25 LATITUDE           105 r   58.875N              84.875N
 
 
Cheers,
 
Lev
 
 
Lev Tarasov -   Dept of Physics and Physical Oceanography,
		Memorial University of Newfoundland.
email: lev@xxxxxx
Re: [ferret_users] looking for an elegant way to regrid gridded netcdf with broken grid specs but with gridded lat/lon cell values
From: Ansley C. Manke






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