[ncl-talk] ESMF_Regrid for Coarse to Fine Spatial Resolution, two errors

[Greg Deemer]

Hello, 

I’m attempting to regrid sea-ice concentrations from a coarse spatial resolution onto a higher-resolution grid. Both grids are NSIDC Sea Ice Polar Stereographic North with a WGS84 reference datum. The coarse product (https://nsidc.org/data/g02202) is 448X304, or a 25km nominal resolution. The higher-resolution product (http://nsidc.org/data/docs/noaa/g02186_masie/index.html) is 6144x6144, or a 4km nominal resolution.

The grid for the high-res product is a little funky in that it extends well beyond the equator, from the polar view (for added context, it is the 4km variant of the 24km grid handled here: http://www.ncl.ucar.edu/Applications/nic_ims.shtml). I’m wondering if this is causing some error in the ESMF_regrid routine, which is throwing two errors:

1. nonsensical values to the minimum Extlon2d and minimum ExtGridCenter_Lon, as seen in the processing log

(0) get_src_grid_info: source lat dims = (448,304)
(0) get_src_grid_info: source lon dims = (448,304)
(0) get_src_grid_info: source grid type is 'curvilinear'
(0) curvilinear_to_SCRIP: calculating grid corners...
(0) curvilinear_to_SCRIP: no lat values are at the poles, so
(0)        calculating grid corners using
(0)        calc_SCRIP_corners_noboundaries...
(0) calc_SCRIP_corners_noboundaries
(0)      min/max original lat: 31.1026717524309/89.8368159996152
(0)      min/max original lon: -180/179.813975395493
(0) calc_SCRIP_corners_noboundaries
(0)      min/max Extlat2d: 30.8580632088782/89.8368159996152
(0)      min/max Extlon2d: -539.812759557033/180.001207917857
(0) calc_SCRIP_corners_noboundaries
(0)      min/max ExtGridCenter_lat: 30.98047461780758/89.8368159996152
(0)      min/max ExtGridCenter_lon: -269.812759557033/179.8151793919093
(0) =====> CPU Elapsed Time: curvilinear_to_SCRIP: 0.109368 seconds <=====
(0) get_dst_grid_info: destination lat dims = (6144,6144)
(0) get_dst_grid_info: destination lon dims = (6144,6144)
(0) curvilinear_to_SCRIP: calculating grid corners...
(0) curvilinear_to_SCRIP: no lat values are at the poles, so
(0)        calculating grid corners using
(0)        calc_SCRIP_corners_noboundaries...
(0) calc_SCRIP_corners_noboundaries
(0)      min/max original lat: -21.4848/89.9729
(0)      min/max original lon: -180/180
(0) calc_SCRIP_corners_noboundaries
(0)      min/max Extlat2d: -21.5023/89.9729
(0)      min/max Extlon2d: -539.995/180
(0) calc_SCRIP_corners_noboundaries
(0)      min/max ExtGridCenter_lat: -21.4935/89.9729
(0)      min/max ExtGridCenter_lon: -269.988/179.989

And a second error:
2. NetCDF: One or more variable sizes violate format constraints

I tried converting  longitudes to monotonic, but the output log still spit out large negative values (e.g. <<0). I’ve also added Opt at srcLargeFile and Opt at dstLargFile lines within the code as I see the resulting ‘destination-grid-file.nc’ is on the order of 3.15Gb in size.

Please find script attached. The data files in use for this script can be found here:
Coarse: ftp://sidads.colorado.edu/pub/DATASETS/NOAA/G02202_v2/north/daily/2006/seaice_conc_daily_nh_f13_20060101_v02r00.nc
Fine: ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/ancillary/masiemask_ims4km.nc

Thank you for the attention to this question and for any help.

-- 

Greg Deemer
User Services Office
National Snow and Ice Data Center
(303) 735-8068
http://nsidc.org
Twitter: @NSIDC

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