[gradsusr] Help on displaying NetCDF data with Grads.
aanil649 at gmail.com
aanil649 at gmail.com
Tue Jan 28 02:09:56 EST 2014
Hi Jennifer and GrADS Users,
I have NetCDF file (RTOFS Global
<http://nomads.ncep.noaa.gov/pub/data/nccf/com/rtofs/prod/rtofs.20140127/rto
fs_glo_2ds_n024_daily_prog.nc> ) downloaded from NOMADS server
<http://nomads.ncep.noaa.gov/pub/data/nccf/com/rtofs/prod/rtofs.20140127/rto
fs_glo_2ds_n024_daily_prog.nc> . Ncdump of the file is
netcdf
D\:/OceanCurrentData/2014/01/22/20140122_rtofs_glo_2ds_n024_daily_prog {
dimensions:
MT = UNLIMITED ; // (1 currently)
Y = 3298 ;
X = 4500 ;
Layer = 1 ;
variables:
double MT(MT) ;
MT:long_name = "time" ;
MT:units = "days since 1900-12-31 00:00:00" ;
MT:calendar = "standard" ;
MT:axis = "T" ;
double Date(MT) ;
Date:long_name = "date" ;
Date:units = "day as %Y%m%d.%f" ;
Date:C_format = "%13.4f" ;
Date:FORTRAN_format = "(f13.4)" ;
int Layer(Layer) ;
Layer:units = "layer" ;
Layer:positive = "down" ;
Layer:axis = "Z" ;
int Y(Y) ;
Y:point_spacing = "even" ;
Y:axis = "Y" ;
int X(X) ;
X:point_spacing = "even" ;
X:axis = "X" ;
float Latitude(Y, X) ;
Latitude:standard_name = "latitude" ;
Latitude:units = "degrees_north" ;
float Longitude(Y, X) ;
Longitude:standard_name = "longitude" ;
Longitude:units = "degrees_east" ;
Longitude:modulo = "360 degrees" ;
float u_velocity(MT, Layer, Y, X) ;
u_velocity:coordinates = "Longitude Latitude Date" ;
u_velocity:standard_name = "eastward_sea_water_velocity" ;
u_velocity:units = "m/s" ;
u_velocity:_FillValue = 1.267651e+030f ;
u_velocity:valid_range = -2.09935f, 2.310735f ;
u_velocity:long_name = " u-veloc. [90.9H]" ;
float v_velocity(MT, Layer, Y, X) ;
v_velocity:coordinates = "Longitude Latitude Date" ;
v_velocity:standard_name = "northward_sea_water_velocity" ;
v_velocity:units = "m/s" ;
v_velocity:_FillValue = 1.267651e+030f ;
v_velocity:valid_range = -2.275719f, 2.274807f ;
v_velocity:long_name = " v-veloc. [90.9H]" ;
float sst(MT, Y, X) ;
sst:coordinates = "Longitude Latitude Date" ;
sst:standard_name = "sea_surface_temperature" ;
sst:units = "degC" ;
sst:_FillValue = 1.267651e+030f ;
sst:valid_range = -6.057281f, 32.59346f ;
sst:long_name = " sea surf. temp. [90.9H]" ;
float sss(MT, Y, X) ;
sss:coordinates = "Longitude Latitude Date" ;
sss:standard_name = "sea_surface_salinity" ;
sss:units = "psu" ;
sss:_FillValue = 1.267651e+030f ;
sss:valid_range = 1.749605f, 40.75261f ;
sss:long_name = "sea surf. salnity [90.9H]" ;
float layer_density(MT, Layer, Y, X) ;
layer_density:coordinates = "Longitude Latitude Date" ;
layer_density:standard_name = "sea_water_potential_density"
;
layer_density:units = "sigma" ;
layer_density:_FillValue = 1.267651e+030f ;
layer_density:valid_range = 0.f, 0.f ;
layer_density:long_name = " density [90.9H]" ;
// global attributes:
:Conventions = "CF-1.0" ;
:title = "HYCOM ATLb2.00" ;
:institution = "National Centers for Environmental
Prediction" ;
:source = "HYCOM archive file" ;
:experiment = "90.9" ;
:history = "archv2ncdf2d" ;
}
The dataset has 32 hybrid layers and a horizontal grid size of (4500 x 3298)
. The grid has an Arctic bi-polar patch north of 47°N and a Mercator
projection south of 47°N through 78.6°S. More details can be found at link
<http://polar.ncep.noaa.gov/global/about/?> .
The CTL file Am using is to display variable values :
dset ^20140122_rtofs_glo_2ds_n024_daily_prog.nc
title HYCOM ATLb2.00
undef 1.26765e+30
dtype netcdf
XDEF 4320 LINEAR 74.16 0.08333
YDEF 2160 LINEAR -90. 0.08333
zdef 1 linear 1 1
tdef 1 linear 00Z31DEC1900 1mn
options template
PDEF 4500 3298 bilin sequential binary-big
D:\OceanCurrentData\PDEF\pdef_ncep_global
vars 8
Date=>date 0 t date
Latitude=>latitude 0 y,x latitude
Longitude=>longitude 0 y,x longitude
u_velocity=>u_velocity 1 t,z,y,x u-veloc. [90.9H]
v_velocity=>v_velocity 1 t,z,y,x v-veloc. [90.9H]
sst=>sst 0 t,y,x sea surf. temp. [90.9H]
sss=>sss 0 t,y,x sea surf. salnity [90.9H]
layer_density=>layer_density 1 t,z,y,x density [90.9H]
endvars
The file used for interpolation pdef_ncep_global can be downloaded from
http://nomad3.ncep.noaa.gov/pub/rtofs_global/20140122/
When Am displaying current variables u_velocity and v_velocity in GrADS with
following commands
ga->open
C:/OceanCurrentData/2014/01/22/20140122_rtofs_glo_2ds_n024_daily_prog.ctl
ga-> set lon -180 180
ga-> set lat -90 90
ga-> d skip(u_velocity*1.95,50,50);v_velocity*1.95
The output produced with above commands is attached herewith. The output
shown to grads windows is only for lon 74.16 to 179.95 approx. Understand
that Longitude starts is set 74.16 in XDEF entry in CTL file (as NetCDF file
contains rectiliear data from 74.16 onwards and data is packed 1/12 th the
degree)
XDEF 4320 LINEAR 74.16 0.08333
is defining Start point of LON.
My Question is : How can I make command d
skip(u_velocity*1.95,50,50);v_velocity*1.95 working so that plot is on
entire globe ??? not for just LON 74.16 to 179.65. (Understand that NetCDF
file has linear data from 74.16 to 434, but How can I make these cartesion
coordinate equivalent to geographical coordinates ????)
Center of Plot is necessarliy to be at POINT (0,0) as plot need to be
overlaid on google map.
Any help or guidance would be greatly appreciated.
Thanks & Regards
Anil Kumar – Sr. Software Developer
OceanManager Inc. | <http://www.oceanmanager.com/> www.oceanmanager.com
Tel: +1 (801)-758-7101, (801)-758-7207
Fax: +1 (801)-758-7101
OceanManager- Marine Software
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20140128/3912d508/attachment-0001.html
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OUTPUT.jpg
Type: image/jpeg
Size: 207179 bytes
Desc: not available
Url : http://gradsusr.org/pipermail/gradsusr/attachments/20140128/3912d508/attachment-0001.jpg
More information about the gradsusr
mailing list