...
The edge_dimension attributes are not needed.
ROMS
The ROMS ROMS uses also a C-grid, but it uses on the output file uses different dimensions for all stagger locationseach staggered location. In this case we need all attributes defined above including the edge <i> _dimension attributes..
| Code Block |
|---|
netcdf sed023_last {
dimensions:
ocean_time = UNLIMITED ; // (1 currently)
s_w = 21 ;
eta_rho = 60 ;
xi_rho = 160 ;
tracer = 10 ;
s_rho = 20 ;
eta_u = 60 ;
xi_u = 159 ;
eta_v = 59 ;
xi_v = 160 ;
eta_psi = 59 ;
xi_psi = 159 ;
variables:
double lat_psi(eta_psi, xi_psi) ;
lat_psi:long_name = "latitude of PSI-points" ;
lat_psi:units = "degree_north" ;
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 lon_psi(eta_psi, xi_psi) ;
lon_psi:long_name = "longitude of PSI-points" ;
lon_psi:units = "degree_east" ;
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 ocean_time(ocean_time) ;
ocean_time:long_name = "time since initialization" ;
ocean_time:units = "seconds since 1968-05-23 00:00:00 GMT" ;
ocean_time:calendar = "gregorian" ;
double s_rho(s_rho) ;
s_rho:long_name = "S-coordinate at RHO-points" ;
s_rho:valid_min = -1. ;
s_rho:valid_max = 0. ;
s_rho:standard_name = "ocean_s_coordinate" ;
s_rho:formula_terms = "s: s_rho eta: zeta depth: h a: theta_s b: theta_b depth_c: hc" ;
double s_w(s_w) ;
s_w:long_name = "S-coordinate at W-points" ;
s_w:valid_min = -1. ;
s_w:valid_max = 0. ;
s_w:standard_name = "ocean_s_coordinate" ;
s_w:formula_terms = "s: s_w eta: zeta depth: h a: theta_s b: theta_b depth_c: hc" ;
float u(ocean_time, s_rho, eta_u, xi_u) ;
u:long_name = "u-momentum component" ;
u:units = "meter second-1" ;
u:coordinates = "lat_u lon_u" ;
u:grid = "grid" ; // SGRID attribute
u:location = "edge1" ; // SGRID attribute
float v(ocean_time, s_rho, eta_v, xi_v) ;
v:long_name = "v-momentum component" ;
v:units = "meter second-1" ;
v:coordinates = "lat_v lon_v" ;
v:grid = "grid" ; // SGRID attribute
v:location = "edge2" ; // SGRID attribute
float zeta(ocean_time, eta_rho, xi_rho) ;
zeta:long_name = "free-surface" ;
zeta:units = "meter" ;
zeta:time = "ocean_time" ;
zeta:coordinates = "lat_rho lon_rho" ;
zeta:grid = "grid" ; // SGRID attribute
zeta:location = "face" ; // SGRID attribute
// new SGRID variable
int grid ;
grid:cf_role = grid_topology
grid:topology_dimension = 2 ;
grid:node_dimensions = "xi_psi eta_psi" ;
grid:face_dimensions = "xi_rho: xi_psi (padding: both) eta_rho: eta_psi (padding: both)" ;
grid:edge1_dimensions = "xi_u: xi_psi eta_u: eta_psi (padding: both)" ;
grid:edge2_dimensions = "xi_v: xi_psi (padding: both) eta_v: eta_psi" ;
grid:node_coordinates = "lon_psi lat_psi" ;
grid:face_coordinates = "lon_rho lat_rho" ;
grid:edge1_coordinates = "lon_u lat_u" ;
grid:edge2_coordinates = "lon_v lat_v" ;
grid:vertical_dimensions = "s_rho: s_w (padding: none)" ;
// global attributes:
:Conventions = "CF-1.0" ;
:title = "ROMS/TOMS 2.2 - Adria02 Uber Run" ;
} |
WRF
...
(ARW version)
The WRF-ARW also uses a C-grid. In this case the resulting data is described as a 3D grid topology. It could also be interpreted as a 2D layered model just like Delft3D and ROMS (or those models could also result in 3D grid topologies). A layered approach is more consistent with the UGRID approach that distinguishes between the unstructured mesh in the horizontal and the structured (layered) grid in the vertical, but the 3D grid offers a more symmetric treatment of the staggered U, V and W components.
It might be interesting to verify the result for WRF-NMM since that model uses an E-grid, but I couldn't find an example file.
| Code Block |
|---|
netcdf wrfout_v2_Lambert {
dimensions:
Time = UNLIMITED ; // (13 currently)
DateStrLen = 19 ;
west_east = 73 ;
south_north = 60 ;
west_east_stag = 74 ;
bottom_top = 27 ;
south_north_stag = 61 ;
bottom_top_stag = 28 ;
variables:
char Times(Time, DateStrLen) ;
float U(Time, bottom_top, south_north, west_east_stag) ;
U:description = "x-wind component" ;
U:units = "m s-1" ;
U:grid = "grid" ; // SGRID attribute
U:location = "face1" ; // SGRID attribute
float V(Time, bottom_top, south_north_stag, west_east) ;
V:description = "y-wind component" ;
V:units = "m s-1" ;
V:grid = "grid" ; // SGRID attribute
U:location = "face2" ; // SGRID attribute
float W(Time, bottom_top_stag, south_north, west_east) ;
W:description = "z-wind component" ;
W:units = "m s-1" ;
W:grid = "grid" ; // SGRID attribute
W:location = "face3" ; // SGRID attribute
float T(Time, bottom_top, south_north, west_east) ;
T:description = "perturbation potential temperature (theta-t0)" ;
T:units = "K" ;
W:grid = "grid" ; // SGRID attribute
W:location = "volume" ; // SGRID attribute
float XLAT(Time, south_north, west_east) ;
XLAT:description = "LATITUDE, SOUTH IS NEGATIVE" ;
XLAT:units = "degree_north" ;
float XLONG(Time, south_north, west_east) ;
XLONG:description = "LONGITUDE, WEST IS NEGATIVE" ;
XLONG:units = "degree_east" ;
float ZNU(Time, bottom_top) ;
ZNU:description = "eta values on half (mass) levels" ;
ZNU:units = "" ;
float ZNW(Time, bottom_top_stag) ;
ZNW:description = "eta values on full (w) levels" ;
ZNW:units = "" ;
// SGRID variable
int grid ;
grid:cf_role = grid_topology
grid:topology_dimension = 3 ;
grid:node_dimensions = "west_east_stag south_north_stag bottom_top_stag" ;
grid:volume_dimensions = "west_east: west_east_stag (padding: none) south_north: south_north_stag (padding: none) bottom_top: bottom_top_stag (padding: none)" ;
grid:volume_coordinates = "XLONG XLAT ZNU" ;
// global attributes:
:TITLE = " OUTPUT FROM WRF V2.0 MODEL" ;
} |