Re: a question about topography shading

Hi Xianglei,

There is not a built-in topography file available in NCL. However, you
could accurately mask the Z850 field by comparing the surface pressure
field to it and masking all points whose PS < 850hPa...

Thus, using ind:

a = addfile("hgt.mon.mean.nc","r")
hgt = a->hgt(:,{500.},:,:)

b = addfile("pres.mon.mean.nc","r")
psfc = b->pres

psind = ind(ndtooned(psfc).lt.850)
hgt1D = ndtooned(hgt)
hgt1D(psind) = hgt1D@_FillValue
hgt = (/ onedtond(hgt1D,dimsizes(hgt)) /)
delete(hgt1D)
delete(psind)

or you can use mask (easier):

a = addfile("hgt.mon.mean.nc","r")
hgt = a->hgt(:,{500.},:,:)

b = addfile("pres.mon.mean.nc","r")
psfc = b->pres
hgt = mask(hgt,pres.lt.850,False)

Good luck,
Adam

Xianglei Huang wrote:
> Hi All,
>
> I am trying to use NCL to make a plot with filled contours
> overlapping with contour lines base on some NCEP 850mb fields, and
> meanwhile, I want to have some topography feature shaded (e.g. Tibet
> Plateau). NCEP 850mb fields have values extrapolated over the Tibet
> Plateau. So I have to set them to NaN and meanwhile shade the area. I am
> wondering, instead of manipulating original data, whether there is a
> quick and convenient way to do this in NCL? E.g. is there a buil-in
> topography files we can directly pull out?
>
> Thanks a lot.
>
> Xianglei
>
> _______________________________________________
> ncl-talk mailing list
> ncl-talk_at_ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

-- 
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Adam Phillips			             asphilli_at_ucar.edu
National Center for Atmospheric Research   tel: (303) 497-1726
ESSL/CGD/CAS                               fax: (303) 497-1333
P.O. Box 3000				
Boulder, CO 80307-3000	  http://www.cgd.ucar.edu/cas/asphilli
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