Structure of magnetic elds in NOAA active regions 0486 and

Spectacular burst of solar activity in October – November 2003, when large solar spots and intense solar flares dominated the solar surface for many consecutive days, caused intense ge-omagnetic storms. In this paper we analyze solar and interplanetary magnetic fields associ-ated with the storms in October – November 2003. We used space and ground based data in order to compare the orientations of the magnetic fields on the solar surface and at 1AU as well as to estimate parameters of geomagnetic storms during this violent period of geomag-netic activity. Our study further supports earlier reports on the correlation between the CME speed and the strength of the magnetic field in an interplanetary ejecta. A good correspon-dence was also found between directions of the helical magnetic fields in interplanetary ejecta and in the source active regions. These findings are quite significant in terms of their poten-tial to predict the severity of geomagnetic activity 1 – 2 days in advance, immediately after an earth-directed solar eruption. 1