  We consider three-dimensional geophysical flows at arbitrary latitude and
with constant vorticity beneath a wave train and above a flat bed in the
$\beta$-plane approximation with centripetal forces. We consider the $f$-plane
approximation as well as the $\beta$-plane approximation. For the $f$-plane
approximation, we prove that there is no bounded solution. For the
$\beta$-plane approximation, we show that the flow is necessarily irrotational
and the free surface is necessarily flat if it exhibits a constant vorticity.
Our results reveal some essential differences from those results in the
literature, due to the presence of centripetal forces. Moreover, for the case
exhibiting the surface tension, we prove that there are no flows exhibiting
constant vorticity.
