Speaker
Description
The tilts of bipolar magnetic regions are believed to be caused by the action
of Coriolis force on rising magnetic flux tubes. Here we analysed the combined
Greenwich and Debrecen observatories sunspot-group data during the period
1874-2017 and the tilt angles of sunspot groups measured at Mt. Wilson
Observatory during the period 1917-1986 and Debrecen Observatory
during the period 1994-2013. We find that there exists about 8-solar
cycle (Gleissberg cycle) trend in the long-term variation of the slope
of Joy's law (increase of tilt angle with latitude). There exists a
reasonably significant correlation between the slope/coefficient of Joy's law
and the slope (coefficient of the
poleward/equatorward angular momentum transport) of the linear relationship
between the rotation residuals and meridional motions of sunspot groups
in the separate hemispheres during Solar
Cycles 16-21. We also find that there exists a good correlation between
north-south difference (asymmetry) in the coefficient of Joy's law and
that in the coefficient of angular momentum transport. These results suggest
that there exists a relationship between the surface/subsurface
poleward/equatorward angular momentum transport and the Joy's law. There is a
suggestion of the strength of the Joy's law depends on the strength of the
poleward angular momentum transport.
| Contribution Type | Poster |
|---|---|
| Theme | Solar Magnetism over Long-Time Scales |
