INFLUENCE OF VOLCANIC-ERUPTIONS ON THE TROPOSPHERE THROUGH STRATOSPHERIC DYNAMICAL PROCESSES IN THE NORTHERN-HEMISPHERE WINTER

It has been suggested that the zonal-mean stratospheric zonal-wind anomalies can propagate downward into the troposphere, producing considerable changes. On the other hand, volcanic aerosols are thought to produce a stronger polar vortex in the winter stratosphere. If these suggestions are correct, the influence of volcanic eruptions call be expected to produce changes in the northern hemisphere winter troposphere through stratospheric process. In the present study, this idea is examined by analyzing changes in the January circulation after three recent volcanic eruptions. Regional features of observed changes ill tropospheric temperatures due to volcanic eruptions can be explained by the changes in the propagation of stationary waves associated with dipole-type anomalies in the zonal-mean zonal winds, which are similar to those observed in a previous work on the influence of polar night jet.