DYNAMICS OF SOLAR MAGNETIC ARCHES IN THE PHOTOSPHERE AND THE CHROMOSPHERE

Mass motions in chromospheric arch filaments have been observed with i maging spectroscopy (MSDP) at the VTT telescope of the Teide Observato ry. Coordinated observations of time sequences of continuum images wer e carried out at the SVST telescope of the Observatorio del Rogue de l os Muchachos, which provided transverse velocities of photospheric tra cers, by ''local correlation tracking.'' Her profiles along 3 arch fil aments are analysed in terms of ''differential cloud model'', to discu ss the Doppler velocities of chromospheric material. Models of ascendi ng arches with downflows in both legs are investigated. The gas pressu re is neglected, but the free-fall equations are integrated versus tim e (non-stationary case). We first assume circular lines of force with constant radius. We can account for chromospheric velocities, but we c annot fit the slow motion of footpoints derived from photospheric trac ers. A better agreement is obtained by assuming lines of force with fi xed footpoints and variable radius. Typical values are: half distance between footpoints of 10 to 15 Mm, upward velocity at the top of loops of 4 km s(-1) after an integration time of 800 s. The obtained values are consistent with the sizes and the lifetime of arch filaments.