Measurements of galactic cosmic rays made in 1967 on a low-altitude polar satellite exhibited two kinds of quasi-periodic variations which were synchronous with the changes in sector polarity of the interplanetary magnetic field (IMF). A modulation of 30% in the equatorial flux and a north-south asymmetry of roughly the same magnitude were observed. Both effects have been found in the records of surface neutron monitors. Relevance of the equatorial modulation to IMF structure is discussed briefly. It is suggested that the north-south asymmetry is due to intermittent connection between the IMF and GMF (geomagnetic field) and that magnetospheric trapping of charged particles takes place at those times. Evidence is presented that connection occurs on the dayside of the earth. |