Re: Question on plotting GOES IR imagery in NCL

From: Rick Brownrigg <brownrig_at_nyahnyahspammersnyahnyah>
Date: Thu Apr 24 2014 - 16:27:04 MDT

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 donīt 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
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Received on Thu Apr 24 16:27:14 2014

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