Correlation of the heliospheric current sheet tilts to galactic cosmic ray modulations and solar wind speed

Abstract

The comparison of the heliospheric current sheet tilts from 1971 to 1992 with cosmic ray intensities recorded at Deep River neutron monitor, solar wind speeds and sunspot numbers, has been investigated. Our results have indicated that the inclination of heliospheric neutral sheet is a suitable parameter for studying disturbances in the interplanetary medium. The observed differences in the sensitivity of cosmic ray intensity to changes in the neutral sheet tilt angles before and after the reversal of interplanetary magnetic field polarity have been studied. A much stronger intensity-tilt angle correlation was found when the solar magnetic field in the north polar region was directed inward than it was outward. The slope of the regression line for the 1981–1989 epoch (qA < 0) was a factor five larger than for the 1971–1978 epoch (qA > 0). A strong correlation was found between the inclination of neutral sheet and solar wind speeds in the ecliptic plane. Furthermore, an excellent correlation was obtained between sunspot numbers and tilt angles of neutral sheet and it was dependent on the reversal of the Sun's magnetic field. The physical significance of our results is discussed.