Strange behaviour of rcm2points with opt=2

Hi NCL team,

I'm seeing a strange behaviour of the rcm2points function inserting
missing values in the results, where input data should be available. The
values seem to be correct when using the opt=1 (inverse distance
weighting), but with opt=2 (bi-linear interpolation) the results contain
(to me) unexplainable missing values.

I've attached a small script where the problem occurs. The scripts read
two two-dimensional arrays (x2d,y2d) which contain the lat,lon
coordinates of a weather model grid. It then reads a short list of
lat/lon points. Afterwards, it tries to find the location of these
points in array index space by using the rcm2points function.
Since the points are not located anywhere near the data boundaries,
there is no reason for missing values to occurr.

The list of three lat/lon points is...
(0,0) 47
(0,1) -5.405255
(1,0) 47
(1,1) -5.31714
(2,0) 47
(2,1) -5.229024

The resulting list of three index-space points is...
(0,0) 97.98473
(0,1) 180.314
(1,0) -999
(1,1) -999
(2,0) 99.83066
(2,1) 179.9179

On can see that the first and third points are well away of the
boundaries, as the arrays are dimensioned (338,393). To me there is not
reason, why the second point is returned as missing. Changing opt=1 also
gives reasonable results.

Any ideas are appreciated.
Oli

PS. Please contact in case you would like the dump.nc input file. I've
put it onto a publicly available FTP server.
 
________________________________________

Oliver Fuhrer
Numerical Models

Federal Departement of Home Affairs FDHA
Federal Office of Meteorology and Climatology MeteoSwiss

Kraehbuehlstrasse 58, P.O. Box 514, CH-8044 Zurich, Switzerland

Tel. +41 44 256 93 59
Fax +41 44 256 92 78
oliver.fuhrer@meteoswiss.ch
www.meteoswiss.ch - First-hand information
  

 
________________________________________

Oliver Fuhrer
Numerical Models

Federal Departement of Home Affairs FDHA
Federal Office of Meteorology and Climatology MeteoSwiss

Kraehbuehlstrasse 58, P.O. Box 514, CH-8044 Zurich, Switzerland

Tel. +41 44 256 93 59
Fax +41 44 256 92 78
oliver.fuhrer@meteoswiss.ch
www.meteoswiss.ch - First-hand information
  

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