Re: resample one grid to another in IDV?

• To: Stuart Maclean <stuart@xxxxxxxxxxxxxxxxxx>
• Subject: Re: resample one grid to another in IDV?
• From: Don Murray <dmurray@xxxxxxxxxxxxxxxx>
• Date: Fri, 18 Nov 2005 08:00:34 -0700

Hi Stuart-

Stuart Maclean wrote:

I have data from a LambertConformal model grid M over the pacific northwest. I'd like to compare the model values (for say geopotential height) with the RUC20 grid R.

Manually, I can project M's x,y points to lat,lon, then project those lat/lons back to the x,y grid points of R and resample R's values (using e.g. weighted average) and assign the values to a new grid M'.

Can I do this visually in IDV, so that a two pane display will show M and M', with the default map area for both just M, i.e. not the much bigger R.

You could do this one of two ways:

- Load in your two datasets.

Display only:

- Use the File->New->Display Window->Map Display->Two Panes
menu to create a Two Panel display.
- Click in the window you want to put a display for the base
projection and load in the data.  That will set the projection
for both windows.
- In both windows, uncheck the Projections->Reset Projection With
New Data option.
- click in the other window (you will see a blue highlight around
the selected window) and load the data from the other model
into that window.  The data will automatically be reprojected
to the display projection.  If you don't want to see data outside
the box (since the domain is bigger), use the View->Clip View at Box
menu.
- Both windows will share zoom/pan/rotate functionality.

Resample the data:

- You can reproject data using the System->Resample Grid
formula.  Select this formula and the type of display
you want.  Then, when prompted, choose the grid you
want to resample for "grid" and the grid with the
domain you want to sample to for the "gridWithNewDomain"
parameter.

This method is sort of overkill because you can accomplish
pretty much the same thing with the display method above.

If not in IDV, does anyone know of a toolset to do this? I have noted the many tools under

http://www.unidata.ucar.edu/software/netcdf/software.html

but none seems to quite do what I want.

Any help appreciated

Let me know if you have any problems or questions with the
methods above.

Don
*************************************************************
Don Murray                               UCAR Unidata Program
dmurray@xxxxxxxxxxxxxxxx                        P.O. Box 3000
(303) 497-8628                              Boulder, CO 80307
http://www.unidata.ucar.edu/staff/donm
        "Time makes everyone interesting, even YOU!"
*************************************************************

• References:
  • resample one grid to another in IDV?
    • From: Stuart Maclean