ACTIVE-REGION MAGNETIC-FIELDS .1. PLAGE FIELDS

We present observations taken with the Advanced Stokes Polarimeter (AS P) in active-region plages and study the frequency distribution of the magnetic held strength (B), inclination with respect to vertical (gam ma), azimuthal orientation (chi), and filling factor (f). The most com mon values at disk center are B = 1400 G, gamma < 10 degrees, no prefe rred east-west orientation, and f = 15%. At disk center, there is a co mponent of weak (< 1000 G), more horizontal fields that corresponds to arching field lines connecting footpoints of different polarities. Th e center-to-limb variation (CLV) of the field strength shows that, clo se to the limb (mu = 0.3), the held strength is reduced to 800 G from its disk-center value. This can be interpreted as a gradient of B with height in solar plages of around -3 G km(-1). From this CLV study, we also deduce that magnetic held lines remain vertical for the entire r ange of heights involved. A similar analysis is performed for structur es found in active regions that show a continuous distribution of azim uths (resembling sunspots) but that do not have a darkening in continu um. These ''azimuth centers'' show slightly larger values of B than no rmal plages, in particular at their magnetic center. Filling factors a re also larger on average for these structures. The velocities in the magnetic component of active regions have been studied for both averag ed Stokes profiles over the entire active region and for the spatially resolved data. The averaged profiles (more representative of high fil ling factor regions) do not show any significant mean velocities. Howe ver, the spatial average of Doppler velocities derived from the spatia lly resolved profiles (i.e., unweighted by filling factor) show a net redshift at disk center of 200 m s(-1). The spatially resolved velocit ies show a strong dependence on filling factor. Both mean velocities a nd standard deviations are reduced when the filling factor increases. This is interpreted as a reduction of the p-mode amplitude within the magnetic component. Strong evidence for velocities transverse to the m agnetic field lines has been found. Typical rms values are between 200 and 300 m s(-1), depending on the filling factor. The possible import ance of these transverse motions for the dynamics of the upper atmosph eric layers is discussed. The asymmetries of the Stokes profiles and t heir CLV have been studied. The averaged Stokes V profiles show amplit ude and area asymmetries that are positive at disk center and become n egative at the Limb. Both asymmetries, and for the two Fe I Lines, are maximized away from disk center. The spatially resolved amplitude asy mmetries show a clear dependence on filling factor: the larger the fil ling factor, the smaller the amplitude asymmetry. On the other hand, t he area asymmetry is almost independent of the filling factor. The onl y observed dependence is the existence of negative area-asymmetry prof iles at disk center for filling factors smaller than 0.2. Around 20% o f the observed points in a given plage have negative area asymmetry. T he amplitude asymmetry of Stokes V is, on the other hand, always posit ive. The amplitude asymmetries of the linear polarization profiles are observed to have the same sign as the Stokes V profiles. Similarly, t he same CLV variation of the linear polarization amplitude asymmetries as for Stokes V has been found. The scenarios in which this similarit y can exist are studied in some detail.