The evolution of pores and the development of penumbrae

We investigate the evolution of the magnetic field in an emerging active re gion near disk center using data from the Advanced Stokes Polarimeter. Spec ifically, we follow the formation of a pore from a radiatively undisturbed region and the formation of a protospot, i.e., the appearance of a rudiment ary penumbral sector for a mature pore. Our approach is to use the temporal evolution of bivariate distribution functions correlating continuum intens ity, I-c, magnetic held magnitude, \B\, magnetic fill fraction, f, local in clination, gamma, local azimuth, phi, and line-of-sight Doppler velocity, u psilon(D). The highlights of our results include, (1) in the pore-forming r egion, a preference for the relatively strong vertical field points (1000-1 500 G) to be redshifted (downflowing) and the appearance of dark pore point s to be at the expense of radiatively undisturbed points; (2) an onset flux of approximate to 2 x 10(19) Mx in a dark pore that appears in an area in which the flux increases by approximate to 1 x 10(20) Mx prior to the pore' s appearance and that previously contained an azimuth center, i.e., a magne tic concentration that otherwise has no continuum-intensity signature; (3) a threshold of (1-1.5) x 10(20) Mx above which a partial penumbra forms; (4 ) the appearance of penumbral elements that at once having the appropriate penumbral range of field strengths, intensities, and inclination angles, i. e., no obvious gradual, increase in the magnetic fields' inclination with i ncreasing flux during the formation of penumbrae; (5) no delay between the appearance of inclined penumbral magnetic fields and the Evershed flow; and (6) a self-similarity between the pore, protospot, and a small mature suns pot with respect to the (\B\, I-c), (\B\, gamma), (f, gamma), and the (upsi lon(D), I-c), (upsilon(D), gamma) distributions.