INFLUENCE OF SHORT-TERM CHANGES IN SOLAR-ACTIVITY ON BARIC FIELD PERTURBATIONS IN THE STRATOSPHERE

The Sazonov index characterising the intensity of meridional circulati on has been used to study the influence of short-term changes in solar activity on baric (pressure) field perturbations in the stratosphere. The results show that stratospheric circulation responses to various manifestations of solar activity may be different. The solar central m eridian passage of active regions leads to the development of stratosp heric perturbations in the case of both west and east QBO phases: Forb ush decreases of galactic cosmic rays are followed by falls of the str atospheric perturbation to minimal levels, irrespective of the QBO pha se. Interplanetary sector boundaries' intersections of Earth lead to i ncreases of the stratospheric perturbation in the case of away/toward boundaries and to decreases of the perturbation in the case of toward/ away boundaries, the effect being dependent on the content of volcanic aerosols in the stratosphere and on the QBO phase. The results suppor t the global electric circuit mechanism put forward by Tinsley et al. (1989). (C) 1997 Elsevier Science Ltd.