Abstract:
Solar filaments show the position of large-scale polarity-inversion lines and are
used for the reconstruction of large-scale solar magnetic field structure on the basis of Hα
synoptic charts for the periods that magnetographic measurements are not available. Sometimes
crossing filaments are seen in Hα filtergrams. We analyze daily Hα filtergrams from
the archive of Big Bear Solar Observatory for the period of 1999 – 2003 to find crossing
and interacting filaments. A number of examples are presented and filament patterns are
compared with photospheric magnetic field distributions. We have found that all crossing
filaments reveal quadrupolar magnetic configurations of the photospheric field and presume
the presence of null points in the corona.