Solar Disturbances and the Cosmic Ray Equator

The location of the cosmic ray equator off the west coast of Africa has been established from measurements obtained with a shipboard neutron monitor which made ten crossings between November, 1956, and October, 1958. From the individual determinations of the point of minimum cosmic ray intensity, the mean geographical position was 6.7 ± 0.8° N at 14° W. Direct measurements of zero magnetic inclination were made at the same time in the immediate vicinity of this point.

Although solar and geophysical activity varied considerably during this period, the location of the cosmic ray equator appears to have remained fixed within approximately 1°. However, the possibility of a small progressive change of about the magnitude of the uncertainty cannot be precluded.

Comparison of the results with plots of measurements of the magnetic elements along the ship’s route reveals a significant difference between the location of the points of maximum horizontal intensity and minimum cosmic ray intensity.