Inertial Trajectories on a Rotating Earth

Abstract The trajectories of inertial flows on a rotating earth are calculated, in an attempt to reconcile the differing heuristic suggestions in the literature on the subject. It is shown that westward propagating “nearly closed” orbits are possible away from the equator. For orbits crossing the equator, we find a stationary, “figure-eight- like” orbit, together with eastward and westward propagating modes. Near the pole, the convergence of longitudes causes the trajectories to be deflected cyclonically in contrast to the deflection of the Coriolis force, giving rise to a westward propagating mode that meanders about a central latitude.