A question about GEOGRID

[jbensabat]

Hello
I am building a grid to be run by WRFHYDRO.
I manage to prorperly select the domain (~10km * 20 km) and the resolution (500 m)
when I look at the produced coordinates (long_M and LAT_M) I see that the intervals are not exactly equal and there is some kind of periodicity in the cell size sequence.
Is this to be expected ?
Is there a way to enforce equally sized cells (this is very important in the subsequent processing of images on the grid)
thanks
jac

 

[kwerner]

Hi,
I apologize, I'm having a bit of trouble understanding what you mean by "the intervals are not exactly equal and there is some kind of periodicity in the cell size sequence." Can you provide a bit more detail about that statement? Can you also attach your namelist.wps file? Thanks!

 

[jbensabat]

Hi
thanks for your reply
please find attached the namelist.wps file and two additional files: xlat_m.txt and xlong_m.txt corresponding to the xlat_m and xlong_m variables in the created nc file.
we can see that (xlat_m(i+1)-xlat_m(i)) and or (xlong_m(i+1)-xlong_m(i)) are not constant meaning that the cell centers are not equally spaced
best
jac

 

[kwerner]

Hi,
Thanks for the explanation. I'm pretty sure this is due to the map projection, but I'm going to ask another colleague to comment on this, as well. Hopefully they will be able to provide some explanation within a few days. Thank you for your patience.