LONG-PERIOD GEOMAGNETIC-PULSATIONS CAUSED BY THE SOLAR-WIND NEGATIVE-PRESSURE IMPULSE ON 22 MARCH 1979 (CDAW-6)

An analysis is made of the long-period geomagnetic pulsations as recor ded at seven Norilsk meridian stations (lambda = 162 degrees, latitudi nal range: 61 degrees-71 degrees N) following abrupt magnetospheric ex pansion during the storm of 22 March 1979 caused by a rapid decrease i n solar wind density. As with the time interval following an abrupt co ntraction at the time of sudden storm commencement, there exist two ty pes of pulsations in the pulsation spectra: latitude-independent (T > 400 s) and latitude-dependent (T < 200 s) pulsations. The first pulsat ion type is interpreted in terms of forced pulsations associated with magnetopause oscillations. The oscillation period is determined by pla sma density in the boundary layer and by the radius of the magnetosphe re (T similar to rho(1/2)R(4)). The latitudinal dependence of the peri od, amplitude and polarization of the second-type pulsations is in agr eement with the resonance mechanism of their origin.