Changes in Solar Rotation over Two Solar Cycles

Solar rotation

This paper reviews current understanding of the internal rotation of the Sun. We summarise the outcome of the latest helioseismic measurements of the angular velocity profile, and review existing dynamical models of rotation in the convection zone and in the radiative zone beneath. Finally, we discuss preliminary results along a new line of investigation.

Solar cycle changes in coronal holes and space weather cycles

[1] Potential field source surface models of the coronal magnetic field, based on Mt. Wilson Observatory synoptic magnetograms, are used to infer the coronal hole sources of low-heliolatitude solar wind over approximately the last three solar cycles. Related key parameters like interplanetary magnetic field and bulk velocity are also calculated. The results illustrate how the evolving contribut...

Solar Flare Cycles

We present a review of different solar flare periodicity intervals. Our analysis includes a statistical investigation of flare occurrence and N-S hemispheric distribution over the last three 11-yr solar cycles (SCs 21-23, corresponding to the period 1976-2001). Moreover, we try to estimate if there is any connection between the flare activity and the strength of solar cycles. For that purpose, ...

Solar Variability and Climate Cycles

Nonlinear analysis of solar cycles

In this paper, the recent improvement of the Wolf sunspot time–series by Hoyt and co-workers has been analysed with the Global Flow Reconstruction (GFR) method (Serre et al. 1996a and b). A nonlinear 4–dimensional chaotic model has been extracted from the data which captures the principal characteristic features of the sunspot group time–series. The hypothesis of interactions between magnetic m...