In analogy to quasigeostrophic, characterizing a model in which a nondivergent velocity field is used in every context except in the divergence term in the vorticity equation. This velocity field is computed from some steady-state equation such as the balance equation (thus including nonlocal accelerations) and is more general than the geostrophic approximation. The horizontal divergence must, of course, be computed from the equation of continuity or from another equation.