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Now one needs to decide where the "LAM grid" should be located on the "global grid".
It is best to center the "LAM grid" over the grid equator of the "global grid" to keep the grid boxes as square as possible.
Imagine the "LAM grid" is a piece of paper and you want to pin it in a certain location on a global map. First you would put a pin in the piece of paper in the "reference point", defined by 'Grd_iref' and 'Grd_jref'. Then you would pin it at a certain location on the "global grid", defined by 'Grd_lon1' and 'Grd_lat1' (in longitude and latitude of the rotated grid!).
First one needs to choose any one grid point on the "LAM grid" by setting 'Grd_iref' and 'Grd_jref'. This point is called the "reference point". I find it easiest to choose the middle point of the grid (something that is not done in the example image above). Meaning set 'Grd_iref' to 'Grd_ni/2' and 'Grd_jref' to 'Grd_nj/2'. But you have to put the values!
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Grd_lonr = 180.0, Grd_latr = 0.0
Click here to find out how to set blending and pilot area (halo).
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