CDO

Hello,

I am trying to use a grid defined in a roms_grd.nc file to regrid some data to this grid. The problem is I cannot for the life of me work out why CDO refuses to recognise the grids in the file. They appear to conform to the CF convention - Panoply can succesfully display the data on these grids and it is usually quite picky about the convention.

Clues: The output of cdo sinfo roms_grd.nc is:

Horizontal grids :
1 : generic > size : dim = 30351 nx = 201 ny = 151
2 : generic > size : dim = 30200 nx = 200 ny = 151
3 : generic > size : dim = 30150 nx = 201 ny = 150
4 : generic > size : dim = 30000 nx = 200 ny = 150

The ncdump -h of roms_grd.nc is:

@netcdf roms_grd {
dimensions:
xi_u = 200 ;
eta_u = 151 ;
xi_v = 201 ;
eta_v = 150 ;
xi_rho = 201 ;
eta_rho = 151 ;
xi_psi = 200 ;
eta_psi = 150 ;
one = 1 ;
two = 2 ;
four = 4 ;
bath = 1 ;

variables:
double xl(one) ;
xl:long_name = "domain length in the XI-direction" ;
xl:units = "meter" ;
double el(one) ;
el:long_name = "domain length in the ETA-direction" ;
el:units = "meter" ;
double depthmin(one) ;
depthmin:long_name = "Shallow bathymetry clipping depth" ;
depthmin:units = "meter" ;
double depthmax(one) ;
depthmax:long_name = "Deep bathymetry clipping depth" ;
depthmax:units = "meter" ;
char spherical(one) ;
spherical:long_name = "Grid type logical switch" ;
spherical:option_T = "spherical" ;
double angle(eta_rho, xi_rho) ;
angle:long_name = "angle between xi axis and east" ;
angle:units = "degree" ;
double h(eta_rho, xi_rho) ;
h:long_name = "Final bathymetry at RHO-points" ;
h:coordinates = "lon_rho lat_rho" ;
h:units = "meter" ;
double hraw(bath, eta_rho, xi_rho) ;
hraw:long_name = "Working bathymetry at RHO-points" ;
hraw:units = "meter" ;
double alpha(eta_rho, xi_rho) ;
alpha:long_name = "Weights between coarse and fine grids at RHO-points" ;
double f(eta_rho, xi_rho) ;
f:long_name = "Coriolis parameter at RHO-points" ;
f:units = "second-1" ;
double pm(eta_rho, xi_rho) ;
pm:long_name = "curvilinear coordinate metric in XI" ;
pm:units = "meter-1" ;
double pn(eta_rho, xi_rho) ;
pn:long_name = "curvilinear coordinate metric in ETA" ;
pn:units = "meter-1" ;
double dndx(eta_rho, xi_rho) ;
dndx:long_name = "xi derivative of inverse metric factor pn" ;
dndx:units = "meter" ;
double dmde(eta_rho, xi_rho) ;
dmde:long_name = "eta derivative of inverse metric factor pm" ;
dmde:units = "meter" ;
double x_rho(eta_rho, xi_rho) ;
x_rho:long_name = "x location of RHO-points" ;
x_rho:units = "meter" ;
double x_u(eta_u, xi_u) ;
x_u:long_name = "x location of U-points" ;
x_u:units = "meter" ;
double x_v(eta_v, xi_v) ;
x_v:long_name = "x location of V-points" ;
x_v:units = "meter" ;
double x_psi(eta_psi, xi_psi) ;
x_psi:long_name = "x location of PSI-points" ;
x_psi:units = "meter" ;
double y_rho(eta_rho, xi_rho) ;
y_rho:long_name = "y location of RHO-points" ;
y_rho:units = "meter" ;
double y_u(eta_u, xi_u) ;
y_u:long_name = "y location of U-points" ;
y_u:units = "meter" ;
double y_v(eta_v, xi_v) ;
y_v:long_name = "y location of V-points" ;
y_v:units = "meter" ;
double y_psi(eta_psi, xi_psi) ;
y_psi:long_name = "y location of PSI-points" ;
y_psi:units = "meter" ;
double lon_rho(eta_rho, xi_rho) ;
lon_rho:long_name = "longitude of RHO-points" ;
lon_rho:units = "degree_east" ;
double lon_u(eta_u, xi_u) ;
lon_u:long_name = "longitude of U-points" ;
lon_u:units = "degree_east" ;
double lon_v(eta_v, xi_v) ;
lon_v:long_name = "longitude of V-points" ;
lon_v:units = "degree_east" ;
double lon_psi(eta_psi, xi_psi) ;
lon_psi:long_name = "longitude of PSI-points" ;
lon_psi:units = "degree_east" ;
double lat_rho(eta_rho, xi_rho) ;
lat_rho:long_name = "latitude of RHO-points" ;
lat_rho:units = "degree_north" ;
double lat_u(eta_u, xi_u) ;
lat_u:long_name = "latitude of U-points" ;
lat_u:units = "degree_north" ;
double lat_v(eta_v, xi_v) ;
lat_v:long_name = "latitude of V-points" ;
lat_v:units = "degree_north" ;
double lat_psi(eta_psi, xi_psi) ;
lat_psi:long_name = "latitude of PSI-points" ;
lat_psi:units = "degree_north" ;
double mask_rho(eta_rho, xi_rho) ;
mask_rho:long_name = "mask on RHO-points" ;
mask_rho:option_0 = "land" ;
mask_rho:option_1 = "water" ;
double mask_u(eta_u, xi_u) ;
mask_u:long_name = "mask on U-points" ;
mask_u:option_0 = "land" ;
mask_u:option_1 = "water" ;
double mask_v(eta_v, xi_v) ;
mask_v:long_name = "mask on V-points" ;
mask_v:option_0 = "land" ;
mask_v:option_1 = "water" ;
double mask_psi(eta_psi, xi_psi) ;
mask_psi:long_name = "mask on PSI-points" ;
mask_psi:option_0 = "land" ;
mask_psi:option_1 = "water" ;

// global attributes:
:title = "BOSTON" ;
:date = "29-Mar-2012" ;
:type = "ROMS grid file" ;
}@

Final clue:

Running ncdump roms_grd.nc > roms_grd.cdl; ncgen -o test.nc roms_grd.cdl

produces a test.nc that cannot be read by cdo:

cdo sinfo: Open failed on >test.nc<
Unsupported file type

The roms_grd.nc file is attached.