WEIGHTS produces bad values

Hello again.)

To initialize the model (global ORCA2), I use the global ocean analysis and forecast 1/12 degree data from CMEMS. There are no runtime errors when creating weights using the WEIGHTS tool from the dataset coordinate grid to the ORCA_R2_zps_domcfg coordinate grid (default from ORCA2_ICE_PISCES). However, when viewing the resulting interpolation weights, it’s found that in the variables wgt03 and wgt04 there is one value approximately 2160 and -2160, respectively. Although the interpolation weights should be within [0,1].
This effect is observed with map_method = [‘bilinear’,‘bicubic’] and with ew_wrap = [-1,0,1,2]. Coordinates of the point → 179.99992124 E, 0.0 N.
When calculating interpolation weights for forcing (global gfs data), no such effect is observed.
Illustrating weights maps and namelist_bilin are attached below.

All weights variables (lat=y, lon=x in ORCA grid)

 - grid_inputs holds parameters for the scripgrid routine which reformats information 
   about the input grids
 - scripgrid always needs a coordinates.nc file in the
   current directory and creates the remapped grid file correspondingly
 - it uses the following namelist block to determine its actions
     method:  only 'regular' is yet implemented, this assumes a cartesian grid
     input_lon: name of longitude variable in the input_file
     input_lat: name of latitude variable in the input_file
     nemo_lon: name of longitude variable in the coordinates.nc
     nemo_lat: name of latitude variable in the coordinates.nc
    input_file = 'gl12_mean_20230130_R20230201.nc'
    nemo_file = 'ORCA_R2_zps_domcfg.nc'
    datagrid_file = 'remap_glorys_grid.nc'
    nemogrid_file = 'remap_ORCA2_grid.nc'
    method = 'regular'
    input_lon = 'longitude'
    input_lat = 'latitude'
    nemo_lon = 'glamt'
    nemo_lat = 'gphit'
    nemo_mask = 'none'
    nemo_mask_value = 10
    input_mask = 'none'
    input_mask_value = 10
 - remap_inputs holds parameters for the scrip routine which calculates the weights
   needed to convert between two grids
 - two remap grid files are required as output by scripgrid
 - num_maps is either 1 or 2 depending on whether the reverse transformation is required
 - one or two interp_file names are then supplied; these hold the weights to convert 
   one grid to another
 - the map_name variable is just descriptive
 - map_method can be 'bilinear' 'bicubic' or 'conservative' (the latter untested)
 - normalize_opt should usually be 'frac' or else the user needs to do this scaling
   manually (this seems to the case for fractional ice cover)
 - restrict_type should be 'latitude' or 'latlon' in which case num_srch_bins only are 
   used in one or two directions
 - use_grid_area fields override the scrip calculation of area in case the model gets
   slightly different answers, but the area needs to be supplied in the input files
 - output_opt may be supplied and set to either 'scrip' or 'ncar-csm'
    num_maps = 1
    grid1_file = 'remap_glorys_grid.nc'
    grid2_file = 'remap_ORCA2_grid.nc'
    interp_file1 = 'glorys_ORCA2_bilin.nc'
    interp_file2 = 'ORCA2_glorys_bilin.nc'
    map1_name = 'glorys to ORCA2 bilin Mapping'
    map2_name = 'ORCA2 to glorys bilin Mapping'
    map_method = 'bilinear'
    normalize_opt = 'frac'
    output_opt = 'scrip'
    restrict_type = 'latitude'
    num_srch_bins = 90 
    luse_grid1_area = .false.
    luse_grid2_area = .false.

    input_file = "t_10.15JUNE2009_fill.nc"
    interp_file = "core2_nordic1_bilin.nc"
    input_name = "T_10_MOD"
    input_start = 1,1,1,1
    input_stride = 1,1,1,1
    input_stop = 0,0,0,1
    input_vars = 'initial_time0_hours'

    output_file = "t_10.15JUNE2009_nordic1.nc"
    output_mode = "create"
    output_dims = 'x', 'y', 'time_counter'
    output_scaling = "T_10_MOD|1.0", "time_counter|86400.0"
    output_name = 'T_10_MOD'
    output_lon = 'x'
    output_lat = 'y'
    output_vars = 'time_counter'
    output_attributes = 'time_counter|units|seconds since 1995-00-00 00:00:00',

 -  shape_inputs are the input fields required by scripshape.f90
 -  first is the interpolation file created by scrip.f90 mapping data to model grid
 -  second is the name of the output weights file to create
 -  third is the east-west wrap to assume in the model (needed when calculating gradient 
          terms in the bicubic scheme); the number is just the number of columns on one side
          that are repeats of those on the opposite side (-1 for not cyclic)
    interp_file = 'glorys_ORCA2_bilin.nc'
    output_file = 'weights_glorys_ORCA2_bilin.nc'
    ew_wrap     = 0

What could be the cause of the error?

Dear m-n-o

I tried the same thing and I have the same error, were you able to fix it? Thanks for your answer

How are the longitudes for your forcing arranged? Are they from 0-360 or -180.0-179? Can you check that?

1 Like

I checked the lengths and yes it is 0-360, I used the same forcing file to create a “weight” file in a regional zone and yes it works fine. The problem is with the global configuration, if anyone can fix it please tell me.

Hello, Elsy.
I had changed my focus on preprocessing interpolation via SOSIE and it works fine.)