  An explicit expression is obtained for the sectional curvature in the plane
spanned by two stationary flows, cos(k, x) and cos(l, x). It is shown that for
certain values of the wave vectors k and l the curvature becomes positive for
alpha > alpha_0, where 0 < alpha_0 < 1 is of the order 1/k. This suggests that
the flow corresponding to such geodesics becomes more stable as one goes from
usual Eulerian description to the Euler-alpha model.
