I am not understand the caculating of om_p, om_u, on_p, on_u, om_v, on_v. In the file mod_grid.F, they are discribed as

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```
! om_p PSI-grid spacing (meters) in the XI-direction. !
! om_r RHO-grid spacing (meters) in the XI-direction. !
! om_u U-grid spacing (meters) in the XI-direction. !
! om_v V-grid spacing (meters) in the XI-direction. !
! on_p PSI-grid spacing (meters) in the ETA-direction. !
! on_r RHO-grid spacing (meters) in the ETA-direction. !
! on_u U-grid spacing (meters) in the ETA-direction. !
! on_v V-grid spacing (meters) in the ETA-direction. !
```

**om_r**and

**on_r**have been defined as

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```
om_r(i,j)=1.0_r8/pm(i,j)
on_r(i,j)=1.0_r8/pn(i,j)
```

**om_u**and

**on_u**have been defined as

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```
om_u(i,j)=2.0_r8/(pm(i-1,j)+pm(i,j))
on_u(i,j)=2.0_r8/(pn(i-1,j)+pn(i,j))
```

**U-grid spacing (meters) in the XI/ETA-direction**. In this case,

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`on_u(i,j)=2*on_r(i,j)*on_r(i-1,j)/(on_r(i,j)+on_r(i-1,j))`

In my opinion, it should be

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`on_u(i,j)=(1/pn(i,j)+1/pn(i-1,j))/2=(on_r(i,j)+on_r(i-1,j))/2`

**U-grid spacing (meters) in the ETA-direction**. Am I right? Or where am I wrong?