 Fields f, u, and v are defined on a</span>
  <span class="c">!! semi-staggered Arakawa C-grid:</span>
  <span class="c">!!</span>
  <span class="c">!!     --+---v---+---v---+---v--</span>
  <span class="c">!!       |       |       |</span>
  <span class="c">!! j+1   u   f   u   f   u   f</span>
  <span class="c">!!       |       |       |</span>
  <span class="c">!!     --+---v---+---v---+---v--</span>
  <span class="c">!!       |       |       |</span>
  <span class="c">!!  j    u   f   u   f   u   f</spa