Re: Longitude weirdness

[Steve Cousins <cousins@xxxxxxxxxxxxxxxxxxxxxxx>]

On Fri, 27 Jun 2003, Steve Cousins wrote:

> > Since the axis in the NetCDF file is modulo, it wouldn't matter which start point
> > you use in the XML axis definition.
> > if the axis is irregular, subtract 20 from all of the <v>.....</v> entries.
> > 
> > If the axis is regular, you can define your axis in the XML file like this:
> > 
> >    <mf1_11b_19990515_nc_longitude units="degrees" type="x">
> >        <arange start="0.0" step = "0.2812" size="1280"/>
> >    </mf1_11b_19990515_nc_longitude>
> > 
> > In fact, try it this way first (less editing) and see if you like the way LAS
> > responds.
> 
> That works!  

Hi Again,

Well I guess I spoke too soon.  It does work a lot better as far as the
map applet goes however, when I "Get Data" for the whole world, it goes
from 180 degrees to 20 degrees East.  It cuts off from 20 degrees East to
179 degrees East.  

The 20 degree East mark seems to be the cutoff point on the other side
too.  It has strange properties though.  If I select:

Select:			Shows:
32 W - 136 E		32 W - 136 E
32 W - 137 E		32 W - 20 E
31 W - 137 E		31 W - 137 E
31 W - 138 E		31 W - 20 E
.
.
1 W - 167 E		1 W - 167 E
1 W - 168 E		1 W - 20 E

This continues on if you go past Degree 0 but changes the West boundary
instead of the East one:

Select:			Shows:
-0 E - 168 E		-0 E - 168 E
-0 E - 169 E		20 E - 169 E
.
.
4  E - 172 E		4  E - 172 E
4  E - 173 E		20 E - 173 E
5  E - 173 E		5  E - 174 E
5  E - 174 E		20 E - 174 E


So, everything seems to work well as long as you select a width less than
169 degrees.  The exception is that if you start from 180 W you can go all
the way to 20 E but no further.  

Does this make any sense?  Any idea what is going on here?

Thanks,

Steve

_____________________________________________________________
 Steve Cousins                 Email: cousins@umit.maine.edu
 Research Associate            Phone: (207) 581-4302
 Ocean Modeling Group
 School of Marine Sciences     208 Libby Hall
 University of Maine           Orono, Maine 04469