[ncl-talk] Lat lon span of selected grid from wrfout

[Mary Haley]

Jake,

wrf_user_ij_to_ll should give you the lon, lat value very close to the
location where the i,j lines intersect.

If you look at example 2 on the documentation page:

http://www.ncl.ucar.edu/Document/Functions/WRF_arw/wrf_user_ij_to_ll.shtml

it shows how you can compare the wrf_user_ij_to_ll lat,lon value with what
you get if you simply read XLAT and XLONG off the file and subscript them
with the same index values (minus 1, since NCL goes from 0 to 1)

To help you visually see what's going on, I've included a modified version
of one of those examples that shows how to draw the WRF lat/lon grid with
two markers: one from the values returned by wrf_user_ij_to_ll, and one
from subscripting XLAT/XLONG using the same i,j values. You will see they
are pretty much identical, since the red and blue circles are concentric.

Hopefully you can plug in your WRF output file and your i,j values, and get
a similar set of plots. You will likely need to change these four resources
for the zoomed in plot to be whatever area you are interested in.

;---Zoom in on plot
  res at mpMinLatF     = 32
  res at mpMaxLatF     = 37
  res at mpMinLonF     = -95
  res at mpMaxLonF     = -87


--Mary



On Sat, Dec 3, 2016 at 3:17 AM, Jacob Alberto Garcia <
jacob_garcia at dlsu.edu.ph> wrote:

> Hi i was able to get the lat lon coordinates using the   wrf ll to latlon
>
> But now im wondering, since im interested in that cell, for example [27,
> 27] it only gives me one lat lon ( using wrf ll to lat lon) but i want to
> know the span of it. Like the other three sides of that grid.
>
> I thought of using my grid dist (4km) to add or subtract from the output
> given by the ll to lat lon function, but as ive mentioned earlier this
> function only gives me one lat lon for that grid of interest. But what part
> of the grid? Upper left? Or is it the one at the center?
>
> Hoping for your help!
> Jake
>
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