Transient Phenomena in Multi-thread Arcades of Coronal Loops

The post-flare coronal loops having well defined filamentary structure, often appear as an arcades of thin magnetic threads resembling winding in a curved solenoid or a funnel. Compared to flare timescales, post-flare arcades are long living, well organized structures. Elemental filaments in arcades are, however, in highly dynamic state, showing oscillations, and harboring frequent microflares. These microflares often appear simultaneously in different places. Besides, many individual filaments produce homologous, repetitive microflares. Microflares are often accompanied by short living jets. We present the observations of these events using the data taken with SOT and XRT instruments on Hinode combined with the TRACE 195 ~Å coronal line. The object of the observation is AR 10930 which exhibited several flare events in December, 2006. After a major flare on 13 December, a typical "solenoidal" system of coronal threads was formed that lasted over 6 hours. The observed spatial and temporal regularities in appearence of the EUV transients can be well understood on basis of a spatio-temporal echoes resulted from nonlinear response of a system ("coupled oscillators") to impulsive disturbences associated with the changes in the photospheric magnetic fields. Observations in the SOT chromospheric lines show appearence of precursors of coronal jets and microflares.