VECTOR MAGNETIC-FIELDS OF EMERGING SOLAR FLUX I - PROPERTIES AT THE SITE OF EMERGENCE

Several small emerging bipolar regions have been observed with the Adv anced Stokes Polarimeter (ASP), including extensive time series measur ements of one small region. Both new and previously recognized propert ies of the actual site of first emergence, where the magnetic field is nearly horizontal to the surface, are revealed by these observations. They provide the most complete and accurate observational description to date of newly emerging vector magnetic fields. We find that: 1) th e strength of the magnetic field at the site of the emergence (where t he vector field is nearly parallel to the solar surface) ranges from a bout 200 to 600 G, 2) as individual flux elements migrate rapidly away from the emergence zone, they attain kilo-Gauss strengths only after becoming oriented nearly vertically, 3) the emergence zone is dotted b y small, transient, upward rising (similar to 1 km s(-1)) horizontal m agnetic elements as indicated by the Doppler shift of the polarized sp ectral profiles, 4) the leading polarity flux coalesces immediately in to a compact region which forms a pore, but the emerging following pol arity flux is spatially much less compact, 5) some ''moving magnetic f eatures'' having the same magnetic polarity as the growing pore, but o n the opposite side of the pore from the emergence zone, coalesce with the pore during the observation period, and 6) the observations sugge st a low canopy of weak horizontal magnetic fields arches over the eme rgence zone. These observations support a widely accepted picture of e merging bipolar flux: the buoy-antly rising flux transports mass from the photosphere into the chromosphere, where it then may drain downwar d along arched magnetic loops. The observed formation of a pore sugges ts that emergence of subsurface structure, not organized flows near th e surface, is largely responsible for the apparent coalescence of suns pots from more diffuse fields viewed at the solar surface. These obser vations neither confirm nor refute the operation of convective collaps e of flux tubes.