[ncl-talk] rot lat_lon to regular lat_lon

[Dave Allured - NOAA Affiliate]

If the coordinate variables are 1-D, then this file is probably already
converted into a regular lat/lon grid.  The region to plot is the min and
max of the coordinate variables.  The global attributes are historical and
may apply to the source file before the conversion was done.

Just plot this as a normal regional data file with 1-D lat/lon coordinates.


On Mon, Jul 20, 2026 at 9:07 PM Debasish Hazra via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hi,
> I have a file which is in rotate lat_lon grid with the following
> attributes, but lat and lon are not 2 dimensional. How to plot this data
> and also how to convert it into regular lat lon ?
>
>  file global attributes:
>       cen_lat : 50
>       cen_lon : -118
>       dlat : 0.1169081
>       dlon : 0.1169081
>       dtp : 180
>       fhzero : 1
>       grid : rotated_latlon
>       grid_id : 1
>       lat1 : -28.5
>       lat2 : 28.5
>       lon1 : -45.25
>       lon2 : 45.25
>       dimensions:
>       time = 1
>       grid_yt = 488
>       grid_xt = 775
> variables:
>       float aod ( time, grid_yt, grid_xt )
>          _FillValue :   9.99e+20
>          cell_methods : time: point
>          long_name :    total aerosol optical depth at 550 nm
>          missing_value :        9.99e+20
>          output_file :  phy
>          units :        numerical
>
>       double grid_xt ( grid_xt )
>          cartesian_axis :       X
>          long_name :    rotated T-cell longiitude
>          units :        degrees
>
>       double grid_yt ( grid_yt )
>          cartesian_axis :       Y
>          long_name :    rotated T-cell latiitude
>          units :        degrees
>
>       double time ( time )
>          calendar :     JULIAN
>          calendar_type :        JULIAN
>          cartesian_axis :       T
>          long_name :    time
>          units :        hours since 2026-07-14 06:00:00
>
> Appreciate your help on this.
> Thanks,
> Debasish
>
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