Lambert conformal conic projection
Added by Semjon Schimanke over 7 years ago
Hi!
I extracted some data from MARS at ECMWF. The data is stored in grib2 on a Lambert conformal conic projection. First, I got the impression that the CDOs cannot handle this kind of data, especially the grid description. However, know it seems to me they can! :-)
Could somebody please confirm that it is correct to change the grid to a curvilinear with cdo setgridtype,curvilinear. Thanks!
1) The grid description of the downloaded data:
sm_semsc@bi1:TEST$ cdo griddes TEST_T2m.grb #
- gridID 1
#
gridtype = lcc
gridsize = 319225
xsize = 565
ysize = 565
originLon = 341.68
originLat = 17.612
lonParY = 8
lat1 = 48
lat2 = 48
xinc = 11000
yinc = 11000
projection = northpole
cdo griddes: Processed 1 variable ( 0.09s )
sm_semsc@bi1:TEST$
2) Transformation to a curvilinear grid:
sm_semsc@bi1:TEST$ cdo -f nc setgridtype,curvilinear TEST_T2m.grb TEST_T2m_curvi.nc
cdo setgridtype: Processed 1596125 values from 1 variable over 5 timesteps ( 0.64s )
sm_semsc@bi1:TEST$
- gridID 1
#
gridtype = curvilinear
gridsize = 319225
xname = lon
xlongname = longitude
xunits = degrees_east
yname = lat
ylongname = latitude
yunits = degrees_north
xsize = 565
ysize = 565
xvals = -18.3199997 -18.2337151 -18.1473618 -18.0609417 -17.9744511 -17.8878937
-17.8012695 -17.7145748 -17.6278152 -17.540987 -17.454092 -17.3671284
...
To me, everything seems correct. However, I would be happy if somebody could confirm that the data is treated in the right way.
Moreover, I do actually have a "real" question. Assuming that the procedure above is correct for a scalar field as temperature, what about the wind field? Is there any rotation needed if I change the grid to a curvilinear grid?
Thanks for any help or comment,
Semjon
Replies (3)
RE: Lambert conformal conic projection - Added by Karin Meier-Fleischer over 7 years ago
Hi Semjon,
can you upload a Lambert Confom Conic test file.
-Karin
RE: Lambert conformal conic projection - Added by Semjon Schimanke over 7 years ago
Hi Karin,
please find an example file attached. It includes one time step of T2m.
Best regards,
Semjon
RE: Lambert conformal conic projection - Added by Uwe Schulzweida over 7 years ago
The Lambert conformal conic projection is fully supported in CDO. "setgridtype,curvilinear" will change the projection coordinates to geographical coordinates. Only the coordinates will be changed!
There is no rotation needed for this coordinate transformation.