The initial boundary value problems associated with the inviscid barot
ropic potential vorticity equation in the beta-plane and its viscous a
nalogue are considered. It is shown that the solution velocity to the
viscous equation converges to the inviscid solution in a C-1 sense for
finite times and that, under additional smoothness assumptions on the
inviscid flow, this convergence can be extended to C-3. Moreover, thi
s convergence occurs as O(epsilon), where epsilon is the viscous param
eter. This particular form of vanishing viscosity is of relevance in a
nalysing viscosity induced advection for barotropic models. (C) 1997 A
cademic Press.