The vertical structure of arch filament systems in solar emerging flux regions

We study the vertical velocity of arch  filaments in emerging flux regions by measuring their proper motion near the limb in Hα filtergrams and their radial velocity near the disk center in   Hα spectrograms. Both show that arch filaments rise at a velocity between 10 and 15 kms^-1. We discuss the possible mechanisms producting this high velocity. None of them is satisfactory, but it appears that the unloading of the arches by outflow must play a role. From the strength of  Hαemission and D3 absorption, we also  estimate the temperature of arch filaments at 6000 - 15,000 K and the density at 10^11-12cm^-3.