wrong coordinates when plotting from an .nc file

[brian vant-hull]

Hi Costas;
I hope to do something similar in the near future, but
haven't started work on it yet.   What I want to do is
feed in the data plus somewhat irregular (but
gridlike) lat and lon, and get out the data in a
projection that GrADS will plot.

It looks like the projections described in the user
manual *might* do this, but I haven't figured out how
to feed in the original unprojected lat lon data.  I
fear the lat lon grids are expected to be already
mercator projected.  If so I'll have to use IDL or
MatLab to warp my grid to the projection first, or
write a rebinning program and perhaps lose some
resolution.

Anyone else out there: do we need to warp our data to
a given projection outside of GrADS, or will GrADS do
this for us?  I see no provision for feeding arbitrary
lat/lon grids into grads.

(unless plotting as station data - though it doesn't
look like this will provide contoured output.)


--- Costas Douvis <cdouvis at YAHOO.COM> wrote:

> Thank you for your response Brian
>
> My grid has an interval of 50km. So when I use the
> usual "rectilinear" map projection (where the
> coordinates are latitude and longitude and a
> "square" of 10x10 degrees does appear as a square)
> my domain should look stretched towards the pole,
> narrow towards the equator and curved. But it
> doesn't: it appears rectangular
>
> I'm running SUSE 10.0 - 32bit
> and Grads version 1.8SL11
>
> Please let me know if this information is still not
> enough
>
> Kostas
>
> Date:    Fri, 4 Jan 2008 07:18:23 -0800
> From:    brian vant-hull
>
> Subject: Re: wrong coordinates when plotting from an
> .nc file
>
> You'll need to be more precise...for example if the
> coordinates are in equal increments of lat and lon
> then in an equal distance mapping they'd get
> narrower
> towards the poles, but the typical lat-lon plot
> would
> stretch it.  You must have something different, but
> hard to tell what it is.
>
> I may not be able to answer the question, but for
> someone else to answer it they'll need to know alot
> more details!
>
> -Brian.
>
> --- Costas Douvis  wrote:
>
> > Hello and happy new year to everyone
> >
> > I have problem plotting the data from an .nc file.
> I
> > believe that the values of the field are correct
> but
> > the coordinates are "stretched" so that they fit
> in
> > a rectangle. The real grid comes from an RCM model
> > and is getting narrower towards the equator.
> >
> > Thanks in advance for any help
> > Kostas Douvis
>
>
>
>
> ---------------------------------
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Brian Vant-Hull
917-318-4481


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