2.0 : WRF netcdf / CTL

[Jennifer Adams]

Patrick,
Please see comments inline.

On Feb 2, 2008, at 11:38 AM, Patrick Reuter wrote:

> Hi everybody,
>
> thank you for providing GraDS 2.0, it's really cool to open NetCDF
> files directly.
>
> However, I have a problem to configure the CTL file correctly for
> the lambert projection (I think PDEF is the issue).
>
> Here is my CTL file :
>
> dset ^file.nc
> dtype netcdf
> undef -888
> TITLE WRF Output Grid: Time, bottom_top, south_north, west_east
> pdef 48 46 LCCR 46.6 1.1 24.5 23.5 46.6 46.6 1.1 27000 27000
The first two args to pdef are the size of the native grid (the
dimensions of the variable in your netcdf file). From the metadata
you showed below, it looks like these numbers should be 49 and 47.
This is likely the source of your errors.
> xdef 48 linear -6.422363 0.319
> ydef 46 linear  40.87268 0.24
The sizes of your XDEF and YDEF axes can be anything you want, since
these define the grid you will be interpolating to -- they do not
have to be the same size as your native grid. I suggest picking a lat/
lon increment that is close to the dx/dy of your native grid, and
then choose a starting lat and an axis dimension that will completely
cover your model domain.
> zdef  27 linear 1 1
> tdef   2000 linear 29jan2008 30mn
> vars 1
> LANDMASK=>l     0  t,y,x    landmask
> endvars
>
> Here is my namelist.wps to configure the area of interest for my
> WRF model :
>
> &geogrid
>  parent_id         = 1,
>  parent_grid_ratio = 1,
>  i_parent_start    = 1,
>  j_parent_start    = 1,
>  e_we          = 49,
>  e_sn          = 47,
>  geog_data_res = '2m',
>  dx = 27000,
>  dy = 27000,
>  map_proj =  'lambert',
>  ref_lat   = 46.6,
>  ref_lon   = 1.1,
>  truelat1  = 46.6,
>  truelat2  = 46.6,
>  stand_lon = 1.1,
>  geog_data_path = '/mnt/scratch/meteo/geog',
> /
>  ref_x = 24.5,
>  ref_y = 23.5,
>
> Unfortunately, the landmask from the WRF output does not coincide
> with the Grads Map - a serious problem for me, evidently !  Please
> see the image illustrating my problem (it's only 20KB).
It's much easier to see if your mask lines up with the coastal
outline if you use 'gxout grfill' instead of contours.
Jennifer

>
> Could anybody tell me if I am in the wrong direction ?
>
> I would appreciate your help. It is so hard to find someone with
> some WRF and GrADS experience to talk to.
>
> Have a nice day !
>   Patrick
>
> <landmask.png>

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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