Re: Question on plotting GOES IR imagery in NCL

Hi Rick,
yes,
  float d(time, xc, yc)
is correct, where lat(xc,yc) and lon(xc,yc) is also true. For making
lat/lon grid box averages, I guess I will use do loops and if statements,
because the projection is irregular.

I can send the figures to your email, because they are a couple of megs and
will get blocked from ncl-talk.

thanks,
Dave

On Thu, Apr 24, 2014 at 5:27 PM, Rick Brownrigg <brownrig@ucar.edu> wrote:

> Hi David,
>
> If your data are just like the example in goes_2.ncl, then brightness
> temperature there is defined as:
>
> float d(time, yc, xc)
>
> rather than
>
> float d(time, lat, lon)
>
> In that case, you'd find the lat/lons by:
>
> brightness = d(0,300,300)
> lon = lon(300, 300)
> lat = lat(300, 300)
>
> Is this the case with your particular dataset? (what does
> printVarSummary(d) yield?)
>
> I don't know about the blockiness issue. Can you post an example of
> what's happening?
>
> Hope that helps…
> Rick
>
> On Apr 24, 2014, at 4:14 PM, David Adams <dave.k.adams@gmail.com> wrote:
>
> > Hi NCLers,
> >
> > I am plotting GOES IR imagery using goes_2.ncl downloaded
> > from http://www.ncl.ucar.edu/Applications/goes.shtml
> >
> > I have two questions.
> >
> > 1) The lat/lon coordinates have both y and x dimension, but the
> brightness
> > temperature, d, is just d(time, lat, lon). So if I print, for example,
> > print(d(0,300,300)) I get a single temperature value, but I don´t know
> what
> > lat, lon it represents.
> >
> > This is what is printed out
> >
> > Variable: d (subsection)
> > Type: float
> > Total Size: 4 bytes
> > 1 values
> > Number of Dimensions: 1
> > Dimensions and sizes: [1]
> > Coordinates:
> > Number Of Attributes: 8
> > time : 1373746500
> > units : K
> > coordinates : lon lat
> > type : GVAR
> > long_name : Temperature
> > _FillValue : 255
> > lat2d : <ARRAY of 481280 elements>
> > lon2d : <ARRAY of 481280 elements>
> > (0) 279.2
> >
> > 279.2 being the temperature value. But what would the lat/lon be?
> > I need to make averages over lat/lon boxes, so I need the lat/lon
> > represented by these indices.
> >
> >
> > 2) Why is the image produced so blocky looking? The guys at
> > SSEC UW plotted the same images with Mc-IDAS at the same resolution and
> > their images look smooth. I can pass on the image, if necessary.
> >
> >
> > thanks in advance,
> > Dave
> > <goes_2.ncl>_______________________________________________
> > ncl-talk mailing list
> > List instructions, subscriber options, unsubscribe:
> > http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Fri Apr 25 13:09:36 2014