PROBING THE SUBSURFACE STRUCTURE OF ACTIVE REGIONS WITH THE PHASE INFORMATION IN ACOUSTIC IMAGING

We present the phase information of solar p-mode waves constructed wit h an acoustic imaging technique in the solar interior. There exists a phase shift between the rime series constructed with ingoing waves and outgoing waves. We find that this phase shift is different in an acti ve region and the quiet Sun. The p-mode travel time is shorter in the magnetic regions than in the quiet Sun. We construct a three-dimension al phase shift map of the solar interior. As with the acoustic absorpt ion images, the phase shift features of the active region in maps at t he surface correlate with magnetic fields. The vertical extension of p hase shift features in the active region is smaller in the phase maps constructed with shorter wavelengths. This indicates the vertical spat ial resolution of these three-dimensional phase maps is sensitive to t he range of modes used in constructing the signal. The actual depths o f the phase shift features in the active region may be smaller than th ose shown in the thee-dimensional phase maps.