[ncl-talk] Contour plot with rotated grid shifted to the west

[Guido Cioni]

Hi all,
I’m trying to produce a contour plot with data on a rotated grid. The original data look like that


Since I have the rotated north pole latitude (44.999996) and longitude (144.0) in my data file I used the second example of the support page on rotated grid. 
 
 Res1 at tfDoNDCOverlay=True
 Res1 at mpLimitMode = "Corners" 
 Res1 at mpLeftCornerLatF = lat(0)
 Res1 at mpLeftCornerLonF = lon(0)
 Res1 at mpRightCornerLatF = lat(nlat-1)
 Res1 at mpRightCornerLonF = lon(nlon-1)
 Res1 at mpCenterLatF           = 90 - north_pole_lat  
 Res1 at mpCenterLonF           = 180 + north_pole_lon  

However I get this result ( I believe this is Australia):


After several attempts I was able to plot the data using as bounds the “real” coordinates of the rotated projection, without specifying the center, e.g. :

 Res1 at tfDoNDCOverlay=True
 Res1 at mpLimitMode = "Corners" 
 Res1 at mpLeftCornerLatF = 30.35458 
 Res1 at mpLeftCornerLonF = -75.14440
 Res1 at mpRightCornerLatF = 65.1125
 Res1 at mpRightCornerLonF = 13.87071

But the contour plot is still slightly shifted to the west as you can see in this image:


I know that in the data file my coordinates span from rlon={340,392.875} and rlat={-9.962499,22.512501}. 

What am I missing?
Is there any additional documentation on rotated grid? 

Attached is my NCL script (data are too big). 



Guido Cioni
http://guidocioni.altervista.org <http://guidocioni.altervista.org/> 




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