Latitudinal and solar-cycle dependence of the interplanetary magnetic field predominant polarity

A study of the predominant interplanetary magnetic field (IMF) polarity is made, for the time period 1957-1977. The examination of the mean positive and negative sector width for time periods (semesters) for which the Earth was in northern and southern heliolatitudes shows that the predominant polarity for every semester follows, up to a certain extent, the Rosenberg-Coleman effect. However, the statistical support is not satisfactory. The same conclusion was pointed out by a similar study of data grouped over various phases of the solar cycle. Additionally the relative frequency of positive (negative) IMF polarity days, appeared over a mean solar rotation, shows that the general pattern of the mean IMF has a tendency to reoccur in the homologous (corresponding) phases of different solar cycles. © 1982 D. Reidel Publishing Company

Latitudinal and solar-cycle dependence of the interplanetary magnetic field predominant polarity

A study of the predominant interplanetary magnetic field (IMF) polarity is made, for the time period 1957-1977. The examination of the mean positive and negative sector width for time periods (semesters) for which the Earth was in northern and southern heliolatitudes shows that the predominant polarity for every semester follows, up to a certain extent, the Rosenberg-Coleman effect. However, the statistical support is not satisfactory. The same conclusion was pointed out by a similar study of data grouped over various phases of the solar cycle. Additionally the relative frequency of positive (negative) IMF polarity days, appeared over a mean solar rotation, shows that the general pattern of the mean IMF has a tendency to reoccur in the homologous (corresponding) phases of different solar cycles. © 1982 D. Reidel Publishing Company

Asymmetric variations of the coronal green line intensity

The analysis of the daily measurements of the coronal green line intensity, which have been extensively tested for homogeneity and freedom of trends observed at the Pic-du-Midi observatory during the period 1944-1974, has revealed some characteristic asymmetric variations. A north-south asymmetry of the green line intensity is the main feature of the period 1949-1971 while a south-north one is obvious within 1972-1974 and the minor statistical significance span 1944-1948. On the other hand a significant W-E asymmetry has been confirmed in the whole period 1944-1974. It is noteworthy that the period 1949-1971, where the N-S asymmetry takes place consists a 22-yr solar cycle which starts from the epoch of the solar magnetic field inversion of the solar cycle No. 18 and terminates in the relevant epoch of the cycle No. 20. The combination of N-S and S-N asymmetry with a W-E one makes the NW solar-quarter to appear as the most active of all in the 22-yr cycle 1949-1971, while in the periods 1944-1948 and 1972-1974 the SW quarter is the most active. Finally, from the polar distribution of the green line intensity has been derived that the maximum values of the asymmetries occur in heliocentric sectors ± 10°-20° far from the solar equator on both sides of the central meridian. Physical mechanisms which could contribute to the creation of both N-S and E-W asymmetries of the solar activity and the green line intensity as an accompanied event, like different starting time of an 11-yr solar cycle in the two solar hemispheres, the motion of the Sun towards the Apex, and short-lived 'active' solar longitudes formed by temporal clustering of solar active centers, have been discussed. © 1988 Kluwer Academic Publishers

Asymmetric variations of the coronal green line intensity

The analysis of the daily measurements of the coronal green line intensity, which have been extensively tested for homogeneity and freedom of trends observed at the Pic-du-Midi observatory during the period 1944-1974, has revealed some characteristic asymmetric variations. A north-south asymmetry of the green line intensity is the main feature of the period 1949-1971 while a south-north one is obvious within 1972-1974 and the minor statistical significance span 1944-1948. On the other hand a significant W-E asymmetry has been confirmed in the whole period 1944-1974. It is noteworthy that the period 1949-1971, where the N-S asymmetry takes place consists a 22-yr solar cycle which starts from the epoch of the solar magnetic field inversion of the solar cycle No. 18 and terminates in the relevant epoch of the cycle No. 20. The combination of N-S and S-N asymmetry with a W-E one makes the NW solar-quarter to appear as the most active of all in the 22-yr cycle 1949-1971, while in the periods 1944-1948 and 1972-1974 the SW quarter is the most active. Finally, from the polar distribution of the green line intensity has been derived that the maximum values of the asymmetries occur in heliocentric sectors ± 10°-20° far from the solar equator on both sides of the central meridian. Physical mechanisms which could contribute to the creation of both N-S and E-W asymmetries of the solar activity and the green line intensity as an accompanied event, like different starting time of an 11-yr solar cycle in the two solar hemispheres, the motion of the Sun towards the Apex, and short-lived 'active' solar longitudes formed by temporal clustering of solar active centers, have been discussed. © 1988 Kluwer Academic Publishers