Re: [ferret_users] problem with EF rect_to_curv

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Andrew,
Your original data cross 0 degrees longitude. I am guessing that the 
longitude coordinates have values include both 0 to 42, east of the 
meridian, and 330 to 360 to the west. What's happening is that the 
function is putting in values between 42 and 330 East.  The function 
should work better if you subtract 360 from the values to the west of 
the prime meridian, so that the values in the longitude array are more 
continuous.

yes? LET lon2 = if longitude GT 300 then longitude-360 else longitude

and send lon2 into the function instead of the original longitudes.  Let 
us know if this does the trick, and if so we should add a note about 
this to the documentation.

Ansley

Andrew Ferrone wrote:
> Dear ferreters
>
> I'm working with a regional climate model, which is defined in 
> curvilinear coordinates. For the moment I need to interpolate some 
> globale data on a 1°x1° regular grid onto my curvilinear grid 
> (0.2°x0.2°). For this purpose I tried the external function 
> rect_to_curv in ferret (the lon and lat were used from the output of 
> the regional model). The output I produced was not the one I attended.
>
> I've attached the original data (on the region I am interested in) in 
> CLM_inerpol2.tiff and the result in CLM_inerpol2.tiff. There is 
> clearly a problem when the interoplation crosses the 0° meridian. Has 
> anyone experienced some similar problems with this function and knows 
> hoa to resolve it?
>
> Any help and suggestion is welcome!
>
> Thanks a lot
>
> Andrew
>
>
>
>
>
>
>
> ______________________________________________________________
> Andrew FERRONE
> Physicist, PhD student
> Regional climate modelling, Climate Impacts of Aviation
>
> Université catholique de Louvain (UCL)
> Institut d'astronomie et de géophysique G. Lemaître (ASTR)
> Chemin du Cyclotron, 2, B-1348 Louvain-la-Neuve (Belgium)
> Phone: +32 (0)10 473365   Fax: +32 (0)10 474722
> E-mail: andrew.ferrone@xxxxxxxxxxxx