Apparent flows above an active region observed with the Transition Region and Coronal Explorer

The Transition Region and Coronal Explorer (TRACE) observed Active Region 8395 on 1998 December 1 from 1:30:00 to 3:00:00 UT at high cadence in the Fe IX/Fe x channel (log T-e approximate to 6.0). Throughout the observing time, brightness Variations along a dense bundle of coronal field lines in the southwest corner of the active region were observed. Movies made of this region give the impression of continuous intermittent outflow in this bundle of coronal loops; such apparent outflow is often seen in the TRACE data. In this Letter, we present an analysis of four separate flow events occurring in three different loops. These events are used as tracers of the how in order to characterize its physical properties, such as apparent velocity. The projected velocities of the intensity fronts of these flows land hence lower limits of true velocities) are between 5 and 20 Inn s(-1). Comparisons of the observed intensities with those predicted by a quasi-static model suggest that the events can be explained only by a mass flow from the chromosphere into the corona. The persistence of the hows, and their ubiquity in the TRACE observations, indicates that hydrostatic loops models are not applicable to this class of coronal structures.