t_49 :: (real ~ "1" on
         (i = 1 .. nlon + 1 by
          j = 0 .. nlat + 1 by
          k = 1 .. nlev
         )
        )


CSE Eliminated

t_49 := ( (varidx(p, [i, j, k]) + varidx(p, [i, j + 1, k]))
        - varidx(p, [i, j, k + 1])
        - varidx(p, [i, j + 1, k + 1])
        )