next up previous contents
Next: High Latitude Filtering Up: Model Code and Numerics Previous: Model Code and Numerics

Grid Boundaries

 

The east/west boundaries are periodic, and the north/south boundaries are solid wall. At the north-south boundaries, meridional velocity v is set to zero. Thus, at the northern boundary, both v0(i,NY) and v1(i,NY) are set to zero. To describe the southern boundary, an extra point has been added at the southern-most extent of arrays v0 and v1. Thus, the y-direction of these two arrays (and arrays which depend on them, such as psi0) are actually dimensioned 0:NY instead of 1:NY, as the other arrays (such as u0 and u1) are. An exception is vort0, which one might think is dimensioned 0:NY, but actually is dimensioned 1:NY. Then, this southern-most point of both v0 and v1 (i.e. v0(i,0) and v1(i,0)) are set to zero. As a reminder, v0(i,0) and v1(i,0) describe tex2html_wrap_inline2530 and tex2html_wrap_inline2532 , respectively. To avoid special code for for advection at the northern and southern boundaries the array holding the prognostics tex2html_wrap_inline2534 and tex2html_wrap_inline2536 are dimensioned from j=0 to j=ny+1.

Note that though the east/west boundaries are periodic, numerically this is implemented without the use of ghostpoints.

Between V2.0 and V2.1, there has been a shift of grid points that offsets which point occurs at the equator. This is to accommodate the pole-to-pole option in V2.1. In V2.1 and higher versions, the equator has a v (v0 and v1) point, with T and u(u0 and u1) points half a grid north and south of the equator. In V2.0 and lower, the equator has a T point.



Climate Systems Interaction Group
Sun Aug 25 00:58:46 PDT 2002