Outflow Velocity Structure in the Upper Transition Region and Corona

Abstract

Outflow velocity maps in the quiet Sun and coronal hole regions have been observed with the EUV Imaging Spectrometer on Hinode over a range of coronal and transition region temperatures, in order to correlate the solar wind with effects due to the underlying supergranule network and to coronal holes. The cell structure has been identified using data from the Solar Dynamics Observatory: specifically, 1600 A images from the Advanced Imaging Assembly instrument and dopplergrams from the Helioseismic and Magnetic Imager. We find that the expansion of the velocity field with height through the upper transition region and the corona follows the same general pattern that has been long established for the emitted intensities. The outflow velocity field expands laterally with height with the magnetic funnels, eventually filling the space between the cell boundaries. Moreover, the detailed structure of the outflow morphology, combined with the decrease of velocity dispersion with increasing temperature, supports the concept of local stochastic energy release at lower heights. This is consistent with a reconnection process between emerging fields within the cell and the funnels at the cell boundaries.