Speaker
András Ludmány
(MTA Debrecen Heliophysical Observatory)
Description
A refined form of the well known Joy's law has been
formulated by using the new Debrecen tilt angle data. It has
been found that the latitudinal distribution of the tilt
angles is not merely a monotonously increasing function, but
it has a plateau between the latitudes of about 15-25
degrees, where the toroidal field is the strongest. This may
imply an impact of the azimuthal magnetic field on the
Coriolis force acting on the emerging flux ropes. The new
tilt angle databases are derived from two Debrecen sunspot
databases, the DPD (Debrecen Photoheliographic Data, 1974 -
) and SDD (SOHO/MDI-Debrecen Data, 1996-2010) along with
online tools developed for data selection. The new data have
been compared with the traditional sunspot group tilt angle
data bases of Mount Wilson Observatory (1917-85) and
Kodaikanal Solar Observatory (1906-87) and the deviations
have been analysed. Various filters are tested to improve
the reliability of the data to establish a combined dataset.
This work has received funding from the European Community's
Seventh Framework Programme (FP7/2012-2015) under grant
agreement No. 284461 (eHEROES).
Primary author
András Ludmány
(MTA Debrecen Heliophysical Observatory)
