Association of a "Unipolar" Magnetic Region on the Sun with Changes of Primary Cosmic-Ray Intensity

A new instrument for observing weak magnetic fields on the photosphere of the sun has recently revealed the presence of an unusual area on the solar surface which may be called a "unipolar" magnetic (UM) region because the field is of one sign and no magnetic flux has been found returning to the sun. A region of this type was observed at central solar meridian on seven consecutive solar rotations in 1953. In the present paper it is shown that there is a striking association of this UM region with (1) times of maximum primary cosmic ray intensity as measured by neutron detectors and an ionization chamber, and with (2) the recurring geomagnetic storms—the geomagnetic disturbances being most pronounced ∼3-4 days after both the central meridian passage of the UM region and the time of maximum cosmic-ray intensity.